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2. Photo-nuclear cross sections on $^{197}$Au, an update on the gold standard

Author

Song, J., Rotsch, D., Nolen, J. A., Gampa, R., de Kruijff, R. M., Brossard, T., Howell, C. R., Krishichayan, F., Wu, Y. K., Mikhailov, S., Ahmed, M. W., and Janssens, R. V. F.

Subjects
Nuclear Experiment
Abstract

A method was developed for measuring photonuclear reactions concurrently at several discrete photon beam energies on a stack of different target materials via a single irradiation. Concentric ring targets of the materials (in order from front to back targets: Au, TiO$_2$, Zn, Os, and Au) were irradiated at the High Intensity Gamma-ray Source (HI$\gamma$S). As a proof of principle, we report the result of the cross section measurements from the front Au target. The excitation functions of the $^{197}$Au($\gamma$,n)$^{196}$Au and $^{197}$Au($\gamma$,3n)$^{194}$Au reactions were determined in the incident photon energy range of 13-31 MeV using quasi-monoenergetic photon beams provided at HI$\gamma$S. The cross sections of the combined ground state (2$^{-}$) and short-lived first isomeric state (m1, 5$^{+}$), and of the second isomeric state (m2, 12$^{-}$) in the $^{196}$Au production are obtained separately by subtracting the $\gamma$ rays from the internal conversion of the second isomeric state. The excitation function of the second isomeric state via the photon-induced reaction $^{197}$Au($\gamma$,n)$^{196m2}$Au was measured for the first time. By using the activation method rather than direct neutron counting, the exclusive cross sections for the ($\gamma$,n) and ($\gamma$,3n) reactions were determined. Comparing the yields from the front and back gold targets validates our ability to simulate the effect of photon scattering in the target stack and provides a method for assessing the systematic uncertainty of our technique.

Published
2024

3. Fundamental Symmetries, Neutrons, and Neutrinos (FSNN): Whitepaper for the 2023 NSAC Long Range Plan

Author

Acharya, B., Adams, C., Aleksandrova, A. A., Alfonso, K., An, P., Baeßler, S., Balantekin, A. B., Barbeau, P. S., Bellini, F., Bellini, V., Beminiwattha, R. S., Bernauer, J. C., Bhattacharya, T., Bishof, M., Bolotnikov, A. E., Breur, P. A., Brodeur, M., Brodsky, J. P., Broussard, L. J., Brunner, T., Burdette, D. P., Caylor, J., Chiu, M., Cirigliano, V., Clark, J. A., Clayton, S. M., Daniels, T. V., Darroch, L., Davoudi, Z., de Gouvêa, A., Dekens, W., Demarteau, M., DeMille, D., Deshpande, A., Detwiler, J. A., Dodson, G. W., Dolinski, M. J., Elliott, S. R., Engel, J., Erler, J., Filippone, B. W., Fomin, N., Formaggio, J. A., Friesen, F. Q. L., Fry, J., Fujikawa, B. K., Fuller, G., Fuyuto, K., Gallant, A. T., Gallina, G., Ruiz, A. Garcia, Ruiz, R. F. Garcia, Gardner, S., Gonzalez, F. M., Gratta, G., Gruszko, J., Gudkov, V., Guiseppe, V. E., Gutierrez, T. D., Hansen, E. V., Hardy, C. A., Haxton, W. C., Hayen, L., Hedges, S., Heeger, K. M., Heffner, M., Heise, J., Henning, R., Hergert, H., Hertzog, D. W., Aguilar, D. Hervas, Holt, J. D., Hoogerheide, S. F., Hoppe, E. W., Horoi, M., Howell, C. R., Huang, M., Hutzler, N. R., Imam, K., Ito, T. M., Jamil, A., Janssens, R. V., Jayich, A. M., Jones, B. J. P., Kammel, P., Liu, K. F., Khachatryan, V., King, P. M., Klein, J. R., Kneller, J. P., Kolomensky, Yu. G., Korsch, W., Krücken, R., Kumar, K. S., Launey, K. D., Lawrence, D., Leach, K. G., Lehnert, B., Lenardo, B. G., Li, Z., Lin, H. -W., Longfellow, B., Lopez-Caceres, S., Lunardini, C., MacLellan, R., Markoff, D. M., Maruyama, R. H., Mathews, D. G., Melconian, D., Mereghetti, E., Mohanmurthy, P., Moore, D. C., Mueller, P. E., Mumm, H. P., Nazarewicz, W., Newby, J., Nicholson, A. N., Novitski, E., Ondze, J. C. Nzobadila, O'Donnell, T., Gann, G. D. Orebi, Orrell, J. L., Ouellet, J. L., Parno, D. S., Paschke, K. D., Pastore, S., Pattie Jr, R. W., Petrov, A. A., Pitt, M. L., Plaster, B., Pocanic, D., Pocar, A., Poon, A. W. P., Radford, D. C., Rahangdale, H., Rasco, B. C., Rasiwala, H., Redwine, R. P., Ritz, A., Rogers, L., Ron, G., Saldanha, R., Sangiorgio, S., Sargsyan, G. H., Saunders, A., Savard, G., Schaper, D. C., Scholberg, K., Scielzo, N. D., Seng, C. -Y., Shindler, A., Singh, J. T., Singh, M., Singh, V., Snow, W. M., Soma, A. K., Souder, P. A., Speller, D. H., Stachurska, J., Surukuchi, P. T., Oregui, B. Tapia, Tomalak, O., Torres, J. A., Tyuka, O. A., VanDevender, B. A., Varriano, L., Vogt, R., Walker-Loud, A., Wamba, K., Watkins, S. L., Wietfeldt, F. E., Williams, W. D., Wilson, J. T., Winslow, L., Yan, X. L., Yang, L., Young, A. R., Zheng, X., and Zhou, Y.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

This whitepaper presents the research priorities decided on by attendees of the 2022 Town Meeting for Fundamental Symmetries, Neutrons and Neutrinos, which took place December 13-15, 2022 in Chapel Hill, NC, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long Range Planning process. A total of 275 scientists registered for the meeting. The whitepaper makes a number of explicit recommendations and justifies them in detail.

Published
2023

4. The Present and Future of QCD

Author

Achenbach, P., Adhikari, D., Afanasev, A., Afzal, F., Aidala, C. A., Al-bataineh, A., Almaalol, D. K., Amaryan, M., Androić, D., Armstrong, W. R., Arratia, M., Arrington, J., Asaturyan, A., Aschenauer, E. C., Atac, H., Avakian, H., Averett, T., Gayoso, C. Ayerbe, Bai, X., Barish, K. N., Barnea, N., Basar, G., Battaglieri, M., Baty, A. A., Bautista, I., Bazilevsky, A., Beattie, C., Behera, S. C., Bellini, V., Bellwied, R., Benesch, J. F., Benmokhtar, F., Bernardes, C. A., Bernauer, J. C., Bhatt, H., Bhatta, S., Boer, M., Boettcher, T. J., Bogacz, S. A., Bossi, H. J., Brandenburg, J. D., Brash, E. J., Briceño, R. A., Briscoe, W. J., Brodsky, S. J., Brown, D. A., Burkert, V. D., Caines, H., Cali, I. A., Camsonne, A., Carman, D. S., Caylor, J., Cerci, S., Llatas, M. Chamizo, Chatterjee, S., Chen, J. P., Chen, Y., Chen, Y. -C., Chien, Y. -T., Chou, P. -C., Chu, X., Chudakov, E., Cline, E., Cloët, I. C., Cole, P. L., Connors, M. E., Constantinou, M., Cosyn, W., Dusa, S. Covrig, Cruz-Torres, R., D'Alesio, U., da Silva, C., Davoudi, Z., Dean, C. T., Dean, D. J., Demarteau, M., Deshpande, A., Detmold, W., Deur, A., Devkota, B. R., Dhital, S., Diefenthaler, M., Dobbs, S., Döring, M., Dong, X., Dotel, R., Dow, K. A., Downie, E. J., Drachenberg, J. L., Dumitru, A., Dunlop, J. C., Dupre, R., Durham, J. M., Dutta, D., Edwards, R. G., Ehlers, R. J., Fassi, L. El, Elaasar, M., Elouadrhiri, L., Engelhardt, M., Ent, R., Esumi, S., Evdokimov, O., Eyser, O., Fanelli, C., Fatemi, R., Fernando, I. P., Flor, F. A., Fomin, N., Frawley, A. D., Frederico, T., Fries, R. J., Gal, C., Gamage, B. R., Gamberg, L., Gao, H., Gaskell, D., Geurts, F., Ghandilyan, Y., Ghimire, N., Gilman, R., Gleason, C., Gnanvo, K., Gothe, R. W., Greene, S. V., Grießhammer, H. W., Grossberndt, S. K., Grube, B., Hackett, D. C., Hague, T. J., Hakobyan, H., Hansen, J. -O., Hatta, Y., Hattawy, M., Havener, L. B., Hen, O., Henry, W., Higinbotham, D. W., Hobbs, T. J., Hodges, A. M., Holmstrom, T., Hong, B., Horn, T., Howell, C. R., Huang, H. Z., Huang, M., Huang, S., Huber, G. M., Hyde, C. E., Isupov, E. L., Jacobs, P. M., Jalilian-Marian, J., Jentsch, A., Jheng, H., Ji, C. -R., Ji, X., Jia, J., Jones, D. C., Jones, M. K., Kalantarians, N., Kalicy, G., Kang, Z. B., Karthein, J. M., Keller, D., Keppel, C., Khachatryan, V., Kharzeev, D. E., Kim, H., Kim, M., Kim, Y., King, P. M., Kinney, E., Klein, S. R., Ko, H. S., Koch, V., Kohl, M., Kovchegov, Y. V., Krintiras, G. K., Kubarovsky, V., Kuhn, S. E., Kumar, K. S., Kutz, T., Lajoie, J. G., Lauret, J., Lavrukhin, I., Lawrence, D., Lee, J. H., Lee, K., Lee, S., Lee, Y. -J., Li, S., Li, W., Li, Xiaqing, Li, Xuan, Liao, J., Lin, H. -W., Lisa, M. A., Liu, K. -F., Liu, M. X., Liu, T., Liuti, S., Liyanage, N., Llope, W. J., Loizides, C., Longo, R., Lorenzon, W., Lunkenheimer, S., Luo, X., Ma, R., McKinnon, B., Meekins, D. G., Mehtar-Tani, Y., Melnitchouk, W., Metz, A., Meyer, C. A., Meziani, Z. -E., Michaels, R., Michel, J. K. L., Milner, R. G., Mkrtchyan, H., Mohanmurthy, P., Mohanty, B., Mokeev, V. I., Moon, D. H., Mooney, I. A., Morningstar, C., Morrison, D. P., Müller, B., Mukherjee, S., Mulligan, J., Camacho, C. Munoz, Quijada, J. A. Murillo, Murray, M. J., Nadeeshani, S. A., Nadel-Turonski, P., Nam, J. D., Nattrass, C. E., Nijs, G., Noronha, J., Noronha-Hostler, J., Novitzky, N., Nycz, M., Olness, F. I., Osborn, J. D., Pak, R., Pandey, B., Paolone, M., Papandreou, Z., Paquet, J. -F., Park, S., Paschke, K. D., Pasquini, B., Pasyuk, E., Patel, T., Patton, A., Paudel, C., Peng, C., Peng, J. C., Da Costa, H. Pereira, Perepelitsa, D. V., Peters, M. J., Petreczky, P., Pisarski, R. D., Pitonyak, D., Ploskon, M. A., Posik, M., Poudel, J., Pradhan, R., Prokudin, A., Pruneau, C. A., Puckett, A. J. R., Pujahari, P., Putschke, J., Pybus, J. R., Qiu, J. -W., Rajagopal, K., Ratti, C., Read, K. F., Reed, R., Richards, D. G., Riedl, C., Ringer, F., Rinn, T., West, J. Rittenhouse, Roche, J., Rodas, A., Roland, G., Romero-López, F., Rossi, P., Rostomyan, T., Ruan, L., Ruimi, O. M., Saha, N. R., Sahoo, N. R., Sakaguchi, T., Salazar, F., Salgado, C. W., Salmè, G., Salur, S., Santiesteban, S. N., Sargsian, M. M., Sarsour, M., Sato, N., Satogata, T., Sawada, S., Schäfer, T., Scheihing-Hitschfeld, B., Schenke, B., Schindler, S. T., Schmidt, A., Seidl, R., Shabestari, M. H., Shanahan, P. E., Shen, C., Sheng, T. -A., Shepherd, M. R., Sickles, A. M., Sievert, M. D., Smith, K. L., Song, Y., Sorensen, A., Souder, P. A., Sparveris, N., Srednyak, S., Leiton, A. G. Stahl, Stasto, A. M., Steinberg, P., Stepanyan, S., Stephanov, M., Stevens, J. R., Stewart, D. J., Stewart, I. W., Stojanovic, M., Strakovsky, I., Strauch, S., Strickland, M., Cerci, D. Sunar, Suresh, M., Surrow, B., Syritsyn, S., Szczepaniak, A. P., Tadepalli, A. S., Tang, A. H., Takaki, J. D. Tapia, Tarnowsky, T. J., Tawfik, A. N., Taylor, M. I., Tennant, C., Thiel, A., Thomas, D., Tian, Y., Timmins, A. R., Tribedy, P., Tu, Z., Tuo, S., Ullrich, T., Umaka, E., Upton, D. W., Vary, J. P., Velkovska, J., Venugopalan, R., Vijayakumar, A., Vitev, I., Vogelsang, W., Vogt, R., Vossen, A., Voutier, E., Vovchenko, V., Walker-Loud, A., Wang, F., Wang, J., Wang, X., Wang, X. -N., Weinstein, L. B., Wenaus, T. J., Weyhmiller, S., Wissink, S. W., Wojtsekhowski, B., Wong, C. P., Wood, M. H., Wunderlich, Y., Wyslouch, B., Xiao, B. W., Xie, W., Xiong, W., Xu, N., Xu, Q. H., Xu, Z., Yaari, D., Yao, X., Ye, Z., Ye, Z. H., Yero, C., Yuan, F., Zajc, W. A., Zhang, C., Zhang, J., Zhao, F., Zhao, Y., Zhao, Z. W., Zheng, X., Zhou, J., and Zurek, M.

Subjects
High Energy Physics - Phenomenology, High Energy Physics - Experiment, Nuclear Experiment, Nuclear Theory
Abstract

This White Paper presents the community inputs and scientific conclusions from the Hot and Cold QCD Town Meeting that took place September 23-25, 2022 at MIT, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long Range Planning process. A total of 424 physicists registered for the meeting. The meeting highlighted progress in Quantum Chromodynamics (QCD) nuclear physics since the 2015 LRP (LRP15) and identified key questions and plausible paths to obtaining answers to those questions, defining priorities for our research over the coming decade. In defining the priority of outstanding physics opportunities for the future, both prospects for the short (~ 5 years) and longer term (5-10 years and beyond) are identified together with the facilities, personnel and other resources needed to maximize the discovery potential and maintain United States leadership in QCD physics worldwide. This White Paper is organized as follows: In the Executive Summary, we detail the Recommendations and Initiatives that were presented and discussed at the Town Meeting, and their supporting rationales. Section 2 highlights major progress and accomplishments of the past seven years. It is followed, in Section 3, by an overview of the physics opportunities for the immediate future, and in relation with the next QCD frontier: the EIC. Section 4 provides an overview of the physics motivations and goals associated with the EIC. Section 5 is devoted to the workforce development and support of diversity, equity and inclusion. This is followed by a dedicated section on computing in Section 6. Section 7 describes the national need for nuclear data science and the relevance to QCD research., Comment: QCD Town Meeting White Paper, as submitted to 2023 NSAC LRP committee on Feb. 28, 2023

Published
2023
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5. A new direct detection electron scattering experiment to search for the X17 particle

Author

Dutta, D., Gao, H., Gasparian, A., Hague, T. J., Liyanage, N., Paremuzyan, R., Peng, C., Xiong, W., Achenbach, P., Ahmidouch, A., Ali, S., Avakian, H., Ayerbe-Gayoso, C., Bai, X., Battaglieri, M., Bhatt, H., Bianconi, A., Boyd, J., Byer, D., Cole, P. L., Costantini, G., Davis, S., De Napoli, M., De Vita, R., Devkota, B., Dharmasena, B., Dunne, J., Fassi, L. El, Gamage, V., Gan, L., Gnanvo, K., Gosta, G., Higinbotham, D., Howell, C., Jeffas, S., Jian, S., Karki, A., Karki, B., Khachatryan, V., Khandaker, M., Kubarovsky, V., Larin, I., Leali, M., Mascagna, V., Matousek, G., Migliorati, S., Miskimen, R., Mohanmurthy, P., Nguyen, H., Pasyuk, E., Rathnayake, A., West, J. Rittenhouse, Shahinyan, A., Smith, A., Stepanyan, S., van Nieuwenhuizen, E., Venturelli, L., Yu, B., Zhao, Z., and Zhou, J.

Subjects
Nuclear Experiment
Abstract

A new electron scattering experiment (E12-21-003) to verify and understand the nature of hidden sector particles, with particular emphasis on the so-called X17 particle, has been approved at Jefferson Lab. The search for these particles is motivated by new hidden sector models introduced to account for a variety of experimental and observational puzzles: excess in $e^+e^-$ pairs observed in multiple nuclear transitions, the 4.2$\sigma$ disagreement between experiments and the standard model prediction for the muon anomalous magnetic moment, and the small-scale structure puzzle in cosmological simulations. The aforementioned X17 particle has been hypothesized to account for the excess in $e^+e^-$ pairs observed from the $^8$Be M1, $^4$He M0, and, most recently, $^{12}$C E1 nuclear transitions to their ground states observed by the ATOMKI group. This experiment will use a high resolution electromagnetic calorimeter to search for or set new limits on the production rate of the X17 and other hidden sector particles in the $3 - 60$ MeV mass range via their $e^+e^-$ decay (or $\gamma\gamma$ decay with limited tracking). In these models, the $1 - 100$ MeV mass range is particularly well-motivated and the lower part of this range still remains unexplored. Our proposed direct detection experiment will use a magnetic-spectrometer-free setup (the PRad apparatus) to detect all three final state particles in the visible decay of a hidden sector particle for an effective control of the background and will cover the proposed mass range in a single setting. The use of the well-demonstrated PRad setup allows for an essentially ready-to-run and uniquely cost-effective search for hidden sector particles in the $3 - 60$ MeV mass range with a sensitivity of 8.9$\times$10$^{-8}$ - 5.8$\times$10$^{-9}$ to $\epsilon^2$, the square of the kinetic mixing interaction constant between hidden and visible sectors., Comment: 6 pages, 7 figures. arXiv admin note: substantial text overlap with arXiv:2108.13276

Published
2023

6. A new direct detection electron scattering experiment to search for the X17 particle

Author

Dutta, D, Gao, H, Gasparian, A, Hague, TJ, Liyanage, N, Paremuzyan, R, Peng, C, Xiong, W, Achenbach, P, Ahmidouch, A, Ali, S, Avakian, H, Ayerbe-Gayoso, C, Bai, X, Battaglieri, M, Bhatt, H, Bianconi, A, Boyd, J, Byer, D, Cole, PL, Costantini, G, Davis, S, Napoli, M De, Vita, R De, Devkota, B, Dharmasena, B, Dunne, J, Fassi, L El, Gamage, V, Gan, L, Gnanvo, K, Gosta, G, Higinbotham, D, Howell, C, Jeffas, S, Jian, S, Karki, A, Karki, B, Khachatryan, V, Khandaker, M, Kubarovsky, V, Larin, I, Leali, M, Mascagna, V, Matousek, G, Migliorati, S, Miskimen, R, Mohanmurthy, P, Nguyen, H, Pasyuk, E, Rathnayake, A, West, J Rittenhouse, Shahinyan, A, Smith, A, Stepanyan, S, Nieuwenhuizen, E van, Venturelli, L, Yu, B, Zhao, Z, and Zhou, J

Subjects
nucl-ex
Abstract

A new electron scattering experiment (E12-21-003) to verify and understandthe nature of hidden sector particles, with particular emphasis on theso-called X17 particle, has been approved at Jefferson Lab. The search forthese particles is motivated by new hidden sector models introduced to accountfor a variety of experimental and observational puzzles: excess in $e^+e^-$pairs observed in multiple nuclear transitions, the 4.2$\sigma$ disagreementbetween experiments and the standard model prediction for the muon anomalousmagnetic moment, and the small-scale structure puzzle in cosmologicalsimulations. The aforementioned X17 particle has been hypothesized to accountfor the excess in $e^+e^-$ pairs observed from the $^8$Be M1, $^4$He M0, and,most recently, $^{12}$C E1 nuclear transitions to their ground states observedby the ATOMKI group. This experiment will use a high resolution electromagneticcalorimeter to search for or set new limits on the production rate of the X17and other hidden sector particles in the $3 - 60$ MeV mass range via their$e^+e^-$ decay (or $\gamma\gamma$ decay with limited tracking). In thesemodels, the $1 - 100$ MeV mass range is particularly well-motivated and thelower part of this range still remains unexplored. Our proposed directdetection experiment will use a magnetic-spectrometer-free setup (the PRadapparatus) to detect all three final state particles in the visible decay of ahidden sector particle for an effective control of the background and willcover the proposed mass range in a single setting. The use of thewell-demonstrated PRad setup allows for an essentially ready-to-run anduniquely cost-effective search for hidden sector particles in the $3 - 60$ MeVmass range with a sensitivity of 8.9$\times$10$^{-8}$ - 5.8$\times$10$^{-9}$ to$\epsilon^2$, the square of the kinetic mixing interaction constant betweenhidden and visible sectors.

Published
2023

8. Proton Compton Scattering from Linearly Polarized Gamma Rays

Author

Li, X., Ahmed, M. W., Banu, A., Bartram, C., Crowe, B., Downie, E. J., Emamian, M., Feldman, G., Gao, H., Godagama, D., Grießhammer, H. W., Howell, C. R., Karwowski, H. J., Kendellen, D. P., Kovash, M. A., Leung, K. K. H., Markoff, D. M., McGovern, J. A., Mikhailov, S., Pywell, R. E., Sikora, M. H., Silano, J. A., Sosa, R. S., Spraker, M. C., Swift, G., Wallace, P., Weller, H. R., Whisnant, C. S., Wu, Y. K., and Zhao, Z. W.

Subjects
Nuclear Experiment
Abstract

Differential cross sections for Compton scattering from the proton have been measured at scattering angles of $55^\circ$, $90^\circ$, and $125^\circ$ in the laboratory frame using quasimonoenergetic linearly (circularly) polarized photon beams with a weighted mean energy value of 83.4\,MeV (81.3\,MeV). These measurements were performed at the High Intensity Gamma-Ray Source facility at the Triangle Universities Nuclear Laboratory. The results are compared to previous measurements and are interpreted in the chiral effective field theory framework to extract the electromagnetic dipole polarizabilities of the proton, which gives $\alpha_{E1}^p = 13.8\pm1.2_{\rm stat}\pm0.1_{\rm BSR}\pm0.3_{\rm theo}, \beta_{M1}^p = 0.2\mp1.2_{\rm stat}\pm0.1_{\rm BSR}\mp0.3_{\rm theo}$ in units of 10$^{-4}$\, fm$^3$., Comment: 6 pages, 4 figures. Version identical to the published letter

Published
2022
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9. Measurement of the $^1S_0$ neutron-neutron effective range in neutron-deuteron breakup

Author

Malone, R. C., Crowell, A. S., Cumberbatch, L. C., Fallin, B. A., Friesen, F. Q. L., Howell, C. R., Malone, C. R., Ticehurst, D. R., Tornow, W., Markoff, D. M., Crowe, B. J., and Witała, H.

Subjects
Nuclear Experiment
Abstract

We report the most precise determination of the $^{1}S_{0}$ neutron-neutron effective range parameter ($r_{nn}$) from neutron-neutron quasifree scattering in neutron-deuteron breakup. The experiment setup utilized a collimated beam of 15.5 MeV neutrons and an array of eight neutron detectors positioned at angles sensitive to several quasifree scattering kinematic configurations. The two neutrons emitted from the breakup reaction were detected in coincidence and time-of-flight techniques were used to determine their energies. The beam-target luminosity was measured in-situ with the yields from neutron-deuteron elastic scattering. Rigorous Faddeev-type calculations using the CD Bonn nucleon-nucleon potential were fit to our cross-section data to determine the value of $r_{nn}$. The analysis was repeated using a semilocal momentum-space regularized N$^4$LO$^+$ chiral interaction potential. We obtained values of $r_{nn} = 2.86 \pm 0.01 \,(stat) \pm 0.10 \,(sys)$ fm and $r_{nn} = 2.87 \pm 0.01 \,(stat) \pm 0.10 \,(sys)$ fm using the CD Bonn and N$^4$LO$^+$ potentials, respectively. Our results are consistent with charge symmetry and previously reported values of $r_{nn}$., Comment: Ver 1: 6 pages, 3 figures, 3 tables; Submitted to Phys Lett B; Ver 2: 8 pages, 3 figures, 3 tables; Changes: 1. Figure 2 plots neutron energy instead of time-of-flight and shows kinematic locus for clarity. Plot true coincidence spectra instead of raw and accidental coincidence spectra. 2. Figure 3 vertical instead of horizontal. 3. Minor text changes for clarity

Published
2022
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11. A Direct Detection Search for Hidden Sector New Particles in the 3-60 MeV Mass Range

Author

Ahmidouch, A., Davis, S., Gasparian, A., Hague, T. J., Mtingwa, S., Pedroni, R., Ayerbe-Gayoso, C., Bhatt, H., Devkota, B., Dunne, J., Dutta, D., Fassi, L. El, Karki, A., Mohanmurthy, P., Peng, C., Ali, S., Bai, X., Boyd, J., Dharmasena, B., Gamage, V., Gnanvo, K., Jeffas, S., Jian, S., Liyanage, N., Nguyen, H., Rathnayake, A., Khandaker, M., Byer, D., Gao, H., Howell, C., Karki, B., Khachatryan, V., Matousek, G., van Nieuwenhuizen, E., Smith, A., Yu, B., Zhao, Z., Zhou, J., Shahinyan, A., Higinbotham, D., Kubarovsky, V., Paremuzyan, R., Pasyuk, E., Stepanyan, S., Avakian, H., Battaglieri, M., De Vita, R., Bianconi, A., Constantini, G., Gosta, G., Leali, M., Migliorati, S., Venturelli, L., Mascagna, V., De Napoli, M., Larin, I., Miskimen, R., Cole, P., Xiong, W., and West, J. Rittenhouse

Subjects
Nuclear Experiment, Physics - Instrumentation and Detectors
Abstract

In our quest to understand the nature of dark matter and discover its non-gravitational interactions with ordinary matter, we propose an experiment using a \pbo ~calorimeter to search for or set new limits on the production rate of i) hidden sector particles in the $3 - 60$ MeV mass range via their $e^+e^-$ decay (or $\gamma\gamma$ decay with limited tracking), and ii) the hypothetical X17 particle, claimed in multiple recent experiments. The search for these particles is motivated by new hidden sector models and dark matter candidates introduced to account for a variety of experimental and observational puzzles: the small-scale structure puzzle in cosmological simulations, anomalies such as the 4.2$\sigma$ disagreement between experiments and the standard model prediction for the muon anomalous magnetic moment, and the excess of $e^+e^-$ pairs from the $^8$Be M1 and $^4$He nuclear transitions to their ground states observed by the ATOMKI group. In these models, the $1 - 100$ MeV mass range is particularly well-motivated and the lower part of this range still remains unexplored. Our proposed direct detection experiment will use a magnetic-spectrometer-free setup (the PRad apparatus) to detect all three final state particles in the visible decay of a hidden sector particle allowing for an effective control of the background and will cover the proposed mass range in a single setting. The use of the well-demonstrated PRad setup allows for an essentially ready-to-run and uniquely cost-effective search for hidden sector particles in the $3 - 60$ MeV mass range with a sensitivity of 8.9$\times$10$^{-8}$ - 5.8$\times$10$^{-9}$ to $\epsilon^2$, the square of the kinetic mixing interaction constant between hidden and visible sectors. This updated proposal includes our response to the PAC49 comments., Comment: 47 pages, 44 Figures. JLab PAC50 Proposal

Published
2021

13. International Workshop on Next Generation Gamma-Ray Source

Author

Howell, C. R., Ahmed, M. W., Afanasev, A., Alesini, D., Annand, J. R. M., Aprahamian, A., Balabanski, D. L., Benson, S. V., Bernstein, A., Brune, C. R., Byrd, J., Carlsten, B. E., Champagne, A. E., Chattopadhyay, S., Davis, D., Downie, E. J., Durham, M. J., Feldman, G., Gao, H., Geddes, C. G. R., Griesshammer, H. W., Hajima, R., Hao, H., Hornidge, D., Isaak, J., Janssens, R. V. F., Kendellen, D. P., Kovash, M. A., Martel, P. P., Meissner, Ulf-G., Miskimen, R., Pasquini, B., Phillips, D. R., Pietralla, N., Savran, D., Schindler, M. R., Sikora, M. H., Snow, W. M., Springer, R. P., Sun, C., Tang, C., Tiburzi, B., Tonchev, A. P., Tornow, W., Ur, C. A., Wang, D., Weller, H. R., Werner, V., Wu, Y. K., Yan, J., Zhao, Z., Zilges, A., and Zomer, F.

Subjects
Nuclear Experiment, Nuclear Theory, Physics - Accelerator Physics
Abstract

A workshop on The Next Generation Gamma-Ray Sources sponsored by the Office of Nuclear Physics at the Department of Energy, was held November 17--19, 2016 in Bethesda, Maryland. The goals of the workshop were to identify basic and applied research opportunities at the frontiers of nuclear physics that would be made possible by the beam capabilities of an advanced laser Compton beam facility. To anchor the scientific vision to realistically achievable beam specifications using proven technologies, the workshop brought together experts in the fields of electron accelerators, lasers, and optics to examine the technical options for achieving the beam specifications required by the most compelling parts of the proposed research programs. An international assembly of participants included current and prospective $\gamma$-ray beam users, accelerator and light-source physicists, and federal agency program managers. Sessions were organized to foster interactions between the beam users and facility developers, allowing for information sharing and mutual feedback between the two groups. The workshop findings and recommendations are summarized in this whitepaper.

Published
2020

15. A Direct Detection Search for Hidden Sector New Particles in the 3-60 MeV Mass Range

Author

Ahmidouch, A, Davis, S, Gasparian, A, Hague, TJ, Mtingwa, S, Pedroni, R, Ayerbe-Gayoso, C, Bhatt, H, Devkota, B, Dunne, J, Dutta, D, Fassi, L El, Karki, A, Mohanmurthy, P, Peng, C, Ali, S, Bai, X, Boyd, J, Dharmasena, B, Gamage, V, Gnanvo, K, Jeffas, S, Jian, S, Liyanage, N, Nguyen, H, Rathnayake, A, Khandaker, M, Byer, D, Gao, H, Howell, C, Karki, B, Khachatryan, V, Matousek, G, Nieuwenhuizen, E van, Smith, A, Yu, B, Zhao, Z, Zhou, J, Shahinyan, A, Higinbotham, D, Kubarovsky, V, Paremuzyan, R, Pasyuk, E, Stepanyan, S, Avakian, H, Battaglieri, M, Vita, R De, Bianconi, A, Constantini, G, Gosta, G, Leali, M, Migliorati, S, Venturelli, L, Mascagna, V, Napoli, M De, Larin, I, Miskimen, R, Cole, P, Xiong, W, and West, J Rittenhouse

Subjects
nucl-ex, physics.ins-det
Abstract

In our quest to understand the nature of dark matter and discover itsnon-gravitational interactions with ordinary matter, we propose an experimentusing a \pbo ~calorimeter to search for or set new limits on the productionrate of i) hidden sector particles in the $3 - 60$ MeV mass range via their$e^+e^-$ decay (or $\gamma\gamma$ decay with limited tracking), and ii) thehypothetical X17 particle, claimed in multiple recent experiments. The searchfor these particles is motivated by new hidden sector models and dark mattercandidates introduced to account for a variety of experimental andobservational puzzles: the small-scale structure puzzle in cosmologicalsimulations, anomalies such as the 4.2$\sigma$ disagreement between experimentsand the standard model prediction for the muon anomalous magnetic moment, andthe excess of $e^+e^-$ pairs from the $^8$Be M1 and $^4$He nuclear transitionsto their ground states observed by the ATOMKI group. In these models, the $1 -100$ MeV mass range is particularly well-motivated and the lower part of thisrange still remains unexplored. Our proposed direct detection experiment willuse a magnetic-spectrometer-free setup (the PRad apparatus) to detect all threefinal state particles in the visible decay of a hidden sector particle allowingfor an effective control of the background and will cover the proposed massrange in a single setting. The use of the well-demonstrated PRad setup allowsfor an essentially ready-to-run and uniquely cost-effective search for hiddensector particles in the $3 - 60$ MeV mass range with a sensitivity of8.9$\times$10$^{-8}$ - 5.8$\times$10$^{-9}$ to $\epsilon^2$, the square of thekinetic mixing interaction constant between hidden and visible sectors. Thisupdated proposal includes our response to the PAC49 comments.

Published
2021

16. Neutron-neutron quasifree scattering in neutron-deuteron breakup at 10 MeV

Author

Malone, R. C., Crowell, A. S., Cumberbatch, L. C., Fallin, B. A., Friesen, F. Q. L., Howell, C. R., Malone, C. R., Ticehurst, D. R., Tornow, W., Markoff, D. M., Crowe, B. J., and Witała, H.

Subjects
Nuclear Experiment
Abstract

New measurements of the neutron-neutron quasifree scattering cross section in neutron-deuteron breakup at an incident neutron energy of 10.0 MeV are reported. The experiment setup was optimized to evaluate the technique for determining the integrated beam-target luminosity in neutron-neutron coincidence cross-section measurements in neutron-deuteron breakup. The measurements were carried out with a systematic uncertainty of $\pm 5.6 \%$. Our data are in agreement with theoretical calculations performed using the CD-Bonn nucleon-nucleon potential in the Faddeev formalism. The measured integrated cross section over the quasifree peak is $20.5 \pm 0.5 \text{(stat)} \pm 1.1 \text{(sys)}$ mb/sr$^2$ in comparison with the theory prediction of 20.1 mb/sr$^{2}$. These results validate our technique for determining the beam-target luminosity in neutron-deuteron breakup measurements., Comment: 23 pages, 12 figures, published in Physical Review C

Published
2020
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18. A Functional Form for Liquid Scintillator Pulse Shapes

Author

Friesen, F. Q. L and Howell, C. R.

Subjects
Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract

Digitization of detector signals enables analysis of the original waveform to extract timing, particle identification, and energy deposition information. Here we present the use of analytical functions based on sigmoids to model and fit such pulse shapes from liquid organic scintillators, though the method should also be applicable to other detector systems. Neutron and gamma interactions in NE213 detectors were digitized from the phototube anode and fit using a sigmoid-based function. The acuity of the fit in extracting timing information and performing neutron-gamma pulse-shape discrimination are presented and discussed., Comment: Accepted to NIM section A: NIMA-D-19-01031R1

Published
2019
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19. Compton scattering from $^4$He at the TUNL HI$\gamma$S facility

Author

Li, X., Ahmed, M. W., Banu, A., Bartram, C., Crowe, B., Downie, E. J., Emamian, M., Feldman, G., Gao, H., Godagama, D., Grießhammer, H. W., Howell, C. R., Karwowski, H. J., Kendellen, D. P., Kovash, M. A., Leung, K. K. H., Markoff, D., Mikhailov, S., Pywell, R. E., Sikora, M. H., Silano, J. A., Sosa, R. S., Spraker, M. C., Swift, G., Wallace, P., Weller, H. R., Whisnant, C. S., Wu, Y. K., and Zhao, Z. W.

Subjects
Nuclear Experiment, High Energy Physics - Experiment, High Energy Physics - Phenomenology, Nuclear Theory
Abstract

Differential cross sections for elastic Compton scattering from $^4$He have been measured with high statistical precision at the High Intensity $\gamma$-ray Source at laboratory scattering angles of $55^\circ$, $90^\circ$, and $125^\circ$ using a quasi-monoenergetic photon beam with a weighted mean energy value of $81.3$ MeV. The results are compared to previous measurements and similar fore-aft asymmetry in the angular distribution of the differential cross sections is observed. This experimental work is expected to strongly motivate the development of effective-field-theory calculations of Compton scattering from $^4$He to fully interpret the data., Comment: 8 pages, 8 figures

Published
2019
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20. Conceptual design and first results for a neutron detector with interaction localization capabilities

Author

Heideman, J., Perez-Loureiro, D., Grzywacz, R., Thornsberry, C. R., Chan, J., Heilbronn, L. H., Neupane, S. K., Schmitt, K., Rajabali, M. M., Engelhardt, A. R., Howell, C. W., Mostella, L. D., Owens, J. S., Shadrick, S. C., Peters, E. E., Ramirez, A. P. D., Yates, S. W., and Vaigneur, K.

Subjects
Physics - Instrumentation and Detectors
Abstract

A new high-precision detector for studying neutrons from beta-delayed neutron emission and direct reaction studies is proposed. The Neutron dEtector with Xn Tracking (NEXT) array is designed to maintain high intrinsic neutron detection efficiency while reducing uncertainties in neutron energy measurements. A single NEXT module is composed of thin segments of plastic scintillator, each optically separated, capable of neutron-gamma discrimination. Each segmented module is coupled to position sensitive photodetectors enabling the high-precision determination of neutron time of arrival and interaction position within the active volume. A design study has been conducted based on simulations and experimental tests leading to the construction of prototype units. First results from measurements using a $^{252}$Cf neutron source and accelerator-produced monoenergetic neutrons are presented., Comment: 17 pages, 21 Figures

Published
2019
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21. Time Projection Chamber (TPC) Detectors for Nuclear Astrophysics Studies With Gamma Beams

Author

Gai, M., Schweitzer, D., Stern, S. R., Young, A. H., Smith, R., Cwiok, M., Bihalowicz, J. S., Czyrkowski, H., Dabrowski, R., Dominik, W., Fijalkowska, A., Janas, Z., Janiak, L., Korgul, A., Matulewicz, T., Mazzocchi, C., Pfuetzner, M., Zaremba, M., Balabanski, D., Gheorghe, I., Matei, C., Tesileanu, O., Zamfir, N. V., Ahmed, M. W., Henshaw, S. S., Howell, C. R., Mueller, J. M., Myers, L. S., Stave, S., Sun, C., Weller, H. R., Wu, Y. K., Breskin, A., Dangendorf, V., Tittelmeier, K., and Freer, M.

Subjects
Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract

Gamma-Beams at the HIgS facility in the USA and anticipated at the ELI-NP facility, now constructed in Romania, present unique new opportunities to advance research in nuclear astrophysics; not the least of which is resolving open questions in oxygen formation during stellar helium burning via a precise measurement of the 12C(a,g) reaction. Time projection chamber (TPC) detectors operating with low pressure gas (as an active target) are ideally suited for such studies. We review the progress of the current research program and plans for the future at the HI{\gamma}S facility with the optical readout TPC (O-TPC) and the development of an electronic readout TPC for the ELI-NP facility (ELITPC)., Comment: Contribution Symposium on Radiation Measurements and Applications (SORMA XVII), June 11 - June 14 , 2018, University of Michigan, Ann Arbor

Published
2018

22. Hello, You've been hacked: a study of victim notification preferences.

Author

Muniz, Caitlyn N., Fisher, Taylor, Smith, Katelyn, Ali, Roan, Howell, C. Jordan, and Maimon, David

Subjects
COMPUTER crimes, IDENTITY theft, FRAUD
Abstract

In the context of identity theft, raising victims' awareness is crucial to mitigate ensuing fraud. This study employs a two-part approach to evaluate the mode and content preferences for identity theft victimization notifications as well as recipients' willingness to engage with these notifications. Notably, results underscore young adults' inclination toward text message notifications featuring legitimizing credentials, signifying authenticity, and fostering rapid responses. Surprisingly, a randomized controlled trial yields a counterintuitive finding: actual identity theft victims display restrained interaction with text-based notifications, regardless of credential presence. The implications of these unexpected patterns guide theory and aid in the development of proactive policy initiatives. [ABSTRACT FROM AUTHOR]

Published
2025
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23. Violations of Emergent Norms Regarding COVID-19 Mitigation and Social Hygiene: An Application of Agnew's General Theory of Crime.

Author

Kabiri, Saeed, Sharepour, Mahmoud, Howell, C. Jordan, Wellen, Hadley, Smith, Hayden P., Cochran, John K., Shadmanfaat, Seyyedeh Masoomeh, and Andersen, Tia Stevens

Subjects
HIGH school students, SOCIAL norms, COVID-19, HYGIENE, PUBLIC schools
Abstract

This study examines self-reported violations of emergent norms and regulations regarding COVID-19 mitigation and social hygiene practices among a sample of high school students randomly selected from public schools in Rasht, Iran. The study seeks to explain these COVID-19 ordinance violations through the application of Agnew's general integrated theory of crime. Findings demonstrate that life domains, motivations, and constraints have a direct effect on COVID-19 misbehavior. Moreover, life domains have an indirect effect on COVID-19 misbehavior through both constraints and motivations. Finally, the relationship between motivations and COVID-19 misbehavior is moderated by the peers domain, whereas the relationship between constraints and COVID-19 misbehavior is moderated by the family domain and school domain. [ABSTRACT FROM AUTHOR]

Published
2025
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27. Fundamental Symmetries, Neutrons, and Neutrinos (FSNN): Whitepaper for the 2023 NSAC Long Range Plan

Author

Acharya, B, primary, Adams, C, additional, Aleksandrova, A, additional, Alfonso, K, additional, An, P, additional, Baessler, S, additional, Balantekin, A, additional, Barbeau, P, additional, Bellini, F, additional, Bellini, V, additional, Beminiwatha, R, additional, Bernauer, J, additional, Bhattacharya, T, additional, Bishof, M, additional, Bolotnikov, A, additional, Breur, P, additional, Brodeur, M, additional, Brodsky, J, additional, Broussard, L, additional, Brunner, T, additional, Burdette, D, additional, Caylor, J, additional, Chiu, M, additional, Cirigliano, V, additional, Clark, J, additional, Clayton, S, additional, Daniels, T, additional, Darroch, L, additional, Davoudi, Z, additional, de Gouvea, A, additional, Dekens, W, additional, Demarteau, M, additional, DeMille, D, additional, Deshpande, A, additional, Detwiler, J, additional, Dodson, G, additional, Kolinski, M, additional, Elliott, S, additional, Engel, J, additional, Erler, J, additional, Filippone, B, additional, Fomin, N, additional, Formaggio, J, additional, Fry, J, additional, Fujikawa, B, additional, Fuller, G, additional, Fuyuto, K, additional, Gallant, A, additional, Gallina, G, additional, Garcia Ruiz, A, additional, Garcia Ruiz, R, additional, Gardner, S, additional, Gonzalez, F, additional, Gratta, G, additional, Gruszko, J, additional, Gudkov, V, additional, Giuseppe, V, additional, Gutierrez, T, additional, Hansen, E, additional, Hardy, C, additional, Haxton, W, additional, Hayer, L, additional, Hedges, S, additional, Heeger, K, additional, Heffner, M, additional, Heise, J, additional, Henning, R, additional, Hergert, H, additional, Hertzog, D, additional, Hervas Aguilar, D, additional, Holt, J, additional, Hoogerheide, S, additional, Hoppe, E, additional, Horoi, M, additional, Howell, C, additional, Huang, M, additional, Hutzler, N, additional, Imam, K, additional, Ito, T, additional, Jamil, A, additional, Janssens, R, additional, Jayich, A, additional, Kammel, P, additional, Liu, K, additional, Khachatryan, V, additional, King, P, additional, Klein, J, additional, Kneller, J, additional, Kolomensky, Y, additional, Korsch, W, additional, Krucken, R, additional, Kumar, K, additional, Launey, K, additional, Lawrence, D, additional, Leach, K, additional, Lehnert, B, additional, Lenardo, B, additional, Li, Z, additional, Lin, H, additional, Longfellow, B, additional, Lopez-Caceres, S, additional, Lunardini, C, additional, MacLellan, R, additional, Markoff, D, additional, Maruyama, R, additional, Mathews, D, additional, Melconian, D, additional, Mereghetti, E, additional, Mohanmurthy, P, additional, Moore, D, additional, Mueller, P, additional, Mumm, H, additional, Nazarewicz, W, additional, Newby, J, additional, Nicholson, A, additional, Novitski, E, additional, Nzobadila Ondze, J, additional, O'Donnell, T, additional, Orebi Gann, G, additional, Orrell, J, additional, Ouellet, J, additional, Parno, D, additional, Paschke, K, additional, Pastore, S, additional, Pattie Jr, R, additional, Petrov, A, additional, Pitt, M, additional, Plaster, B, additional, Pocanic, D, additional, Pocar, A, additional, Radford, D, additional, Rahangdale, H, additional, Rasco, B, additional, Rasiwala, H, additional, Redwine, R, additional, Ritz, A, additional, Rogers, L, additional, Ron, G, additional, Saldanha, R, additional, Sangiorgio, S, additional, Sargsyan, G, additional, Saunders, A, additional, Savard, G, additional, Schaper, D, additional, Scholberg, K, additional, Scielzo, N, additional, Seng, C, additional, Shindler, A, additional, Singh, J, additional, Singh, M, additional, Singh, V, additional, Snow, W, additional, Soma, A, additional, Souder, P, additional, Speller, D, additional, Stachurska, J, additional, Surukuchi, P, additional, Tapia Oregui, B, additional, Tomalak, O, additional, Torres, J, additional, Tyuka, O, additional, VanDevender, B, additional, Varriano, L, additional, Vogt, R, additional, Walker-Loud, A, additional, Wamba, K, additional, Watkins, S, additional, Wietfeldt, F, additional, Williams, W, additional, Wilson, J, additional, Winslow, L, additional, Yan, X, additional, Yang, L, additional, Young, A, additional, Zheng, X, additional, and Zhou, Y, additional

Published
2023
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28. The Present and Future of QCD: QCD Town Meeting White Paper -- An INput to the 2023 NSAC Long Range Plan

Author

Achenbach, P, primary, Adhikari, D, additional, Afanasev, A, additional, Afzal, F, additional, Aidala, C, additional, Al-bataineh, A, additional, Almaaloi, D, additional, Amaryan, M, additional, Androic, D, additional, Armstrong, W, additional, Arriatia, M, additional, Arrington, J, additional, Asaturyan, A, additional, Aschenauer, E, additional, Atac, H, additional, Avakian, H, additional, Averett, T, additional, Ayerbe Gayoso, C, additional, Bai, X, additional, Barish, K, additional, Barnea, N, additional, Basar, G, additional, Battaglieri, M, additional, Baty, A, additional, Bautista, I, additional, Bazilevsky, A, additional, Beattie, C, additional, Behera, S, additional, Bellini, V, additional, Bellwied, R, additional, Benesch, J, additional, Benmokhtar, F, additional, Bernardes, C, additional, Bernauer, J, additional, Bhatt, H, additional, Bhatta, S, additional, Boer, M, additional, Boettcher, T, additional, Bogacz, S, additional, Bossi, H, additional, Brandenburg, J, additional, Brash, E, additional, Briceno, R, additional, Briscoe, W, additional, Brodsky, S, additional, Brown, D, additional, Burkert, V, additional, Caines, H, additional, Cali, I, additional, Camsonne, A, additional, Carman, D, additional, Caylor, J, additional, Cerci, S, additional, Chamizo Llatas, M, additional, Chen, J, additional, Chen, Y, additional, Chien, Y, additional, Chou, P, additional, Chu, X, additional, Chudakov, E, additional, Cline, E, additional, Cloet, I, additional, Cole, P, additional, Conners, M, additional, Constantinou, M, additional, Cosyn, W, additional, Covrig Dusa, S, additional, Cruz-Torres, R, additional, D'Alesio, U, additional, da Silva, C, additional, Davoudi, Z, additional, Dean, C, additional, Dean, D, additional, Demarteau, M, additional, Deshpande, A, additional, Detmold, W, additional, Deur, A, additional, Devkota, B, additional, Dhital, S, additional, Diefenthaler, M, additional, Dobbs, S, additional, Doring, M, additional, Dong, X, additional, Dotel, R, additional, Dow, K, additional, Downie, E, additional, Drachenberg, J, additional, Dumitru, A, additional, Dunlop, J, additional, Dupre, R, additional, Durham, J, additional, Dutta, D, additional, Edwards, R, additional, Ehlers, R, additional, El Fassi, L, additional, Elaasar, M, additional, Elouadrhiri, L, additional, Engelhardt, M, additional, Ent, R, additional, Esumi, S, additional, Evdokimov, O, additional, Eyser, O, additional, Fanelli, C, additional, Fatemi, R, additional, Fernando, I, additional, Flor, F, additional, Fomin, N, additional, Frawley, A, additional, Federico, T, additional, Fries, R, additional, Gal, C, additional, Gamage, B, additional, Gamberg, L, additional, Gao, H, additional, Gaskell, D, additional, Geurts, F, additional, Ghandilyan, Y, additional, Gilman, R, additional, Gleason, C, additional, Gnanvo, K, additional, Gothe, R, additional, Greene, S, additional, Griesshammer, H, additional, Grossberndt, S, additional, Grube, B, additional, Hackett, D, additional, Hague, T, additional, Hakobyan, H, additional, Hansen, J, additional, Hatta, Y, additional, Hattawy, M, additional, Havener, L, additional, Hen, O, additional, Henry, W, additional, Higinbotham, D, additional, Hobbs, T, additional, Hodges, A, additional, Holmstrom, T, additional, Hong, B, additional, Horn, T, additional, Howell, C, additional, Huang, H, additional, Huang, M, additional, Huang, S, additional, Huber, G, additional, Hyde, C, additional, Isupov, E, additional, Jacobs, P, additional, Jalilian-Marian, J, additional, Jentsch, A, additional, Jheng, H, additional, Ji, C, additional, Ji, X, additional, Jia, J, additional, Jones, D, additional, Jones, M, additional, Kalantarians, N, additional, Kalicy, G, additional, Kang, Z, additional, Karthein, J, additional, Keller, D, additional, Keppel, C, additional, Khachartryan, V, additional, Kharzeev, D, additional, Kim, M, additional, Kim, Y, additional, King, P, additional, Kinney, E, additional, Klein, S, additional, Ko, H, additional, Koch, V, additional, Kohl, M, additional, Kovchegov, Y, additional, Krintiras, G, additional, Kubarovsky, V, additional, Kuhn, S, additional, Kumar, K, additional, Kutz, T, additional, Lajoie, J, additional, Lauret, J, additional, Lavrukhin, I, additional, Lawrence, D, additional, Lee, J, additional, Lee, K, additional, Lee, S, additional, Lee, Y, additional, Li, S, additional, Li, W, additional, Li, X, additional, Liao, J, additional, Lin, H, additional, Lisa, M, additional, Liu, K, additional, Liu, M, additional, Liu, T, additional, Liuti, S, additional, Liyanage, N, additional, Llope, W, additional, Loizides, C, additional, Longo, R, additional, Lorenzon, W, additional, Luo, X, additional, Ma, R, additional, McKinnon, B, additional, Meekins, D, additional, Mehtar-Tani, Y, additional, Melnitchouk, W, additional, Metz, A, additional, Meyer, C, additional, Meziani, Z, additional, Michaels, R, additional, Milner, R, additional, Mkrtchyan, H, additional, Mohanmurthy, P, additional, Mohanty, B, additional, Mokeev, V, additional, Mooney, I, additional, Morningstar, C, additional, Morrison, D, additional, Muller, B, additional, Mukherjee, S, additional, Mulligan, J, additional, Munoz Camacho, C, additional, Murillo Quijada, J, additional, Murray, M, additional, Nadeeshani, S, additional, Nadel-Turonski, P, additional, Nam, J, additional, Nattrass, C, additional, Nijs, G, additional, Norohna, J, additional, Noronha-Hostler, J, additional, Novitzky, N, additional, Nycz, M, additional, Olness, F, additional, Osborn, J, additional, Pak, R, additional, Pandey, B, additional, Paolone, M, additional, Papandreou, Z, additional, Paquet, J, additional, Park, S, additional, Paschke, K, additional, Pasquini, B, additional, Pasyuk, E, additional, Patel, T, additional, Patton, A, additional, Paudel, C, additional, Peng, C, additional, Peng, J, additional, Pereira Da Costa, H, additional, Perepelitsa, D, additional, Peters, M, additional, Petreczky, P, additional, Pisarski, R, additional, Pitonyak, D, additional, Ploskon, M, additional, Posik, M, additional, Poudel, J, additional, Pradhan, R, additional, Prokudin, A, additional, Pruneau, C, additional, Putschke, J, additional, Pybus, J, additional, Qiu, J, additional, Rajagopal, K, additional, Ratti, C, additional, Read, K, additional, Reed, R, additional, Richards, D, additional, Riedl, C, additional, Ringer, F, additional, Rinn, T, additional, Rittenhouse West, J, additional, Roche, J, additional, Rodas, A, additional, Roland, G, additional, Romero-Lopez, F, additional, Rossi, P, additional, Rostomyan, T, additional, Ruan, L, additional, Ruimi, O, additional, Saha, N, additional, Sahoo, N, additional, Sakaguchi, T, additional, Salazar, F, additional, Salgado, C, additional, Salme, G, additional, Salur, S, additional, Santiesteban, S, additional, Sargsian, M, additional, Sarsour, M, additional, Sato, N, additional, Satogata, T, additional, Sawada, S, additional, Schafer, T, additional, Scheihing-Hitschfeld, B, additional, Schenke, B, additional, Schindler, S, additional, Schmidt, A, additional, Seidl, R, additional, Sabestari, M, additional, Shanahan, P, additional, Shen, C, additional, Sheng, T, additional, Shepherd, M, additional, M Sickles, A, additional, Sievert, M, additional, Smith, K, additional, Song, Y, additional, Sorensen, A, additional, Souder, P, additional, Spareveris, N, additional, Srednyak, S, additional, Stahl Leiton, A, additional, Stasto, A, additional, Steinberg, P, additional, Stepanyan, S, additional, Stephanov, M, additional, Stevens, J, additional, Stewart, D, additional, Stewart, I, additional, Stojanovic, M, additional, Strakovsky, I, additional, Strauch, S, additional, Strickland, M, additional, Sunar Cerci, D, additional, Suresh, M, additional, Surrow, B, additional, Syritsyn, S, additional, Szczepaniak, A, additional, Tadepalli, A, additional, H Tang, A, additional, Tapia Takaki, J, additional, Tarnowsky, T, additional, Tawfik, A, additional, Taylor, M, additional, Tennant, C, additional, Thiel, A, additional, Thomas, D, additional, Tian, Y, additional, Timmins, A, additional, Tribedy, P, additional, Tu, Z, additional, Tuo, S, additional, Ullrich, T, additional, Umaka, E, additional, Ghimire, N, additional, Vary, J, additional, Velkovska, J, additional, Venugopalan, R, additional, Vijayakumar, A, additional, Vitev, I, additional, Vogelsang, W, additional, Vogt, R, additional, Vossen, A, additional, Voutier, E, additional, Vovchenko, V, additional, Walker-Loud, A, additional, Wang, F, additional, Wang, J, additional, Wang, X, additional, Weinstein, L, additional, Wenaus, T, additional, Weyhmiller, S, additional, Wissink, S, additional, Wojtsekhowski, B, additional, Wong, C, additional, Wood, M, additional, Wunderlich, Y, additional, Wyslouch, B, additional, Xiao, B, additional, Xie, W, additional, Xiong, W, additional, Xu, N, additional, Xu, Q, additional, Xu, Z, additional, Yaari, D, additional, Yao, X, additional, Ye, Z, additional, Yero, C, additional, Yuan, F, additional, Zajc, W, additional, Zhang, C, additional, Zhang, J, additional, Zhao, F, additional, Zhao, Y, additional, Zhao, Z, additional, Zheng, X, additional, and Zhou, J, additional

Published
2023
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29. Second Report of the Nuclear Data Subcommittee of the Nuclear Science Advisory Committee

Author

Bernstein, L, primary, Bostelmann, F, additional, Carpenter, M, additional, Chadwick, M, additional, Fratoni, M, additional, Hawari, A, additional, Heilbronn, L, additional, Howell, C, additional, Ressler, J, additional, Keppel, C, additional, Koning, A, additional, LaBel, K, additional, Turflinger, T, additional, Nesaraja, C, additional, Qaim, S, additional, Romano, C, additional, Spyrou, A, additional, Siem, S, additional, Vermeulen, C, additional, and Vogt, R, additional

Published
2023
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33. International workshop on next generation gamma-ray source

Author

Howell, C. R., Ahmed, M. W., Afanasev, A., Alesini, D., Annand, J. R. M., Aprahamian, A., Balabanski, D. L., Benson, S. V., Bernstein, A., Brune, C. R., Byrd, J., Carlsten, B. E., Champagne, A. E., Chattopadhyay, S., Davis, D., Downie, E. J., Durham, J. M., Feldman, G., Gao, H., Geddes, C. G. R., Grießhammer, H. W., Hajima, R., Hao, H., Hornidge, D., Isaak, J., Janssens, R. V. F., Kendellen, D. P., Kovash, M. A., Martel, P. P., Meißner, U.-G., Miskimen, R., Pasquini, B., Phillips, D. R., Pietralla, N., Savran, D., Schindler, M. R., Sikora, M. H., Snow, W. M., Springer, R. P., Sun, C., Tang, C., Tiburzi, B., Tonchev, A. P., Tornow, W., Ur, C. A., Wang, D., Weller, H. R., Werner, V., Wu, Y. K., Yan, J., Zhao, Z., Zilges, A., Zomer, F., Howell, C. R., Ahmed, M. W., Afanasev, A., Alesini, D., Annand, J. R. M., Aprahamian, A., Balabanski, D. L., Benson, S. V., Bernstein, A., Brune, C. R., Byrd, J., Carlsten, B. E., Champagne, A. E., Chattopadhyay, S., Davis, D., Downie, E. J., Durham, J. M., Feldman, G., Gao, H., Geddes, C. G. R., Grießhammer, H. W., Hajima, R., Hao, H., Hornidge, D., Isaak, J., Janssens, R. V. F., Kendellen, D. P., Kovash, M. A., Martel, P. P., Meißner, U.-G., Miskimen, R., Pasquini, B., Phillips, D. R., Pietralla, N., Savran, D., Schindler, M. R., Sikora, M. H., Snow, W. M., Springer, R. P., Sun, C., Tang, C., Tiburzi, B., Tonchev, A. P., Tornow, W., Ur, C. A., Wang, D., Weller, H. R., Werner, V., Wu, Y. K., Yan, J., Zhao, Z., Zilges, A., and Zomer, F.

Published
2024

34. Measurement of the half-life of the T=$\frac{1}{2}$ mirror decay of $^{19}$Ne and its implication on physics beyond the standard model

Author

Broussard, L. J., Back, H. O., Boswell, M. S., Crowell, A. S., Dendooven, P., Giri, G. S., Howell, C. R., Kidd, M. F., Jungmann, K., Kruithof, W. L., Mol, A., Onderwater, C. J. G., Pattie Jr., R. W., Shidling, P. D., Sohani, M., van der Hoek, D. J., Rogachevskiy, A., Traykov, E., Versolato, O. O., Willmann, L., Wilschut, H. W., and Young, A. R.

Subjects
Nuclear Experiment
Abstract

The $\frac{1}{2}^+ \rightarrow \frac{1}{2}^+$ superallowed mixed mirror decay of $^{19}$Ne to $^{19}$F is excellently suited for high precision studies of the weak interaction. However, there is some disagreement on the value of the half-life. In a new measurement we have determined this quantity to be $T_{1/2}$ = $17.2832 \pm 0.0051_{(stat)}$ $\pm 0.0066_{(sys)}$ s, which differs from the previous world average by 3 standard deviations. The impact of this measurement on limits for physics beyond the standard model such as the presence of tensor currents is discussed., Comment: 5 pages, 3 figures, 1 table

Published
2013
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36. Measurement of the elastic scattering cross section of neutrons from argon and neon

Author

MacMullin, S., Kidd, M., Henning, R., Tornow, W., Howell, C. R., and Brown, M.

Subjects
Nuclear Experiment
Abstract

Background: The most significant source of background in direct dark matter searches are neutrons that scatter elastically from nuclei in the detector's sensitive volume. Experimental data for the elastic scattering cross section of neutrons from argon and neon, which are target materials of interest to the dark matter community, were previously unavailable. Purpose: Measure the differential cross section for elastic scattering of neutrons from argon and neon in the energy range relevant to backgrounds from (alpha,n) reactions in direct dark matter searches. Method: Cross-section data were taken at the Triangle Universities Nuclear Laboratory (TUNL) using the neutron time-of-flight technique. These data were fit using the spherical optical model. Results: The differential cross section for elastic scatting of neutrons from neon at 5.0 and 8.0 MeV and argon at 6.0 MeV was measured. Optical-model parameters for the elastic scattering reactions were determined from the best fit to these data. The total elastic scattering cross section for neon was found to differ by 6% at 5.0 MeV and 13% at 8.0 MeV from global optical-model predictions. Compared to a local optical-model for 40Ar, the elastic scattering cross section was found to differ from the data by 8% at 6.0 MeV. Conclusions: These new data are important for improving Monte-Carlo simulations and background estimates for direct dark matter searches and for benchmarking optical models of neutron elastic scattering from these nuclei.

Published
2012
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37. Virtual Compton Scattering and the Generalized Polarizabilities of the Proton at Q^2=0.92 and 1.76 GeV^2

Author

Fonvieille, H., Laveissiere, G., Degrande, N., Jaminion, S., Jutier, C., Todor, L., Di Salvo, R., Van Hoorebeke, L., Alexa, L. C., Anderson, B. D., Aniol, K. A., Arundell, K., Audit, G., Auerbach, L., Baker, F. T., Baylac, M., Berthot, J., Bertin, P. Y., Bertozzi, W., Bimbot, L., Boeglin, W. U., Brash, E. J., Breton, V., Breuer, H., Burtin, E., Calarco, J. R., Cardman, L. S., Cavata, C., Chang, C. -C., Chen, J. -P., Chudakov, E., Cisbani, E., Dale, D. S., deJager, C. W., De Leo, R., Deur, A., d'Hose, N., Dodge, G. E., Domingo, J. J., Elouadrhiri, L., Epstein, M. B., Ewell, L. A., Finn, J. M., Fissum, K. G., Fournier, G., Frois, B., Frullani, S., Furget, C., Gao, H., Gao, J., Garibaldi, F., Gasparian, A., Gilad, S., Gilman, R., Glamazdin, A., Glashausser, C., Gomez, J., Gorbenko, V., Grenier, P., Guichon, P. A. M., Hansen, J. O., Holmes, R., Holtrop, M., Howell, C., Huber, G. M., Hyde, C. E., Incerti, S., Iodice, M., Jardillier, J., Jones, M. K., Kahl, W., Kato, S., Katramatou, A. T., Kelly, J. J., Kerhoas, S., Ketikyan, A., Khayat, M., Kino, K., Kox, S., Kramer, L. H., Kumar, K. S., Kumbartzki, G., Kuss, M., Leone, A., LeRose, J. J., Liang, M., Lindgren, R. A., Liyanage, N., Lolos, G. J., Lourie, R. W., Madey, R., Maeda, K., Malov, S., Manley, D. M., Marchand, C., Marchand, D., Margaziotis, D. J., Markowitz, P., Marroncle, J., Martino, J., McCormick, K., McIntyre, J., Mehrabyan, S., Merchez, F., Meziani, Z. E., Michaels, R., Miller, G. W., Mougey, J. Y., Nanda, S. K., Neyret, D., Offermann, E. A. J. M., Papandreou, Z., Pasquini, B., Perdrisat, C. F., Perrino, R., Petratos, G. G., Platchkov, S., Pomatsalyuk, R., Prout, D. L., Punjabi, V. A., Pussieux, T., Quemener, G., Ransome, R. D., Ravel, O., Real, J. S., Renard, F., Roblin, Y., Rowntree, D., Rutledge, G., Rutt, P. M., Saha, A., Saito, T., Sarty, A. J., Serdarevic, A., Smith, T., Smirnov, G., Soldi, K., Sorokin, P., Souder, P. A., Suleiman, R., Templon, J. A., Terasawa, T., Tieulent, R., Tomasi-Gustaffson, E., Tsubota, H., Ueno, H., Ulmer, P. E., Urciuoli, G. M., Vanderhaeghen, M., Van der Meer, R. L. J., Van De Vyver, R., Vernin, P., Vlahovic, B., Voskanyan, H., Voutier, E., Watson, J. W., Weinstein, L. B., Wijesooriya, K., Wilson, R., Wojtsekhowski, B. B., Zainea, D. G., Zhang, W. -M., Zhao, J., and Zhou, Z. -L.

Subjects
Nuclear Experiment, High Energy Physics - Experiment
Abstract

Virtual Compton Scattering (VCS) on the proton has been studied at Jefferson Lab using the exclusive photon electroproduction reaction (e p --> e p gamma). This paper gives a detailed account of the analysis which has led to the determination of the structure functions P_LL-P_TT/epsilon and P_LT, and the electric and magnetic generalized polarizabilities (GPs) alpha_E(Q^2) and beta_M(Q^2) at values of the four-momentum transfer squared Q^2= 0.92 and 1.76 GeV^2. These data, together with the results of VCS experiments at lower momenta, help building a coherent picture of the electric and magnetic GPs of the proton over the full measured Q^2-range, and point to their non-trivial behavior., Comment: version 2: modified according to PRC Editor's and Referee's recommendations. Archival paper for the E93-050 experiment at JLab Hall A. 28 pages, 23 figures, 5 cross-section tables. To be submitted to Phys.Rev.C

Published
2012
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38. Cross Section Measurement of 9Be(\gamma,n)8Be and Implications for \alpha+\alpha+n -> 9Be in the r-Process

Author

Arnold, C. W., Clegg, T. B., Iliadis, C., Karwowski, H. J., Rich, G. C., Tompkins, J. R., and Howell, C. R.

Subjects
Nuclear Experiment
Abstract

Models of the r-process are sensitive to the production rate of 9Be because, in explosive environments rich in neutrons, alpha(alpha n,gamma)9Be is the primary mechanism for bridging the stability gaps at A=5 and A=8. The alpha(alpha n,gamma)9Be reaction represents a two-step process, consisting of alpha+alpha -> 8Be followed by 8Be(n,gamma)9Be. We report here on a new absolute cross section measurement for the 9Be(gamma,n)8Be reaction conducted using a highly-efficient, 3He-based neutron detector and nearly-monoenergetic photon beams, covering energies from E_gamma = 1.5 MeV to 5.2 MeV, produced by the High Intensity gamma-ray Source of Triangle Universities Nuclear Laboratory. In the astrophysically important threshold energy region, the present cross sections are 40% larger than those found in most previous measurements and are accurate to +/- 10% (95% confidence). The revised thermonuclear alpha(alpha n,gamma)9Be reaction rate could have implications for the r-process in explosive environments such as Type II supernovae., Comment: 26 pages, 10 figures

Published
2011
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39. Measurements of the 48Ca({\gamma},n) Reaction

Author

Tompkins, J. R., Arnold, C. W., Karwowski, H. J., Rich, G. C., Sobotka, L. G., and Howell, C. R.

Subjects
Nuclear Experiment
Abstract

The 48Ca({\gamma},n) cross section was measured using {\gamma}-ray beams of energies between 9.5 and 15.3 MeV generated at the Triangle Universities Nuclear Laboratory (TUNL) high-intensity {\gamma}-ray source (HI{\gamma}S). Prior to this experiment, no direct measurements had been made with {\gamma}-ray beams of sufficiently low energy spread to observe structure in this energy range. The cross sections were measured at thirty-four different {\gamma}-ray energies with an enriched 48Ca target. Neutron emission is the dominant decay mechanism in the measured energy range that spans from threshold, across the previously identified M1 strength, and up the low-energy edge of the E1 giant dipole resonance (GDR). This work found B(M 1) = 6.8 \pm 0.5 {\mu}N2 for the 10.23 MeV resonance, a value greater than previously measured. Structures in the cross section commensurate with extended random-phase approximation (ERPA) calculations have also been observed whose magnitudes are in agreement with existing data., Comment: 8 pages, 6 figures

Published
2011
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40. Development of a mini-PET Detector based on Silicon Photomultiplier Arrays for Plant Imaging Applications

Author

Barbosa, F., Dong, H., Kross, B., Lee, S. J., Mack, Y., McKisson, J., Weisenberger, A, Xi, W., Zorn, C., Majewsk, S., Stolin, A., Howell, C. R., Crowell, A. S., Reis, C. D., and Smith, M. F.

Subjects
Physics - Instrumentation and Detectors
Abstract

A mini-PET style detector system is being developed for a plant imaging application with a compact array of silicon photomultipliers (SiPM) replacing position sensitive photomultipliers (PSPMT). In addition to compactness, the use of SiPMs will allow imaging setups involving high strength MRI-type magnetic fields. The latter will allow for better position resolution of the initial positron annihilations in the plant tissue. In the present work, prototype arrays are tested for the uniformity of their response as it is known that PSPMTs require significant gain compensation on the individual channels to achieve an improved uniformity in response. The initial tests indicate a high likelihood that the SiPM arrays can be used without any gain compensation., Comment: Presented at 2010 IEEE NSS/MIC Conference, Knoxville, Tennessee, USA, October 30 - November 6, 2010

Published
2011

41. Characterization of an INVS Model IV Neutron Counter for High Precision ($\gamma,n$) Cross-Section Measurements

Author

Arnold, C. W., Clegg, T. B., Karwowski, H. J, Rich, G. C., Tompkins, J. R., and Howell, C. R.

Subjects
Nuclear Experiment
Abstract

A neutron counter designed for assay of radioactive materials has been adapted for beam experiments at TUNL. The cylindrical geometry and 60% maximum efficiency make it well suited for ($\gamma,n$) cross-section measurements near the neutron emission threshold. A high precision characterization of the counter has been made using neutrons from several sources. Using a combination of measurements and simulations, the absolute detection efficiency of the neutron counter was determined to an accuracy of $\pm$ 3% in the neutron energy range between 0.1 and 1 MeV. It is shown that this efficiency characterization is generally valid for a wide range of targets., Comment: 22 pages, 13 figures

Published
2010
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42. A Sacred Evolutionary Cosmos: Philip Sherrard, Theodosius Dobzhansky, and the Theological Challenge of Climate Change.

Author

Howell, C. W.

Subjects
*CLIMATE change, *REDUCTIONISM, *PROGRESSIVISM, *HOSTILITY
Abstract

Philip Sherrard and Theodosius Dobzhansky, both Eastern Orthodox intellectuals, would have agreed on little. While Sherrard rejected modern science, especially evolution, Dobzhansky was one of evolution's leading figures. But Sherrard saw climate change coming and warned of it, whereas Dobzhansky was perhaps too easy in his liberal progressivism. Despite their major differences, however, Dobzhansky and Sherrard both shared a hostility towards reductionism and a mechanistic view of the universe. In studying their ideas and incorporating ecology into the conversation, we can consider different ways to view evolution and climate change. [ABSTRACT FROM AUTHOR]

Published
2024
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43. Response of Vitis vinifera L. cv. Pinotage to Irrigation Strategy and Trellis System in the Breede River Valley Region: Vegetative Growth, Yield and Juice Characteristics.

Author

Howell, C. L. and Myburgh, P. A.

Subjects
*WATER efficiency, *IRRIGATION water, *VITIS vinifera, *WATER restrictions, *RAINFALL
Abstract

Pinotage is a South African bred red wine cultivar and is second only to Shiraz in terms of the country’s wine exports. Since rainfall in the Breede River region is low, vineyards in this region depend on irrigation. The sensitivity of Pinotage/99R to water deficits and the most suitable irrigation strategy during water restrictions were studied in a field trial from 1998/99 until 2000/01. The possibility to produce more grapes with the same volume of irrigation water was also investigated. Irrigation strategies entailed combinations of 50% readily available water (RAW) depletion, 75% RAW depletion and no irrigation between various phenological stages, viz. budbreak, flowering, pea size berries, véraison, 17°B and harvest. Irrigation applied at 50% RAW depletion from budbreak in September until harvest in February was regarded as the control. Each experiment plot was split into a six-strand vertical hedge and a two-tier vertical trellis. The experiment layout was a split plot, randomised block design. Cane mass of grapevines on the two-tier trellis was lower compared to those on the six-strand hedge. Irrigation at 75% RAW depletion level until harvest tended to reduce cane mass compared to more frequent irrigation. Drier soil conditions reduced berry mass, regardless of the trellis system. Sustained water deficits reduced yield, but had little effect on juice acidity and pH. More Pinotage grapes were produced on the two-tier vertical trellis compared to the six-strand hedge with the same amount of irrigation, thereby reducing the blue water footprint and increasing the irrigation water use efficiency substantially. [ABSTRACT FROM AUTHOR]

Published
2024
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44. Review of Indirect Methods Used to Determine the $^1S_0$ Neutron-Neutron Scattering Length

Author

Howell, C. R.

Subjects
Nuclear Experiment
Abstract

We have determined a value for the $^1S_0$ neutron-neutron scattering length ($a_{nn}$) from high-precision measurements of time-of-flight spectra of neutrons from the $^2H(\pi^-,n \gamma)n$ capture reaction. The measurements were done at the Los Alamos Meson Physics Facility by the E1286 collaboration. The high spatial resolution of our gamma-ray detector enabled us to make a detailed assessment of the systematic uncertainties in our techniques. The value obtained in the present work is $a_{nn} = -18$.63 $\pm $0.10 (statistical) $\pm$ 0.44 (systematic) $\pm$ 0.30 (theoretical) fm. This result is consistent with previous determinations of $a_{nn}$ from the $\pi^-d$ capture reaction. We found that the analysis of the data with calculations that use a relativistic phase-space factor gives a more negative value for $a_{nn}$ by 0.33 fm over the analysis done using a nonrelativistic phase-space factor. Combining the present result with the previous ones from $\pi^-d$ capture gives: $a_{nn} = - 18$.63 $\pm$ 0.27 (expt) $\pm$ 0.30 fm (theory). For the first time the combined statistical and systematic experimental uncertainty in $a_{nn}$ is smaller than the theoretical uncertainty and comparable to the uncertainty in the proton-proton $^1S_0$ scattering length ($a_{pp}$). This average value of $a_{nn}$ when corrected for the magnetic-moment interaction of the two neutrons becomes -18.9 $\pm$ 0.4 fm which is 1.6 $\pm$ 0.5 fm different from the recommended value of $a_{pp}$, thereby confirming charge symmetry breaking at the 1% confidence level., Comment: 8 pages, 1 figure and 3 tables

Published
2008

45. Neutron-proton analyzing power at 12 MeV and inconsistencies in parametrizations of nucleon-nucleon data

Author

Braun, R. T., Tornow, W., Howell, C. R., Trotter, D. E. Gonzalez, Roper, C. D., Salinas, F., Setze, H. R., Walter, R. L., and Weisel, G. J.

Subjects
Nuclear Experiment
Abstract

We present the most accurate and complete data set for the analyzing power Ay(theta) in neutron-proton scattering. The experimental data were corrected for the effects of multiple scattering, both in the center detector and in the neutron detectors. The final data at En = 12.0 MeV deviate considerably from the predictions of nucleon-nucleon phase-shift analyses and potential models. The impact of the new data on the value of the charged pion-nucleon coupling constant is discussed in a model study., Comment: Six pages, four figures, one table, to be published in Physics Letters B

Published
2008
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47. Low-Energy Photodisintegration of the Deuteron and Big-Bang Nucleosynthesis

Author

Tornow, W., Czakon, N. G., Howell, C. R., Hutcheson, A., Kelley, J. H., Litvinenko, V. N., Mikhailov, S., Pinayev, I. V., Weisel, G. J., and Witala, H.

Subjects
Nuclear Experiment
Abstract

The photon analyzing power for the photodisintegration of the deuteron was measured for seven gamma-ray energies between 2.39 and 4.05 MeV using the linearly polarized gamma-ray beam of the High-Intensity Gamma-ray Source at the Duke Free-Electron Laser Laboratory. The data provide a stringent test of theoretical calculations for the inverse reaction, the neutron-proton radiative capture reaction at energies important for Big-Bang Nucleosynthesis. Our data are in excellent agreement with potential model and effective field theory calculations. Therefore, the uncertainty in the baryon density obtained from Big-Bang Nucleosynthesis can be reduced at least by 20%., Comment: 5 pages, 5 figures

Published
2003
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48. Effects of the magnetic moment interaction between nucleons on observables in the 3N continuum

Author

Witala, H., Golak, J., Skibinski, R., Howell, C. R., and Tornow, W.

Subjects
Nuclear Theory
Abstract

The influence of the magnetic moment interaction of nucleons on nucleon-deuteron elastic scattering and breakup cross sections and on elastic scattering polarization observables has been studied. Among the numerous elastic scattering observables only the vector analyzing powers were found to show a significant effect, and of opposite sign for the proton-deuteron and neutron-deuteron systems. This finding results in an even larger discrepancy than the one previously established between neutron-deuteron data and theoretical calculations. For the breakup reaction the largest effect was found for the final-state-interaction cross sections. The consequences of this observation on previous determinations of the ^1S_0 scattering lengths from breakup data are discussed., Comment: 24 pages, 6 ps figures, 1 png figure

Published
2003
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50. A New Measurement of the 1S0 Neutron-Neutron Scattering Length using the Neutron-Proton Scattering Length as a Standard

Author

Trotter, D. E. Gonzalez, Salinas, F., Chen, Q., Crowell, A. S., Gloeckle, W., Howell, C. R., Roper, C. D., Schmidt, D., Slaus, I., Tang, H., Tornow, W., Walter, R. L., Witala, H., and Zhou, Z.

Subjects
Nuclear Experiment
Abstract

The present paper reports high-accuracy cross-section data for the 2H(n,nnp) reaction in the neutron-proton (np) and neutron-neutron (nn) final-state-interaction (FSI) regions at an incident mean neutron energy of 13.0 MeV. These data were analyzed with rigorous three-nucleon calculations to determine the 1S0 np and nn scattering lengths, a_np and a_nn. Our results are a_nn = -18.7 +/- 0.6 fm and a_np = -23.5 +/- 0.8 fm. Since our value for a_np obtained from neutron-deuteron (nd) breakup agrees with that from free np scattering, we conclude that our investigation of the nn FSI done simultaneously and under identical conditions gives the correct value for a_nn. Our value for a_nn is in agreement with that obtained in pion-deuteron capture measurements but disagrees with values obtained from earlier nd breakup studies., Comment: 4 pages and 3 figures

Published
1999
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