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1. Stellar s-process neutron capture cross section of Ce isotopes

Author

Sahoo, R. N., Paul, M., Kashiv, Y., Tessler, M., Friedman, M., Halfon, S., Kreisel, A., Shor, A., and Weissman, L.

Subjects
Nuclear Experiment
Abstract

Stellar abundances of cerium are of high current interest based both on observations and theoretical models, especially with regard to the neutron--magic $^{140}$Ce isotope. A large discrepancy of $s-$process stellar models relative to cerium abundance observed in globular clusters was highlighted, pointing to possible uncertainties in experimental nuclear reaction rates. In this work, the stellar neutron capture cross section of the stable cerium isotopes $^{136}$Ce, $^{138}$Ce, $^{140}$Ce, and $^{142}$Ce, were re-measured. A $^{nat}$Ce sample was irradiated with quasi-Maxwellian neutrons at $kT = 34.2$ keV using the $^{7}$Li($p,n$) reaction. The neutron field with an intensity of $3-5 \times 10^{10}$ n/s was produced by irradiating the liquid-lithium target (LiLiT) with a mA proton beam at an energy (1.92 MeV) just above the threshold at Soreq Applied Research Accelerator Facility (SARAF). The activities of the $^{nat}$Ce neutron capture products were measured using a shielded High Purity Germanium detector. Cross sections were extracted relative to that of the $^{197}$Au(n,$\gamma$) reaction and the Maxwellian-averaged cross section (MACS) of the Ce isotopes were derived. The MACS values extracted from this experiment are generally consistent with previous measurements and show for $^{140}$Ce a value $\approx 15$\% smaller than most recent experimental values., Comment: 9 pages, 12 figures. This work is supported in part by the Pazy Foundation (Israel) and the German Israeli Foundation (GIF) under Grant No. I-1500-303.7/2019. M.P. and M.F. acknowledge support by the European Union (ChETEC-INFRA)

Published
2024
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2. Stellar $s$-process neutron capture cross sections of $^{69,71}$Ga

Author

Tessler, M., Paul, M., Halfon, S., Kashiv, Y., Kijel, D., Kreisel, A., Shor, A., and Weissman, L.

Subjects
Nuclear Experiment
Abstract

The stable gallium isotopes, $^{69,71}$Ga, are mostly produced by the weak slow ($s$) process in massive stars. We report here on measurements of astrophysically-relevant neutron capture cross sections of the $^{69,71}$Ga$(n,\gamma)$ reactions. The experiments were performed by the activation technique using a high-intensity ($3-5\times10^{10}$ n/s), quasi-Maxwellian neutron beam that closely mimics conditions of stellar $s$-process nucleosynthesis at $kT \approx$ 40 keV. The neutron field was produced by a mA proton beam at $E_p=1925$ keV (beam power of 2-3 kW) from the Soreq Applied Research Accelerator Facility (SARAF), bombarding the Liquid-Lithium Target (LiLiT). A 473 mg sample of Ga$_2$O$_3$ of natural isotopic composition was activated in the LiLiT neutron field and the activities of $^{70,72}$Ga were measured by decay counting via $\gamma$-spectrometry with a high-purity germanium detector. The Maxwellian-averaged cross sections at $kT$ = 30 keV of $^{69}$Ga and $^{71}$Ga determined in this work are 136(8) mb and 105(7) mb, respectively, in good agreement with previous experimental values. Astrophysical implications of the measurements are discussed.

Published
2022
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3. Stellar $^{36,38}$Ar$(n,\gamma)^{37,39}$Ar reactions and their effect on light neutron-rich nuclide synthesis

Author

Tessler, M., Paul, M., Halfon, S., Meyer, B. S., Pardo, R., Purtschert, R., Rehm, K. E., Scott, R., Weigand, M., Weissman, L., Almaraz-Calderon, S., Avila, M. L., Baggenstos, D., Collon, P., Hazenshprung, N., Kashiv, Y., Kijel, D., Kreisel, A., Reifarth, R., Santiago-Gonzalez, D., Shor, A., Silverman, I., Talwar, R., Veltum, D., and Vondrasek, R.

Subjects
Nuclear Experiment
Abstract

The $^{36}$Ar$(n,\gamma)^{37}$Ar ($t_{1/2}$ = 35 d) and $^{38}$Ar$(n,\gamma)^{39}$Ar (269 y) reactions were studied for the first time with a quasi-Maxwellian ($kT \sim 47$ keV) neutron flux for Maxwellian Average Cross Section (MACS) measurements at stellar energies. Gas samples were irradiated at the high-intensity Soreq applied research accelerator facility-liquid-lithium target neutron source and the $^{37}$Ar/$^{36}$Ar and $^{39}$Ar/$^{38}$Ar ratios in the activated samples were determined by accelerator mass spectrometry at the ATLAS facility (Argonne National Laboratory). The $^{37}$Ar activity was also measured by low-level counting at the University of Bern. Experimental MACS of $^{36}$Ar and $^{38}$Ar, corrected to the standard 30 keV thermal energy, are 1.9(3) mb and 1.3(2) mb, respectively, differing from the theoretical and evaluated values published to date by up to an order of magnitude. The neutron capture cross sections of $^{36,38}$Ar are relevant to the stellar nucleosynthesis of light neutron-rich nuclides; the two experimental values are shown to affect the calculated mass fraction of nuclides in the region A=36-48 during the weak $s$-process. The new production cross sections have implications also for the use of $^{37}$Ar and $^{39}$Ar as environmental tracers in the atmosphere and hydrosphere., Comment: 18 pages + Supp. Mat. (13 pages) Accepted for publication in Phys. Rev. Lett

Published
2018
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4. Stellar 30-keV neutron capture in 94,96Zr and the 90Zr(gamma,n)89Zr photonuclear reaction with a high-power liquid-lithium target

Author

Tessler, M., Paul, M., Arenshtam, A., Feinberg, G., Friedman, M., Halfon, S., Kijel, D., Weissman, L., Aviv, O., Berkovits, D., Eisen, Y., Eliyahu, I., Haquin, G., Kreisel, A., Mardor, I., Shimel, G., Shor, A., Silverman, I., and Yungrais, Z.

Subjects
Nuclear Experiment
Abstract

A high-power Liquid-Lithium Target (LiLiT) was used for the first time for neutron production via the thick-target 7Li(p,n)7Be reaction and quantitative determination of neutron capture cross sections. Bombarded with a 1-2 mA proton beam at 1.92 MeV from the Soreq Applied Research Accelerator Facility (SARAF), the setup yields a 30-keV quasi-Maxwellian neutron spectrum with an intensity of 3-5e10 n/s, more than one order of magnitude larger than present near-threshold 7Li(p,n) neutron sources. The setup was used here to determine the 30-keV Maxwellian averaged cross section (MACS) of 94Zr and 96Zr as 28.0+-0.6 mb and 12.4+-0.5 mb respectively, based on activation measurements. The precision of the cross section determinations results both from the high neutron yield and from detailed simulations of the entire experimental setup. We plan to extend our experimental studies to low-abundance and radioactive targets. In addition, we show here that the setup yields intense high-energy (17.6 and 14.6 MeV) prompt capture gamma-rays from the 7Li(p,gamma)8Be reaction with yields of ~3e8 gammas/s/mA and ~4e8 gammas/s/mA, respectively, evidenced by the 90Zr(gamma,n)89Zr photonuclear reaction., Comment: 20 pages, 5 figures

Published
2015
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5. The 41Ar(n,y)42Ar reaction

Author

Sahoo R. N., Paul M., Köster U., Scott R., Tessler M., Zylstra A., Avila M. L., Dickerson C., Jayatissa H., Kohen M.S., McLain J., Pardo R.C., Rehm K. E., Tolstukhin I., Vondrasek R., Bailey T., Callahan L., Clark A., Collon P., Kashiv Y., and Nelson A.

Subjects
Physics, QC1-999
Abstract

The cross-section of the thermal neutron capture 41Ar(n,γ)42Ar(t1/2=32.9 y) reaction was measured by irradiating a 40Ar sample at the high-flux reactor of Institut Laue-Langevin (ILL) Grenoble, France. The signature of the two-neutron capture has been observed by measuring the growth curve and identifying the 1524.6 keV γ-lines of the shorter-lived 42K(12.4 h) β− daughter of 42Ar. Our preliminary value of the 41Ar(n,γ)42Ar thermal cross section is 240(80) mb at 25.3 meV. For the first time, direct counting of 42Ar was performed using the ultra-high sensitivity technique of noble gas accelerator mass spectrometry (NOGAMS) at Argonne National Laboratory, USA.

Published
2023
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6. 40Ar proposed as probe of neutron-induced reactions in a high-density stellar-like plasma at the National Ignition Facility

Author

Paul M., Sahoo R. N., Tessler M., Jeet J., Velsko C., Zylstra A., Avila M., Dickerson C., Fougères C., Jayatissa H., Pardo R. C., Rehm K. E., Scott R., Tolstukhin I., Vondrasek R., Bailey T., Callahan L., Clark A. M., Collon P., Kashiv Y., Nelson A., Köster U., Hoffmann H. F. R., Pichotta M., Zuber K., Döring T., and Schwengner R.

Subjects
Physics, QC1-999
Abstract

The thermodynamical conditions and the neutron density produced in a laser-induced implosion of a deuterium-tritium (DT) filled capsule at the National Ignition Facility (NIF) are the closest laboratory analog of stellar conditions. We plan to investigate neutron-induced reactions on 40Ar, namely the 40Ar(n, 2n)39Ar(t1/2 =268 y), the 40Ar(n, γ)41Ar(110 min) and the potential rapid two-neutron capture reaction 40Ar(2n, γ)42Ar(33 y) in an Ar-loaded DT capsule. The chemical inertness of noble gas Ar enables reliable collection of the reaction products.

Published
2023
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7. High-power liquid-lithium jet target for neutron production

Author

Halfon, S., Arenshtam, A., Kijel, D., Paul, M., Berkovits, D., Eliyahu, I., Feinberg, G., Friedman, M., Hazenshprung, N., Mardor, I., Nagler, A., Shimel, G., Tessler, M., and Silverman, I.

Subjects
Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract

A compact Liquid-Lithium Target (LiLiT) was built and tested with a high-power electron gun at Soreq Nuclear Research Center. The lithium target, to be bombarded by the high-intensity proton beam of the Soreq Applied Research Accelerator Facility (SARAF), will constitute an intense source of neutrons produced by the 7Li(p,n)7Be reaction for nuclear astrophysics research and as a pilot setup for accelerator-based Boron Neutron Capture Therapy (BNCT). The liquid-lithium jet target acts both as neutron-producing target and beam dump by removing the beam thermal power (>5 kW, >1 MW/cm3) with fast transport. The target was designed based on a thermal model, accompanied by a detailed calculation of the 7Li(p,n) neutron yield, energy distribution and angular distribution. Liquid lithium is circulated through the target loop at ~200oC and generates a stable 1.5 mm-thick film flowing at a velocity up to 7 m/s onto a concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power areal densities of > 4 kW/cm2 and volume power density of ~ 2 MW/cm3 at a lithium flow of ~4 m/s while maintaining stable temperature and vacuum conditions. The LiLiT setup is presently in online commissioning stage for high-intensity proton beam irradiation (1.91- 2.5 MeV, 1-2 mA) at SARAF., Comment: Accepted for publication in Rev. Sci. Instr

Published
2013
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9. 40Ar proposed as probe of neutron-induced reactions in a high-density stellar-like plasma at the National Ignition Facility

Author

Paul, M., Sahoo, S. N., Tessler, M., Jeet, J., Velsko, C., Zylstra, A., Avila, M., Dickerson, C., Fougeres, C., Jayatissa, H., Pardo, R. C., Rehm, K. E., Scott, R., Toltsukhin, I., Vondrasek, R., Bailey, T., Callahan, L., Clark, A. M., Collon, P., Kashiv, Y., Nelson, A., Köster, U., Hoffmann, H. F. R., Pichotta, M., Zuber, K., Döring, T., (0000-0002-7620-8882) Schwengner, R., Paul, M., Sahoo, S. N., Tessler, M., Jeet, J., Velsko, C., Zylstra, A., Avila, M., Dickerson, C., Fougeres, C., Jayatissa, H., Pardo, R. C., Rehm, K. E., Scott, R., Toltsukhin, I., Vondrasek, R., Bailey, T., Callahan, L., Clark, A. M., Collon, P., Kashiv, Y., Nelson, A., Köster, U., Hoffmann, H. F. R., Pichotta, M., Zuber, K., Döring, T., and (0000-0002-7620-8882) Schwengner, R.

Abstract

The thermodynamical conditions of plasma density, temperature, pressure and the neutron density produced in a laser-induced implosion of a deuterium-tritium (DT) filled capsule at the National Ignition Facility (NIF) are the closest laboratory analog of stellar conditions. We plan to investigate neutron-induced reactions on 40Ar, namely the 40Ar(n, 2n)39Ar(t1/2 =268 y), the 40Ar(n,gamma)41Ar(110 min) and the potential rapid two-neutron capture reaction 40Ar(2n,gamma)42Ar(33 y) in the same implosion on an Ar-loaded DT capsule. The chemical inertness of noble gas Ar enables reliable collection of the reaction products. We describe here the technique of Noble-Gas Accelerator Mass Spectrometry (NOGAMS) to be used for ultra-sensitive detection of the long-lived 39Ar and 42Ar at Argonne National Laboratory. A 42Ar(33 y) sample was produced via the slow two-neutron capture reaction 40Ar(2n, gamma)42Ar in a high thermal-neutron flux irradiation. 39Ar and for the first time 42Ar atoms were directly detected in the abundance range 10^-12 -- 10^-13 . The present sensitivity of 42Ar detection is of the order of 104 atoms.

Published
2023

11. The 41Ar(n,y)42Ar reaction.

Author

Sahoo, R. N., Paul, M., Köster, U., Scott, R., Tessler, M., Zylstra, A., Avila, M. L., Dickerson, C., Jayatissa, H., Kohen, M.S., McLain, J., Pardo, R.C., Rehm, K. E., Tolstukhin, I., Vondrasek, R., Bailey, T., Callahan, L., Clark, A., Collon, P., and Kashiv, Y.

Subjects
NUCLEAR cross sections, THERMAL neutron capture, ARGON isotopes, NUCLEAR reactors, MASS spectrometry
Abstract

The cross-section of the thermal neutron capture 41Ar(n,γ)42Ar(t1/2=32.9 y) reaction was measured by irradiating a 40Ar sample at the high-flux reactor of Institut Laue-Langevin (ILL) Grenoble, France. The signature of the two-neutron capture has been observed by measuring the growth curve and identifying the 1524.6 keV γ-lines of the shorter-lived 42K(12.4 h) β− daughter of 42Ar. Our preliminary value of the 41Ar(n,γ)42Ar thermal cross section is 240(80) mb at 25.3 meV. For the first time, direct counting of 42Ar was performed using the ultra-high sensitivity technique of noble gas accelerator mass spectrometry (NOGAMS) at Argonne National Laboratory, USA. [ABSTRACT FROM AUTHOR]

Published
2023
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12. 40Ar proposed as probe of neutron-induced reactions in a high-density stellar-like plasma at the National Ignition Facility.

Author

Paul, M., Sahoo, R. N., Tessler, M., Jeet, J., Velsko, C., Zylstra, A., Avila, M., Dickerson, C., Fougères, C., Jayatissa, H., Pardo, R. C., Rehm, K. E., Scott, R., Tolstukhin, I., Vondrasek, R., Bailey, T., Callahan, L., Clark, A. M., Collon, P., and Kashiv, Y.

Subjects
NEUTRON capture, NUCLEAR reactions, NUCLEAR astrophysics, NUCLEOSYNTHESIS, DEUTERIUM
Abstract

The thermodynamical conditions and the neutron density produced in a laser-induced implosion of a deuterium-tritium (DT) filled capsule at the National Ignition Facility (NIF) are the closest laboratory analog of stellar conditions. We plan to investigate neutron-induced reactions on 40Ar, namely the 40Ar(n, 2n)39Ar(t1/2 =268 y), the 40Ar(n, γ)41Ar(110 min) and the potential rapid two-neutron capture reaction 40Ar(2n, γ)42Ar(33 y) in an Ar-loaded DT capsule. The chemical inertness of noble gas Ar enables reliable collection of the reaction products. [ABSTRACT FROM AUTHOR]

Published
2023
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14. Measuring neutron capture rates on ILL-produced unstable isotopes (147Pm, 171Tm and 204Tl, and plans for 79Se and 163Ho) for nucleosynthesis studies

Author

Lerendegui-Marco J., Guerrero C., Domingo-Pardo C., Casanovas A., Dressler R., Halfon S., Heinitz S., Kivel N., Köster U., Paul M., Schumann D., and Tessler M.

Subjects
Physics, QC1-999
Abstract

Neutron capture cross sections are among the main inputs for nucleosynthesis network calculations. Although well known for the majority of the stable isotopes, this quantity is still unknown for most of the unstable isotopes of interest. A recent collaboration between ILL, PSI, U. Sevilla and IFIC aims at producing the isotopes of interest at ILL, preparing suitable targets at PSI, and measuring their capture cross sections at facilities such as n_TOF/CERN, LiLiT and the Budapest Research Reactor (BRR). This work is focused on the description of the different beams and techniques and shows some highlights of the preliminary results of the capture measurements on 171Tm, 147Pm and 204Tl, along with the future plans for 79Se and 163Ho.

Published
2018
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20. Time-of-flight and activation experiments on 147Pm and 171Tm for astrophysics

Author

Guerrero C., Lerendegui-Marco J., Domingo-Pardo C., Casanovas A., Dressler R., Halfon S., Heinitz S., Kivel N., Köster U., Paul M., Quesada-Molina J.M., Schumann D., Tarifeño-Saldivia A., Tessler M., Weissman L., Aberle O., Andrzejewski J., Audouin L., Bacak M., Balibrea J., Barbagallo M., Becvar F., Berthoumieux E., Billowes J., Bosnar D., Brown A., Caamaño M., Calviño F., Calviani M., Cano-Ott D., Cardella R., Cerutti F., Chen Y.H., Chiaveri E., Colonna N., Cortés G., Cortés-Giraldo M.A., Cosentino L., Damone L.A., Diakaki M., Dupont E., Durán I., Fernández-Domínguez B., Ferrari A., Ferreira P., Finocchiaro P., Göbel K., García A.R., Gawlik A., Gilardoni S., Glodariu T., Gonçalves I.F., González E., Griesmayer E., Gunsing F., Harada H., Heyse J., Jenkins D.G., Jericha E., Käppeler F., Kadi Y., Kalamara A., Kavrigin P., Kimura A., Kokkoris M., Krticka M., Kurtulgil D., Leal-Cidoncha E., Lederer C., Leeb H., Meo S. Lo, Lonsdale S.J., Macina D., Marganiec J., Martínez T., Masi A., Massimi C., Mastinu P., Mastromarco M., Maugeri E.A., Mazzone A., Mendoza E., Mengoni A., Milazzo P.M., Mingrone F., Musumarra A., Negret A., Nolte R., Oprea A., Patronis N., Pavlik A., Perkowski J., Porras I., Praena J., Radeck D., Rauscher T., Reifarth R., Rout P.C., Rubbia C., Ryan J.A., Sabaté-Gilarte M., Saxena A., Schillebeeckx P., Smith A.G., Sosnin N.V., Stamatopoulos A., Tagliente G., Tain J.L., Tassan-Got L., Tsinganis A., Valenta S., Vannini G., Variale V., Vaz P., Ventura A., Vlachoudis V., Vlastou R., Wallner A., Warren S., Weiss C., Woods P.J., Wright T., and Žugec P.

Subjects
Physics, QC1-999
Abstract

The neutron capture cross section of several key unstable isotopes acting as branching points in the s-process are crucial for stellar nucleosynthesis studies, but they are very challenging to measure due to the difficult production of sufficient sample material, the high activity of the resulting samples, and the actual (n,γ) measurement, for which high neutron fluxes and effective background rejection capabilities are required. As part of a new program to measure some of these important branching points, radioactive targets of 147Pm and 171Tm have been produced by irradiation of stable isotopes at the ILL high flux reactor. Neutron capture on 146Nd and 170Er at the reactor was followed by beta decay and the resulting matrix was purified via radiochemical separation at PSI. The radioactive targets have been used for time-of-flight measurements at the CERN n_TOF facility using the 19 and 185 m beam lines during 2014 and 2015. The capture cascades were detected using a set of four C6D6 scintillators, allowing to observe the associated neutron capture resonances. The results presented in this work are the first ever determination of the resonance capture cross section of 147Pm and 171Tm. Activation experiments on the same 147Pm and 171Tm targets with a high-intensity 30 keV quasi-Maxwellian flux of neutrons will be performed using the SARAF accelerator and the Liquid-Lithium Target (LiLiT) in order to extract the corresponding Maxwellian Average Cross Section (MACS). The status of these experiments and preliminary results will be presented and discussed as well.

Published
2017
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21. Stellar s -process neutron capture cross sections on 78,80,84,86Kr determined via activation, atom trap trace analysis, and decay counting

Author

Tessler, M., Zappala, J., Cristallo, S., Roberti, L., Paul, M., Halfon, S., Heftrich, T., Jiang, W., Kijel, D., Kreisel, A., Limongi, M., Z. -T., Lu, Muller, P., Purtschert, R., Reifarth, R., Shor, A., Veltum, D., Vescovi, D., Weigand, M., Weissman, L., ITA, USA, DEU, TWN, JPN, ISR, and CHE

Subjects
Radiative capture, Hydrostatic stellar nucleosynthesis, Nuclear astrophysics, Radiative capture, Nuclear astrophysics, Hydrostatic stellar nucleosynthesis
Abstract

We present a detailed account of neutron capture experiments of astrophysical relevance on 78,80,84,86Kr (n ,γ ) reactions at the border between weak and main s process. The experiments were performed with quasi-Maxwellian neutrons from the Liquid-Lithium Target (LiLiT) and the mA-proton beam at 1.93 MeV (2-3 kW) of the Soreq Applied Research Accelerator Facility (SARAF). The setup yields high-intensity ≈40 keV quasi-Maxwellian neutrons (3-5 ×1010 n /s) closely reproducing the conditions of s -process stellar nucleosynthesis. A sample of 100 mg of atmospheric, pre-nuclear-age Kr gas contained in a Ti spherical shell was activated in the LiLiT neutron field. The abundances of long-lived Kr isotopes (81,85 gKr) were measured by atom counting via atom trap trace analysis (ATTA) at Argonne National Laboratory and low-level counting (LLC) at University of Bern. This work is the first measurement of a nuclear cross section using atom counting via ATTA. The activities of short-lived Kr isotopes (79,85 m,87Kr) were measured by γ -decay counting with a high-purity germanium detector. Maxwellian-averaged cross sections for s -process thermal energies are extracted. By comparison to reference values, our nucleosynthesis network calculations show that the experimental cross sections have a strong impact on calculated abundances of krypton and neighboring nuclides, in some cases improving agreement between theory and observations.

Published
2021

24. Neutron Capture on the s -Process Branching Point Tm 171 via Time-of-Flight and Activation

Author

Guerrero, C., Lerendegui-Marco, J., Paul, M., Tessler, M., Heinitz, S., Domingo-Pardo, C., CRISTALLO, Sergio, ITA, GBR, FRA, DEU, ESP, AUT, BEL, HRV, GRC, and CZE

Abstract

The neutron capture cross sections of several unstable nuclides acting as branching points in the s process are crucial for stellar nucleosynthesis studies. The unstable Tm 171 (t1 /2=1.92 yr ) is part of the branching around mass A ∼170 but its neutron capture cross section as a function of the neutron energy is not known to date. In this work, following the production for the first time of more than 5 mg of Tm 171 at the high-flux reactor Institut Laue-Langevin in France, a sample was produced at the Paul Scherrer Institute in Switzerland. Two complementary experiments were carried out at the neutron time-of-flight facility (n _TOF ) at CERN in Switzerland and at the SARAF liquid lithium target facility at Soreq Nuclear Research Center in Israel by time of flight and activation, respectively. The result of the time-of-flight experiment consists of the first ever set of resonance parameters and the corresponding average resonance parameters, allowing us to make an estimation of the Maxwellian-averaged cross sections (MACS) by extrapolation. The activation measurement provides a direct and more precise measurement of the MACS at 30 keV: 384(40) mb, with which the estimation from the n _TOF data agree at the limit of 1 standard deviation. This value is 2.6 times lower than the JEFF-3.3 and ENDF/B-VIII evaluations, 25% lower than that of the Bao et al. compilation, and 1.6 times larger than the value recommended in the KADoNiS (v1) database, based on the only previous experiment. Our result affects the nucleosynthesis at the A ∼170 branching, namely, the Yb 171 abundance increases in the material lost by asymptotic giant branch stars, providing a better match to the available pre-solar SiC grain measurements compared to the calculations based on the current JEFF-3.3 model-based evaluation.

Published
2020

26. Stellar 78,80,84,86Kr(n,γ) Reactions Studied by Activation at SARAF-LiLiT, Atom Trap Trace Analysis and Decay Counting

Author

Tessler, M., primary, Paul, M., additional, Weissman, L., additional, Zappala, J., additional, Baggenstos, D., additional, Halfon, S., additional, Heftrich, T., additional, Jiang, W., additional, Kreisel, A., additional, Lu, Z., additional, Mueller, P., additional, Purtschert, R., additional, Reifarth, R., additional, Shor, A., additional, Veltum, D., additional, and Weigand, M., additional

Published
2020
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27. The -process in the Nd-Pm-Sm region: Neutron activation of Pm

Author

Guerrero, C., Tessler, M., Paul, M., Lerendegui-Marco, J., Heinitz, S., Maugeri, E.A., Domingo-Pardo, C., Dressler, R., Halfon, S., Kivel, N., Köster, U., Palchan-Hazan, T., Quesada, J.M., Schumann, D., and Weissman, L.

Abstract

The Nd-Pm-Sm branching is of interest for the study of the s-process, related to the production of heavy elements in stars. As $^{148}$Sm and $^{150}$Sm are s-only isotopes, the understanding of the branching allows constraining the s-process neutron density. In this context the key physics input needed is the cross section of the three unstable nuclides in the region: $^{147}$Nd (10.98 d half-life), $^{147}$Pm (2.62 yr) and $^{148}$Pm (5.37 d). This paper reports on the activation measurement of $^{147}$Pm, the longest-lived of the three nuclides. The cross section measurement has been carried out by activation at the SARAF LiLiT facility using a 56(2) μg target. Compared to the single previous measurement of $^{147}$Pm, the measurement presented herein benefits from a target 2000 times more massive. The resulting Maxwellian Averaged Cross Section (MACS) to the ground and metastable states in $^{148}$Pm are 469(50) mb and 357(27) mb. These values are 41% higher (to the ground state) and 15% lower (to the metastable state) than the values reported so far, leading however to a total cross section of 826(107) mb consistent within uncertainties with the previous result and hence leaving unchanged the previous calculation of the s-process neutron density.

Published
2019

28. Stellar 30-keV neutron capture in 94, 96Zr and the Zr90(γ,n)Zr89 photonuclear reaction with a high-power liquid-lithium target

Author

Tessler, M., Paul, M., Arenshtam, A., Feinberg, G., Friedman, M., Halfon, S., Kijel, D., Weissman, L., Aviv, O., Berkovits, D., Eisen, Y., Eliyahu, I., Haquin, G., Kreisel, A., Mardor, I., Shimel, G., Shor, A., Silverman, I., and Yungrais, Z.

Subjects
High-intensity neutron source, Maxwellian Averaged Cross Section (MACS), Zr90(γ,n), Li7(p,n), Zr94,96(n,γ), lcsh:Physics, lcsh:QC1-999
Abstract

A high-power Liquid-Lithium Target (LiLiT) was used for the first time for neutron production via the thick-target Li7(p,n)Be7 reaction and quantitative determination of neutron capture cross sections. Bombarded with a 1–2 mA proton beam at 1.92 MeV from the Soreq Applied Research Accelerator Facility (SARAF), the setup yields a 30-keV quasi-Maxwellian neutron spectrum with an intensity of 3– 5×1010 n/s , more than one order of magnitude larger than present near-threshold Li7(p,n) neutron sources. The setup was used here to determine the 30-keV Maxwellian averaged cross section (MACS) of 94 Zr and 96 Zr as 28.0±0.6 mb and 12.4±0.5 mb respectively, based on activation measurements. The precision of the cross section determinations results both from the high neutron yield and from detailed simulations of the entire experimental setup. We plan to extend our experimental studies to low-abundance and radioactive targets. In addition, we show here that the setup yields intense high-energy (17.6 and 14.6 MeV) prompt capture γ rays from the Li7(p,γ)Be8 reaction with yields of ∼3×108γs−1mA−1 and ∼4×108γs−1mA−1 , respectively, evidenced by the Zr90(γ,n)Zr89 photonuclear reaction.

Published
2015

30. Time-of-flight and activation experiments on $^{147}$Pm and $^{171}$Tm for astrophysics

Author

n_TOF Collaboration, Guerrero, C., Lerendegui-Marco, J., Domingo-Pardo, C., Casanovas, A., Dressler, R., Halfon, S., Heinitz, S., Kivel, N., Köster, U., Paul, M., Quesada-Molina, J. M., Schumann, D., Tarifeño-Saldivia, A., Tessler, M., Weissman, L., Aberle, O., Andrzejewski, J., Audouin, L., Bacak, M., Balibrea, J., Barbagallo, M., Becvar, F., Berthoumieux, E., Billowes, J., Bosnar, D., Brown, A., Caamaño, M., Calviño, F., Calviani, M., Cano-Ott, D., Cardella, R., Cerutti, F., Chen, Y. H., Chiaveri, E., Colonna, N., Cortés, G., Cortés-Giraldo, M. A., Cosentino, L., Damone, L. A., Diakaki, M., Dupont, E., Durán, I., Fernández-Domínguez, B., Ferrari, A., Ferreira, P., Finocchiaro, P., Göbel, K., García, A. R., Gawlik, A., Gilardoni, S., Glodariu, T., Gonçalves, I. F., González, E., Griesmayer, E., Gunsing, F., Harada, H., Heyse, J., Jenkins, D. G., Jericha, E., Käppeler, F., Kadi, Y., Kalamara, A., Kavrigin, P., Kimura, A., Kokkoris, M., Krticka, M., Kurtulgil, D., Leal-Cidoncha, E., Lederer, C., Leeb, H., Meo, S. L., Lonsdale, S. J., Macina, D., Marganiec, J., Martínez, T., Masi, A., Massimi, C., Mastinu, P., Mastromarco, M., Maugeri, E. A., Mazzone, A., Mendoza, E., Mengoni, A., Milazzo, P. M., Mingrone, F., Musumarra, A., Negret, A., Nolte, R., Oprea, A., Patronis, N., Pavlik, A., Perkowski, J., Porras, I., Praena, J., Radeck, D., Rauscher, T., Reifarth, R., Rout, P. C., Rubbia, C., Ryan, J. A., Sabaté-Gilarte, M., Saxena, A., Schillebeeckx, P., Smith, A. G., Sosnin, N. V., Stamatopoulos, A., Tagliente, G., Tain, J. L., Tassan-Got, L., Tsinganis, A., Valenta, S., Vannini, G., Variale, V., Vaz, P., Ventura, A., Vlachoudis, V., Vlastou, R., Wallner, A., Warren, S., Weiss, C., Woods, P. J., Wright, T., and Ugec, P.

Subjects
Physics, ddc:530
Published
2017

31. Measuring neutron capture rates on ILL-produced unstable isotopes (147Pm, 171Tm and 204Tl, and plans for 79Se and 163Ho) for nucleosynthesis studies.

Author

Köster, U., Lerendegui-Marco, J., Guerrero, C., Domingo-Pardo, C., Casanovas, A., Dressler, R., Halfon, S., Heinitz, S., Kivel, N., Paul, M., Schumann, D., and Tessler, M.

Subjects
NEUTRON capture, STABLE isotopes, NUCLEOSYNTHESIS, NUCLEAR reactors, NUCLEAR cross sections
Abstract

Neutron capture cross sections are among the main inputs for nucleosynthesis network calculations. Although well known for the majority of the stable isotopes, this quantity is still unknown for most of the unstable isotopes of interest. A recent collaboration between ILL, PSI, U. Sevilla and IFIC aims at producing the isotopes of interest at ILL, preparing suitable targets at PSI, and measuring their capture cross sections at facilities such as n_TOF/CERN, LiLiT and the Budapest Research Reactor (BRR). This work is focused on the description of the different beams and techniques and shows some highlights of the preliminary results of the capture measurements on 171Tm, 147Pm and 204Tl, along with the future plans for 79Se and 163Ho. [ABSTRACT FROM AUTHOR]

Published
2018

32. Determination of the Maxwellian-averaged cross section of 35Cl(n,gamma)

Author

Pavetich, S., Akhmadaliev, S., Dillmann, I., Fifield, K., Halfon, S., Heftrich, T., Käppeler, F., Lederer, C., Martschini, M., Merchel, S., Paul, M., Reifarth, R., Rugel, G., Steier, P., Tessler, M., Tims, S., Wallner, A., Weigand, M., Weissman, L., Pavetich, S., Akhmadaliev, S., Dillmann, I., Fifield, K., Halfon, S., Heftrich, T., Käppeler, F., Lederer, C., Martschini, M., Merchel, S., Paul, M., Reifarth, R., Rugel, G., Steier, P., Tessler, M., Tims, S., Wallner, A., Weigand, M., and Weissman, L.

Abstract

In stellar environments neutron capture reactions produce 99% of all elements heavier than iron. In the slow neutron capture process (s-process) lighter isotopes, especially those with high abundances and large neutron capture cross sections, act as “neutron poisons” by reducing the number of available neutrons and hence, decreasing the production of the heavier nuclei. 35Cl, which is produced in advanced burning phases of stars, contributes to the poisoning effect. Accordingly, its Maxwellian-averaged cross section (MACS) is of significant astrophysical interest. A combination of activation technique and accelerator mass spectrometry (AMS) was used for the determination of the MACS of 35Cl(n,gamma)36Cl. NaCl pellets were irradiated at KIT and SARAF-LiLiT (Soreq Applied Research Accelerator Facility-Liquid-Lithium Target) with a quasi-Maxwellian neutron energy distribution of 25 keV. The neutron fluence was monitored by gold foils. AMS measurements at VERA (Vienna Environmental Research Accelerator), the DREAMS (DREsden AMS) facility and the ANU Heavy Ion Accelerator Facility quantified the 36Cl/35Cl ratio of the samples. The product of the neutron fluence and the isotopic ratio gives the spectrum-averaged cross section of the reaction. By normalizing this value to a real Maxwellian spectrum a new value for the 25 keV MACS of (9.5±0.4) mb for the reaction 35Cl(n,gamma)36Cl was obtained. This is ~16% lower than the previously determined value in Guber et al [1]. [1] K. H. Guber et al., Phys. Rev. C 65, 058801 (2002).

Published
2016

35. Time-of-flight and activation experiments on 147Pm and 171Tm for astrophysics.

Author

Guerrero, C., Lerendegui-Marco, J., Domingo-Pardo, C., Casanovas, A., Dressler, R., Halfon, S., Heinitz, S., Kivel, N., Köster, U., Paul, M., Quesada-Molina, J. M., Schumann, D., Tarifeño-Saldivia, A., Tessler, M., Weissman, L., Aberle, O., Andrzejewski, J., Audouin, L., Bacak, M., and Balibrea, J.

Subjects
THULIUM isotopes, PROMETHIUM isotopes, NUCLEAR astrophysics, TIME-of-flight spectrometry, NEUTRON capture, NUCLEOSYNTHESIS
Abstract

The neutron capture cross section of several key unstable isotopes acting as branching points in the s-process are crucial for stellar nucleosynthesis studies, but they are very challenging to measure due to the difficult production of sufficient sample material, the high activity of the resulting samples, and the actual (n,γ) measurement, for which high neutron fluxes and effective background rejection capabilities are required. As part of a new program to measure some of these important branching points, radioactive targets of 147Pm and 171Tm have been produced by irradiation of stable isotopes at the ILL high flux reactor. Neutron capture on 146Nd and 170Er at the reactor was followed by beta decay and the resulting matrix was purified via radiochemical separation at PSI. The radioactive targets have been used for time-of-flight measurements at the CERN n TOF facility using the 19 and 185m beam lines during 2014 and 2015. The capture cascades were detected using a set of four C6D6 scintillators, allowing to observe the associated neutron capture resonances. The results presented in this work are the first ever determination of the resonance capture cross section of 147Pm and 171Tm. Activation experiments on the same 147Pm and 171Tm targets with a high-intensity 30 keV quasi-Maxwellian flux of neutrons will be performed using the SARAF accelerator and the Liquid-Lithium Target (LiLiT) in order to extract the corresponding Maxwellian Average Cross Section (MACS). The status of these experiments and preliminary results will be presented and discussed as well. [ABSTRACT FROM AUTHOR]

Published
2017
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36. Stellar 30-keV neutron capture in 94, 96 Zr and theZr90(γ,n)Zr89photonuclear reaction with a high-power liquid-lithium target

Author

Tessler, M., primary, Paul, M., additional, Arenshtam, A., additional, Feinberg, G., additional, Friedman, M., additional, Halfon, S., additional, Kijel, D., additional, Weissman, L., additional, Aviv, O., additional, Berkovits, D., additional, Eisen, Y., additional, Eliyahu, I., additional, Haquin, G., additional, Kreisel, A., additional, Mardor, I., additional, Shimel, G., additional, Shor, A., additional, Silverman, I., additional, and Yungrais, Z., additional

Published
2015
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37. Environmental and anthropogenic indicators for coastal risk assessment at Massaguaçú Beach (SP) Brazil

Author

Paulo Sousa, Siegle, E., and Tessler, M. G.

Subjects
Occupation, Urban Plannin, Planejamento urbano, Erosão Costal, Coastal Erosion, Ocupação
Abstract

As a widespread trend, coastal erosion is occurring on many countries around the world. In general, such process is translated in environmental and socioeconomic damages in many coastal cities. The aim of this work is to use environmental and anthropogenic indicators to manage natural resources and subsidize regional planning. The study site is Massaguaçú Beach in Caraguatatuba, Northern Coast of São Paulo State, Brazil. The beach has been divided into three sectors and classified according to its risk in low, moderate and high. The indicators are beach profile, shoreline position, dune field, offshore settings, presence of rivers and/or inlets, terrain elevation, vegetation, coastal engineering structures, occupation rate and soil permeability. General information on these variables were extracted through remote sensing and geoprocessing techniques. The three beach sectors present different alongshore length, but a constant cross-shore distance of 500 m landwards from the water line. Sector 1, the southern part of the beach, is marked by the presence of the Massaguaçú River; sector 2, central part, concentrates the urban settlement; and sector 3, in the north, comprehends the Bracuí River and the landforms restricts the occupation in this area. Sectors 1 and 3 were classified as being of moderate risk, while sector 2 as being of high risk. Although the occupation rate is not too high, it has limited the beach profile and sediment budget. Any interventions in Massaguaçú should consider the sediment budget behavior and erosive trends.

Published
2011

38. Statement by scholars of Iran, the Middle East, and others protesting the detention of Dr. Haleh Esfandiari by the Iranian government

Author

Abrahamian, E, Afary, J, Afkhami, M, Afshari, R, Ashraf, A, Badinter, R, Banuazizi, A, Brand, LA, Brown, LC, Buruma, I, Chomsky, N, Cole, JR, Danner, M, Davis, NZ, Dworkin, R, Esposito, JL, Fukuyama, F, Garton Ash, T, Gasiorowski, M, Ghanoonparvar, MR, Habermas, J, Haghighatjoo, F, Hekmat, H, Hoffmann, S, Judt, T, Kar, M, Karimi-Hakkak, A, Kazemi, F, Keddie, N, Kueng, H, Lewis, A, Lifton, RJ, Lilla, M, Lockman, Z, MacMillan, M, Mayer, AE, Mazowiecki, T, Michnik, A, Mottahedeh, RP, Nafisi, A, Nafisi, R, Neier, A, Norton, AR, Power, S, Quandt, WB, Rahimieh, N, Ramadan, T, Rogan, E, Rubin, E, Shlaim, A, Takeyh, R, Tavakoli-Targhi, M, Taylor, C, Tessler, M, Toensing, C, Tohidi, N, Van Evera, S, Walt, SM, Waterbury, J, Weschler, L, Young-Bruehl, E, Yousef, S, and Zonis, M

Published
2007

42. Tunisia's new beginning.

Author

Tessler, M.

Subjects
*POLITICAL science, TUNISIAN politics & government
Abstract

Studies the key factors that are influencing Tunisia's political future. Historical overview of independent Tunisia; Rise to power of Zine el-Abedine Ben Ali as President; Emerging political system under Ben Ali; Opposition parties; Future challenges.

Published
1990

43. Neutron Capture on the s -Process Branching Point Tm 171 via Time-of-Flight and Activation

Author

Guerrero, C., Lerendegui-Marco, J., Paul, M., Tessler, M., Heinitz, S., Domingo-Pardo, C., Cristallo, S., Dressler, R., Halfon, S., Kivel, N., Köster, U., Maugeri, E.a., Palchan-Hazan, T., Quesada, J.M., Rochman, D., Schumann, D., Weissman, L., Aberle, O., Amaducci, S., Andrzejewski, J., Audouin, L., Bécares, V., Bacak, M., Balibrea, J., Barak, A., Barbagallo, M., Barros, S., Bečvář, F., Beinrucker, C., Berkovits, D., Berthoumieux, E., Billowes, J., Bosnar, D., Brugger, M., Buzaglo, Y., Caamaño, M., Calviño, F., Calviani, M., Cano-Ott, D., Cardella, R., Casanovas, A., Castelluccio, D.M., Cerutti, F., Chen, Y.H., Chiaveri, E., Colonna, N., Cortés, G., Cortés-Giraldo, M.A., Cosentino, L., Dafna, H., Damone, A., Diakaki, M., Dietz, M., Dupont, E., Durán, I., Eisen, Y., Fernández-Domínguez, B., Ferrari, A., Ferreira, P., Finocchiaro, P., Furman, V., Göbel, K., García, A.R., Gawlik, A., Glodariu, T., Gonçalves, I.F., González-Romero, E., Goverdovski, A., Griesmayer, E., Gunsing, F., Harada, H., Heftrich, T., Heyse, J., Hirsh, T., Jenkins, D.G., Jericha, E., Käppeler, F., Kadi, Y., Kaizer, B., Katabuchi, T., Kavrigin, P., Ketlerov, V., Khryachkov, V., Kijel, D., Kimura, A., Kokkoris, M., Kriesel, A., Krtička, M., Leal-Cidoncha, E., Lederer-Woods, C., Leeb, H., Lo Meo, S., Lonsdale, S.J., Losito, R., Macina, D., Manna, A., Marganiec, J., Martínez, T., Massimi, C., Mastinu, P., Mastromarco, M., Matteucci, F., Mendoza, E., Mengoni, A., Milazzo, P.M., Millán-Callado, M.A., Mingrone, F., Mirea, M., Montesano, S., Musumarra, A., Nolte, R., Oprea, A., Patronis, N., Pavlik, A., Perkowski, J., Piersanti, L., Porras, I., Praena, J., Rajeev, K., Rauscher, T., Reifarth, R., Rodríguez-González, T., Rout, P.C., Rubbia, C., Ryan, J.A., Sabaté-Gilarte, M., Saxena, A., Schillebeeckx, P., Schmidt, S., Shor, A., Sedyshev, P., Smith, A.G., Stamatopoulos, A., Tagliente, G., Tain, J.L., Tarifeño-Saldivia, A., Tassan-Got, L., Tsinganis, A., Valenta, S., Vannini, G., Variale, V., Vaz, P., Ventura, A., Vlachoudis, V., Vlastou, R., Wallner, A., Warren, S., Weigand, M., Weiss, C., Wolf, C., Woods, P.J., Wright, T., Žugec, P., Institut Laue-Langevin (ILL), Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, n_TOF, Guerrero C., Lerendegui-Marco J., Paul M., Tessler M., Heinitz S., Domingo-Pardo C., Cristallo S., Dressler R., Halfon S., Kivel N., Koster U., Maugeri E.A., Palchan-Hazan T., Quesada J.M., Rochman D., Schumann D., Weissman L., Aberle O., Amaducci S., Andrzejewski J., Audouin L., Becares V., Bacak M., Balibrea J., Barak A., Barbagallo M., Barros S., Becvar F., Beinrucker C., Berkovits D., Berthoumieux E., Billowes J., Bosnar D., Brugger M., Buzaglo Y., Caamano M., Calvino F., Calviani M., Cano-Ott D., Cardella R., Casanovas A., Castelluccio D.M., Cerutti F., Chen Y.H., Chiaveri E., Colonna N., Cortes G., Cortes-Giraldo M.A., Cosentino L., Dafna H., Damone A., Diakaki M., Dietz M., Dupont E., Duran I., Eisen Y., Fernandez-Dominguez B., Ferrari A., Ferreira P., Finocchiaro P., Furman V., Gobel K., Garcia A.R., Gawlik A., Glodariu T., Goncalves I.F., Gonzalez-Romero E., Goverdovski A., Griesmayer E., Gunsing F., Harada H., Heftrich T., Heyse J., Hirsh T., Jenkins D.G., Jericha E., Kappeler F., Kadi Y., Kaizer B., Katabuchi T., Kavrigin P., Ketlerov V., Khryachkov V., Kijel D., Kimura A., Kokkoris M., Kriesel A., Krticka M., Leal-Cidoncha E., Lederer-Woods C., Leeb H., Lo Meo S., Lonsdale S.J., Losito R., MacIna D., Manna A., Marganiec J., Martinez T., Massimi C., Mastinu P., Mastromarco M., Matteucci F., Mendoza E., Mengoni A., Milazzo P.M., Millan-Callado M.A., Mingrone F., Mirea M., Montesano S., Musumarra A., Nolte R., Oprea A., Patronis N., Pavlik A., Perkowski J., Piersanti L., Porras I., Praena J., Rajeev K., Rauscher T., Reifarth R., Rodriguez-Gonzalez T., Rout P.C., Rubbia C., Ryan J.A., Sabate-Gilarte M., Saxena A., Schillebeeckx P., Schmidt S., Shor A., Sedyshev P., Smith A.G., Stamatopoulos A., Tagliente G., Tain J.L., Tarifeno-Saldivia A., Tassan-Got L., Tsinganis A., Valenta S., Vannini G., Variale V., Vaz P., Ventura A., Vlachoudis V., Vlastou R., Wallner A., Warren S., Weigand M., Weiss C., Wolf C., Woods P.J., Wright T., Zugec P., Guerrero, C., Lerendegui-Marco, J., Paul, M., Tessler, M., Heinitz, S., Domingo-Pardo, C., Cristallo, S., Dressler, R., Halfon, S., Kivel, N., Koster, U., Maugeri, E. A., Palchan-Hazan, T., Quesada, J. M., Rochman, D., Schumann, D., Weissman, L., Aberle, O., Amaducci, S., Andrzejewski, J., Audouin, L., Becares, V., Bacak, M., Balibrea, J., Barak, A., Barbagallo, M., Barros, S., Becvar, F., Beinrucker, C., Berkovits, D., Berthoumieux, E., Billowes, J., Bosnar, D., Brugger, M., Buzaglo, Y., Caamano, M., Calvino, F., Calviani, M., Cano-Ott, D., Cardella, R., Casanovas, A., Castelluccio, D. M., Cerutti, F., Chen, Y. H., Chiaveri, E., Colonna, N., Cortes, G., Cortes-Giraldo, M. A., Cosentino, L., Dafna, H., Damone, A., Diakaki, M., Dietz, M., Dupont, E., Duran, I., Eisen, Y., Fernandez-Dominguez, B., Ferrari, A., Ferreira, P., Finocchiaro, P., Furman, V., Gobel, K., Garcia, A. R., Gawlik, A., Glodariu, T., Goncalves, I. F., Gonzalez-Romero, E., Goverdovski, A., Griesmayer, E., Gunsing, F., Harada, H., Heftrich, T., Heyse, J., Hirsh, T., Jenkins, D. G., Jericha, E., Kappeler, F., Kadi, Y., Kaizer, B., Katabuchi, T., Kavrigin, P., Ketlerov, V., Khryachkov, V., Kijel, D., Kimura, A., Kokkoris, M., Kriesel, A., Krticka, M., Leal-Cidoncha, E., Lederer-Woods, C., Leeb, H., Lo Meo, S., Lonsdale, S. J., Losito, R., Macina, D., Manna, A., Marganiec, J., Martinez, T., Massimi, C., Mastinu, P., Mastromarco, M., Matteucci, F., Mendoza, E., Mengoni, A., Milazzo, P. M., Millan-Callado, M. A., Mingrone, F., Mirea, M., Montesano, S., Musumarra, A., Nolte, R., Oprea, A., Patronis, N., Pavlik, A., Perkowski, J., Piersanti, L., Porras, I., Praena, J., Rajeev, K., Rauscher, T., Reifarth, R., Rodriguez-Gonzalez, T., Rout, P. C., Rubbia, C., Ryan, J. A., Sabate-Gilarte, M., Saxena, A., Schillebeeckx, P., Schmidt, S., Shor, A., Sedyshev, P., Smith, A. G., Stamatopoulos, A., Tagliente, G., Tain, J. L., Tarifeno-Saldivia, A., Tassan-Got, L., Tsinganis, A., Valenta, S., Vannini, G., Variale, V., Vaz, P., Ventura, A., Vlachoudis, V., Vlastou, R., Wallner, A., Warren, S., Weigand, M., Weiss, C., Wolf, C., Woods, P. J., Wright, T., Zugec, P., ILL, and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)

Subjects
PRIRODNE ZNANOSTI. Fizika, Physics, ddc:530, s process nucleosynthesis, n_TOF, neutron physics, 171Tm, Nuclear Physics - Experiment, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], NATURAL SCIENCES. Physics, Nuclear Physics
Abstract

International audience; The neutron capture cross sections of several unstable nuclides acting as branching points in the s process are crucial for stellar nucleosynthesis studies. The unstable Tm171 (t1/2=1.92 yr) is part of the branching around mass A∼170 but its neutron capture cross section as a function of the neutron energy is not known to date. In this work, following the production for the first time of more than 5 mg of Tm171 at the high-flux reactor Institut Laue-Langevin in France, a sample was produced at the Paul Scherrer Institute in Switzerland. Two complementary experiments were carried out at the neutron time-of-flight facility (n_TOF) at CERN in Switzerland and at the SARAF liquid lithium target facility at Soreq Nuclear Research Center in Israel by time of flight and activation, respectively. The result of the time-of-flight experiment consists of the first ever set of resonance parameters and the corresponding average resonance parameters, allowing us to make an estimation of the Maxwellian-averaged cross sections (MACS) by extrapolation. The activation measurement provides a direct and more precise measurement of the MACS at 30 keV: 384(40) mb, with which the estimation from the n_TOF data agree at the limit of 1 standard deviation. This value is 2.6 times lower than the JEFF-3.3 and ENDF/B-VIII evaluations, 25% lower than that of the Bao et al. compilation, and 1.6 times larger than the value recommended in the KADoNiS (v1) database, based on the only previous experiment. Our result affects the nucleosynthesis at the A∼170 branching, namely, the Yb171 abundance increases in the material lost by asymptotic giant branch stars, providing a better match to the available pre-solar SiC grain measurements compared to the calculations based on the current JEFF-3.3 model-based evaluation.

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45. Time-of-flight and activation experiments on $^{147}$Pm and $^{171}$Tm for astrophysics

Author

Guerrero, C., Lerendegui-Marco, J., Domingo-Pardo, C., Casanovas, A., Dressler, R., Halfon, S., Heinitz, S., Kivel, N., Köster, U., Paul, M., Quesada-Molina, J. M., Schumann, D., Tarifeño-Saldivia, A., Tessler, M., Weissman, L., Aberle, O., Andrzejewski, J., Audouin, L., Bacak, M., Balibrea, J., Barbagallo, M., Becvar, F., Berthoumieux, E., Billowes, J., Bosnar, D., Brown, A., Caamaño, M., Calviño, F., Calviani, M., Cano-Ott, D., Cardella, R., Cerutti, F., Chen, Y. H., Chiaveri, E., Colonna, N., Cortés, G., Cortés-Giraldo, M. A., Cosentino, L., Damone, L. A., Diakaki, M., Dupont, E., Durán, I., Fernández-Domínguez, B., Ferrari, A., Ferreira, P., Finocchiaro, P., Göbel, K., García, A. R., Gawlik, A., Gilardoni, S., Glodariu, T., Gonçalves, I. F., González, E., Griesmayer, E., Gunsing, F., Harada, H., Heyse, J., Jenkins, D. G., Jericha, E., Käppeler, F., Kadi, Y., Kalamara, A., Kavrigin, P., Kimura, A., Kokkoris, M., Krticka, M., Kurtulgil, D., Leal-Cidoncha, E., Lederer, C., Leeb, H., Meo, S. L., Lonsdale, S. J., Macina, D., Marganiec, J., Martínez, T., Masi, A., Massimi, C., Mastinu, P., Mastromarco, M., Maugeri, E. A., Mazzone, A., Mendoza, E., Mengoni, A., Milazzo, P. M., Mingrone, F., Musumarra, A., Negret, A., Nolte, R., Oprea, A., Patronis, N., Pavlik, A., Perkowski, J., Porras, I., Praena, J., Radeck, D., Rauscher, T., Reifarth, R., Rout, P. C., Rubbia, C., Ryan, J. A., Sabaté-Gilarte, M., Saxena, A., Schillebeeckx, P., Smith, A. G., Sosnin, N. V., Stamatopoulos, A., Tagliente, G., Tain, J. L., Tassan-Got, L., Tsinganis, A., Valenta, S., Vannini, G., Variale, V., Vaz, P., Ventura, A., Vlachoudis, V., Vlastou, R., Wallner, A., Warren, S., Weiss, C., Woods, P. J., Wright, T., and Ugec, P.

Subjects
13. Climate action, 7. Clean energy

46. Neutron Capture on the s-Process Branching Point Tm 171 via Time-of-Flight and Activation

Author

Guerrero, C., Lerendegui-Marco, J., Paul, M., Tessler, M., Heinitz, S., Domingo-Pardo, C., Cristallo, S., Dressler, R., Halfon, S., Kivel, N., Köster, U., Maugeri, E. A., Palchan-Hazan, T., Quesada, J. M., Rochman, D., Schumann, D., Weissman, L., Aberle, O., Amaducci, S., Andrzejewski, J., Audouin, L., Bécares, V., Bacak, M., Balibrea, J., Barak, A., Barbagallo, M., Barros, S., Bečvář, F., Beinrucker, C., Berkovits, D., Berthoumieux, E., Billowes, J., Bosnar, D., Brugger, M., Buzaglo, Y., Caamaño, M., Calviño, F., Calviani, M., Cano-Ott, D., Cardella, R., Casanovas, A., Castelluccio, D. M., Cerutti, F., Chen, Y. H., Chiaveri, E., Colonna, N., Cortés, G., Cortés-Giraldo, M. A., Cosentino, L., Dafna, H., Damone, A., Diakaki, M., Dietz, M., Dupont, E., Durán, I., Eisen, Y., Fernández-Domínguez, B., Ferrari, A., Ferreira, P., Finocchiaro, P., Furman, V., Göbel, K., García, A. R., Gawlik, A., Glodariu, T., Gonçalves, I. F., González-Romero, E., Goverdovski, A., Griesmayer, E., Gunsing, F., Harada, H., Heftrich, T., Heyse, J., Hirsh, T., Jenkins, D. G., Jericha, E., Käppeler, F., Kadi, Y., Kaizer, B., Katabuchi, T., Kavrigin, P., Ketlerov, V., Khryachkov, V., Kijel, D., Kimura, A., Kokkoris, M., Kriesel, A., Krtička, M., Leal-Cidoncha, E., Lederer-Woods, C., Leeb, H., Lo Meo, S., Lonsdale, S. J., Losito, R., Macina, D., Manna, A., Marganiec, J., Martínez, T., Massimi, C., Mastinu, P., Mastromarco, M., Matteucci, F., Mendoza, E., Mengoni, A., Milazzo, P. M., Millán-Callado, M. A., Mingrone, F., Mirea, M., Montesano, S., Musumarra, A., Nolte, R., Oprea, A., Patronis, N., Pavlik, A., Perkowski, J., Piersanti, L., Porras, I., Praena, J., Rajeev, K., Rauscher, T., Reifarth, R., Rodríguez-González, T., Rout, P. C., Rubbia, C., Ryan, J. A., Sabaté-Gilarte, M., Saxena, A., Schillebeeckx, P., Schmidt, S., Shor, A., Sedyshev, P., Smith, A. G., Stamatopoulos, A., Tagliente, G., Tain, J. L., Tarifeño-Saldivia, A., Tassan-Got, L., Tsinganis, A., Valenta, S., Vannini, G., Variale, V., Vaz, P., Ventura, A., Vlachoudis, V., Vlastou, R., Wallner, A., Warren, S., Weigand, M., Weiss, C., Wolf, C., Woods, P. J., Wright, T., and Žugec, P.

Subjects
7. Clean energy
Abstract

The neutron capture cross sections of several unstable nuclides acting as branching points in the s process are crucial for stellar nucleosynthesis studies. The unstable $^{171}$Tm (t$_{1/2}$=1.92 yr) is part of the branching around mass A∼170 but its neutron capture cross section as a function of the neutron energy is not known to date. In this work, following the production for the first time of more than 5 mg of 171Tm at the high-flux reactor Institut Laue-Langevin in France, a sample was produced at the Paul Scherrer Institute in Switzerland. Two complementary experiments were carried out at the neutron time-of-flight facility (n_TOF) at CERN in Switzerland and at the SARAF liquid lithium target facility at Soreq Nuclear Research Center in Israel by time of flight and activation, respectively. The result of the time-of-flight experiment consists of the first ever set of resonance parameters and the corresponding average resonance parameters, allowing us to make an estimation of the Maxwellian-averaged cross sections (MACS) by extrapolation. The activation measurement provides a direct and more precise measurement of the MACS at 30 keV: 384(40) mb, with which the estimation from the n_TOF data agree at the limit of 1 standard deviation. This value is 2.6 times lower than the JEFF-3.3 and ENDF/B-VIII evaluations, 25% lower than that of the Bao et al. compilation, and 1.6 times larger than the value recommended in the KADoNiS (v1) database, based on the only previous experiment. Our result affects the nucleosynthesis at the A∼170 branching, namely, the $^{171}$Yb abundance increases in the material lost by asymptotic giant branch stars, providing a better match to the available pre-solar SiC grain measurements compared to the calculations based on the current JEFF-3.3 model-based evaluation.

48. Time-of-flight and activation experiments on 147Pm and 171Tm for astrophysics

Author

E. Leal-Cidoncha, P. M. Milazzo, M. Mastromarco, Rene Reifarth, O. Aberle, Simone Gilardoni, A. Gawlik, J. M. Quesada-Molina, Thomas Rauscher, D. Radeck, Michael Paul, J. Marganiec, R. Cardella, E. Berthoumieux, Javier Praena, S. Lo Meo, Leonid Weissman, M. Diakaki, M. Kokkoris, A. S. Brown, L. Tassan-Got, Anton Wallner, M. Caamaño, F. Cerutti, M. Tessler, L. Cosentino, J. Balibrea, S. Valenta, G. Cortes, A. Stamatopoulos, Deniz Kurtulgil, A. Oprea, N. V. Sosnin, J. Heyse, Marco Calviani, F. Mingrone, J. Andrzejewski, A. G. Smith, A. Kimura, D. Macina, Ariel Tarifeño-Saldivia, S. J. Lonsdale, J. L. Tain, A. Saxena, A. R. García, F. Gunsing, N. Patronis, Annamaria Mazzone, Petar Žugec, M. Bacak, I. Duran, P. Schillebeeckx, Philip Woods, S. Halfon, A. Casanovas, P. F. Mastinu, Ulli Köster, J. Lerendegui-Marco, P. Ferreira, Hideo Harada, Alfredo Ferrari, Mario Barbagallo, S. Warren, R. Dressler, Cristian Massimi, V. Variale, A. Kalamara, C. Weiss, D. Schumann, R. Vlastou, G. Tagliente, P. Kavrigin, I. F. Gonçalves, M. Sabaté-Gilarte, P. C. Rout, E. Mendoza, Y. H. Chen, Alexandru Negret, E. Griesmayer, R. Nolte, L. A. Damone, S. Heinitz, F. Becvar, A. Tsinganis, C. Lederer, A. Masi, E. Jericha, T. Glodariu, Paolo Finocchiaro, Damir Bosnar, Y. Kadi, F. Käppeler, J. A. Ryan, D. G. Jenkins, E. A. Maugeri, K. Göbel, N. Kivel, Ignacio Porras, Nicola Colonna, E. Dupont, G. Vannini, T. Wright, M. Krtička, E. González, M. A. Cortés-Giraldo, B. Fernández-Domínguez, T. Martinez, F. Calviño, L. Audouin, H. Leeb, Alberto Mengoni, J. Perkowski, Carlo Rubbia, V. Vlachoudis, Carlos Guerrero, P. Vaz, Alberto Ventura, A. Musumarra, E. Chiaveri, D. Cano-Ott, A. Pavlik, C. Domingo-Pardo, J. Billowes, Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. Institut de Tècniques Energètiques, Universitat Politècnica de Catalunya. ANT - Advanced Nuclear Technologies Research Group, Universitat Politècnica de Catalunya. NEMEN - Nanoenginyeria de materials aplicats a l'energia, Vannini, G., Mengoni, A., Lo Meo, S., Guerrero, C., Lerendegui-Marco, J., Domingo-Pardo, C., Casanovas, A., Dressler, R., Halfon, S., Heinitz, S., Kivel, N., Köster, U., Paul, M., Quesada-Molina, J.M., Schumann, D., Tarifeño-Saldivia, A., Tessler, M., Weissman, L., Aberle, O., Andrzejewski, J., Audouin, L., Bacak, M., Balibrea, J., Barbagallo, M., Becvar, F., Berthoumieux, E., Billowes, J., Bosnar, D., Brown, A., Caamaño, M., Calviño, F., Calviani, M., Cano-Ott, D., Cardella, R., Cerutti, F., Chen, Y.H., Chiaveri, E., Colonna, N., Cortés, G., Cortés-Giraldo, M.A., Cosentino, L., Damone, L.A., Diakaki, M., Dupont, E., Durán, I., Fernández-Domínguez, B., Ferrari, A., Ferreira, P., Finocchiaro, P., Göbel, K., García, A.R., Gawlik, A., Gilardoni, S., Glodariu, T., Gonçalves, I.F., González, E., Griesmayer, E., Gunsing, F., Harada, H., Heyse, J., Jenkins, D.G., Jericha, E., Käppeler, F., Kadi, Y., Kalamara, A., Kavrigin, P., Kimura, A., Kokkoris, M., Krticka, M., Kurtulgil, D., Leal-Cidoncha, E., Lederer, C., Leeb, H., Meo, S. Lo, Lonsdale, S.J., Macina, D., Marganiec, J., Martínez, T., Masi, A., Massimi, C., Mastinu, P., Mastromarco, M., Maugeri, E.A., Mazzone, A., Mendoza, E., Milazzo, P.M., Mingrone, F., Musumarra, A., Negret, A., Nolte, R., Oprea, A., Patronis, N., Pavlik, A., Perkowski, J., Porras, I., Praena, J., Radeck, D., Rauscher, T., Reifarth, R., Rout, P.C., Rubbia, C., Ryan, J.A., Sabaté-Gilarte, M., Saxena, A., Schillebeeckx, P., Smith, A.G., Sosnin, N.V., Stamatopoulos, A., Tagliente, G., Tain, J.L., Tassan-Got, L., Tsinganis, A., Valenta, S., Variale, V., Vaz, P., Ventura, A., Vlachoudis, V., Vlastou, R., Wallner, A., Warren, S., Weiss, C., Woods, P.J., Wright, T., Ugec, P., and Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear

Subjects
QC1-999, Neutron, Scintillator, 01 natural sciences, Nuclear physics, Physics and Astronomy (all), Stellar nucleosynthesis, Nucleosynthesis, 0103 physical sciences, Neutron cross section, 010306 general physics, Nuclear Experiment, Physics, Energies::Energia nuclear [Àrees temàtiques de la UPC], Neutrons, Isotope, Física [Àrees temàtiques de la UPC], 010308 nuclear & particles physics, Tof, Time of flight, Neutron capture, 13. Climate action, Nucleosíntesi
Abstract

The neutron capture cross section of several key unstable isotopes acting as branching points in the s-process are crucial for stellar nucleosynthesis studies, but they are very challenging to measure due to the difficult production of sufficient sample material, the high activity of the resulting samples, and the actual (n,γ ) measurement, for which high neutron fluxes and effective background rejection capabilities are required. As part of a new program to measure some of these important branching points, radioactive targets of 147Pm and 171Tm have been produced by irradiation of stable isotopes at the ILL high flux reactor. Neutron capture on 146Nd and 170Er at the reactor was followed by beta decay and the resulting matrix was purified via radiochemical separation at PSI. The radioactive targets have been used for time-of-flight measurements at the CERN n TOF facility using the 19 and 185m beam lines during 2014 and 2015. The capture cascades were detected using a set of four C6D6 scintillators, allowing to observe the associated neutron capture resonances. The results presented in this work are the first ever determination of the resonance capture cross section of 147Pm and 171Tm. Activation experiments on the same 147Pm and 171Tm targets with a high-intensity 30 keV quasi-Maxwellian flux of neutrons will be performed using the SARAF accelerator and the Liquid-Lithium Target (LiLiT) in order to extract the corresponding Maxwellian Average Cross Section (MACS). The status of these experiments and preliminary results will be presented and discussed as well., The authors acknowledge financial support by Spanish FPA2013-45083-P and FPA2014-53290-C2-2-P projects and the EC FP7 projects NeutAndalus (Grant No. 334315) and CHANDA (Grant No. 605203).

Published
2017

49. The Origin and Evolution of Antistasin-like Proteins in Leeches (Hirudinida, Clitellata).

Author

Iwama RE, Tessler M, Siddall ME, and Kvist S

Subjects
Animals, Anticoagulants chemistry, Factor Xa genetics, Hemostasis, Phylogeny, Salivary Proteins and Peptides genetics, Serine Proteinase Inhibitors genetics, Transcriptome, Annelida genetics, Annelida metabolism, Evolution, Molecular, Invertebrate Hormones genetics, Invertebrate Hormones metabolism, Leeches genetics
Abstract

Bloodfeeding is employed by many parasitic animals and requires specific innovations for efficient feeding. Some of these innovations are molecular features that are related to the inhibition of hemostasis. For example, bloodfeeding insects, bats, and leeches release proteins with anticoagulatory activity through their salivary secretions. The antistasin-like protein family, composed of serine protease inhibitors with one or more antistasin-like domains, is tightly linked to inhibition of hemostasis in leeches. However, this protein family has been recorded also in non-bloodfeeding invertebrates, such as cnidarians, mollusks, polychaetes, and oligochaetes. The present study aims to 1) root the antistasin-like gene tree and delimit the major orthologous groups, 2) identify potential independent origins of salivary proteins secreted by leeches, and 3) identify major changes in domain and/or motif structure within each orthologous group. Five clades containing leech antistasin-like proteins are distinguishable through rigorous phylogenetic analyses based on nine new transcriptomes and a diverse set of comparative data: the trypsin + leukocyte elastase inhibitors clade, the antistasin clade, the therostasin clade, and two additional, unnamed clades. The antistasin-like gene tree supports multiple origins of leech antistasin-like proteins due to the presence of both leech and non-leech sequences in one of the unnamed clades, but a single origin of factor Xa and trypsin + leukocyte elastase inhibitors. This is further supported by three sequence motifs that are exclusive to antistasins, the trypsin + leukocyte elastase inhibitor clade, and the therostasin clade, respectively. We discuss the implications of our findings for the evolution of this diverse family of leech anticoagulants., (© The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.)

Published
2021
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50. Spatial modeling could not differentiate early SARS-CoV-2 cases from the distribution of humans on the basis of climate in the United States.

Author

Harbert R, Cunningham SW, and Tessler M

Abstract

The SARS-CoV-2 coronavirus is wreaking havoc globally, yet, as a novel pathogen, knowledge of its biology is still emerging. Climate and seasonality influence the distributions of many diseases, and studies suggest at least some link between SARS-CoV-2 and weather. One such study, building species distribution models (SDMs), predicted SARS-CoV-2 risk may remain concentrated in the Northern Hemisphere, shifting northward in summer months. Others have highlighted issues with SARS-CoV-2 SDMs, notably: the primary niche of the virus is the host it infects, climate may be a weak distributional predictor, global prevalence data have issues, and the virus is not in population equilibrium. While these issues should be considered, we believe climate's relationship with SARS-CoV-2 is still worth exploring, as it may have some impact on the distribution of cases. To further examine if there is a link to climate, we build model projections with raw SARS-CoV-2 case data and population-scaled case data in the USA. The case data were from across March 2020, before large travel restrictions and public health policies were impacting cases across the country. We show that SDMs built from population-scaled case data cannot be distinguished from control models (built from raw human population data), while SDMs built on raw case data fail to predict the known distribution of cases in the U.S. from March. The population-scaled analyses indicate that climate did not play a central role in early U.S. viral distribution and that human population density was likely the primary driver. We do find slightly more population-scaled viral cases in cooler areas. Ultimately, the temporal and geographic constraints on this study mean that we cannot rule out climate as a partial driver of the SARS-CoV-2 distribution. Climate's role on SARS-CoV-2 should continue to be cautiously examined, but at this time we should assume that SARS-CoV-2 will continue to spread anywhere in the U.S. where governmental policy does not prevent spread., Competing Interests: The authors have no competing interests to declare., (© 2020 Harbert et al.)

Published
2020
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