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In Fig. 1c of this Article, the x-axis scale was inadvertently duplicated from Fig. 1b. The original Article has been corrected online.

The ratio of the nucleon F_{2} structure functions, F_{2}^{n}/F_{2}^{p}, is determined by the MARATHON experiment from measurements of deep inelastic scattering of electrons from ^{3}H and ^{3}He nuclei. The experiment was performed in the Hall A Facility of Jefferson Lab using two high-resolution spectrometers for electron detection, and a cryogenic target system which included a low-activity tritium cell. The data analysis used a novel technique exploiting the mirror symmetry of the two nuclei, which essentially eliminates many theoretical uncertainties in the extraction of the ratio. The results, which cover the Bjorken scaling variable range 0.19x0.83, represent a significant improvement compared to previous SLAC and Jefferson Lab measurements for the ratio. They are compared to recent theoretical calculations and empirical determinations of the F_{2}^{n}/F_{2}^{p} ratio.

When protons and neutrons (nucleons) are bound into atomic nuclei, they are close enough to feel significant attraction, or repulsion, from the strong, short-distance part of the nucleon-nucleon interaction. These strong interactions lead to hard collisions between nucleons, generating pairs of highly energetic nucleons referred to as short-range correlations (SRCs). SRCs are an important but relatively poorly understood part of nuclear structure

Inclusive electron scattering from nuclear targets has been measured to extract the nuclear dependence of the inelastic cross section in Hall C at the Thomas Jefferson National Accelerator facility. Results are presented for 2H, 3He, 4He, 9B, 12C, 63Cu and 197Au at an incident electron beam energy of 5.77 GeV for a range of momentum transfer from Q^2 = 2 to 7 (GeV/c)^2. These data improve the precision of the existing measurements of the EMC effect in the nuclear targets at large x, and allow for more detailed examinations of the A dependence of the EMC effect., Comment: 28 pages, 23 figures, archival paper for Jefferson Lab experiment E03-103

The fundamental building blocks of the proton, quarks and gluons, have been known for decades. However, we still have an incomplete theoretical and experimental understanding of how these particles and their dynamics give rise to the quantum bound state of the proton and its physical properties, such as for example its spin. The two up and the single down quarks that comprise the proton in the simplest picture account only for a few percent of the proton mass, the bulk of which is in the form of quark kinetic and potential energy and gluon energy from the strong force. An essential feature of this force, as described by quantum chromodynamics, is its ability to create matter-antimatter quark pairs inside the proton that exist only for a very short time. Their fleeting existence makes the antimatter quarks within protons difficult to study, but their existence is discernible in reactions where a matter-antimatter quark pair annihilates. In this picture of quark-antiquark creation by the strong force, the probability distributions as a function of momentum for the presence of up and down antimatter quarks should be nearly identical, since their masses are quite similar and small compared to the mass of the proton. In the present manuscript, we show evidence from muon pair production measurements that these distributions are significantly different, with more abundant down antimatter quarks than up antimatter quarks over a wide range of momentum. These results revive interest in several proposed mechanisms as the origin of this antimatter asymmetry in the proton that had been disfavored by the previous results and point to the future measurements that can distinguish between these mechanisms., 10 pages, 5 figures, 5 tables; Matches published version

Background: Measurements of exclusive meson production are a useful tool in the study of hadronic structure. In particular, one can discern the relevant degrees of freedom at different distance scales through these studies. Purpose: To study the transition between non-perturbative and perturbative Quantum Chromodyanmics as the square of four momentum transfer to the struck proton, -t, is increased. Method: Cross sections for the $^1$H(e,e'$\pi^+$)n reaction were measured over the -t range of 0.272 to 2.127 GeV$^2$ with limited azimuthal coverage at fixed beam energy of 4.709 GeV, Q$^2$ of 2.4 GeV$^2$ and W of 2.0 GeV at the Thomas Jefferson National Accelerator Facility (JLab) Hall C. Results: The -t dependence of the measured $\pi^+$ electroproduction cross section generally agrees with prior data from JLab Halls B and C. The data are consistent with a Regge amplitude based theoretical model, but show poor agreement with a Generalized Parton Distribution (GPD) based model. Conclusion: The agreement of cross sections with prior data implies small contribution from the interference terms, and the confirmation of the change in t-slopes between the low and high -t regions previously observed in photoproduction indicates the changing nature of the electroproduction reaction in our kinematic regime., Comment: 9 pages, 5 figures Physical Review C, in press

The $^{12}\mathrm{C}(\ensuremath{\alpha},\ensuremath{\gamma})^{16}\mathrm{O}$ reaction, an important component of stellar helium burning, plays a key role in nuclear astrophysics. It has direct impact on the evolution and final state of massive stars, while also influencing the elemental abundances resulting from nucleosynthesis in such stars. Providing a reliable estimate for the energy dependence of this reaction at stellar helium burning temperatures has been a major goal for the field. In this work, we study the role of potential new measurements of the inverse reaction, $^{16}\mathrm{O}(\ensuremath{\gamma},\ensuremath{\alpha})^{12}\mathrm{C}$, in reducing the overall uncertainty. A multilevel $R$-matrix analysis is used to make extrapolations of the astrophysical $S$ factor for this reaction to the stellar energy of 300 keV. The statistical precision of the $S$-factor extrapolation is determined by performing multiple fits to existing $E1$ and $E2$ ground-state capture data, including the impact of possible future measurements of the $^{16}\mathrm{O}(\ensuremath{\gamma},\ensuremath{\alpha})^{12}\mathrm{C}$ reaction. In particular, we consider a proposed Jefferson Laboratory (JLab) experiment that will make use of a high-intensity low-energy bremsstrahlung beam that impinges on an oxygen-rich single-fluid bubble chamber in order to measure the total cross section for the inverse reaction. The importance of low-energy data as well as high-precision data is investigated.

Author(s): Aidala, CA; Arrington, JR; Ayuso, C; Bowen, BM; Bowen, ML; Bowling, KL; Brown, AW; Brown, CN; Byrd, R; Carlisle, RE; Chang, T; Chang, WC; Chen, A; Chen, JY; Christian, DC; Chu, X; Dannowitz, BP; Daugherity, M; Diefenthaler, M; Dove, J; Durandet, C; El Fassi, L; Erdos, E; Fox, DM; Geesaman, DF; Gilman, R; Goto, Y; Guo, L; Guo, R; Hague, T; Hicks, CR; Holt, RJ; Isenhower, D; Jiang, X; Katich, JM; Kerns, BM; Kinney, ER; Kitts, ND; Klein, A; Kleinjan, D; Kras, J; Kudo, Y; Lin, PJ; Liu, D; Liu, K; Liu, MX; Lorenzon, W; Makins, NCR; Martinez, JD; McClellan, RE; McDonald, B; McGaughey, PL; McNease, SE; Medeiros, MM; Miller, B; Miller, AJ; Miyasaka, S; Miyachi, Y; Mooney, IA; Morton, DH; Nadim, B; Nagai, K; Nakahara, K; Nakano, K; Nara, S; Obata, S; Peng, JC; Prasad, S; Puckett, AJR; Ramson, BJ; Raymond, RS; Reimer, PE; Rubin, JG; Salinas, R; Sanftl, F; Sawada, S; Sawada, T; Scott, MBC; Selensky, LE; Shibata, TA; Shiu, S; Su, D; Tadepalli, AS; Teo, M; Tice, BG | Abstract: The SeaQuest spectrometer at Fermilab was designed to detect oppositely-charged pairs of muons (dimuons) produced by interactions between a 120 GeV proton beam and liquid hydrogen, liquid deuterium and solid nuclear targets. The primary physics program uses the Drell–Yan process to probe antiquark distributions in the target nucleon. The spectrometer consists of a target system, two dipole magnets and four detector stations. The upstream magnet is a closed-aperture solid iron magnet which also serves as the beam dump, while the second magnet is an open aperture magnet. Each of the detector stations consists of scintillator hodoscopes and a high-resolution tracking device. The FPGA-based trigger compares the hodoscope signals to a set of pre-programmed roads to determine if the event contains oppositely-signed, high-mass muon pairs.

The $^{12}$C($\alpha,\gamma$)$^{16}$O reaction, an important component of stellar helium burning, plays a key role in nuclear astrophysics. It has direct impact on the evolution and final state of massive stars, while also influencing the elemental abundances resulting from nucleosynthesis in such stars. Providing a reliable estimate for the energy dependence of this reaction at stellar helium burning temperatures has been a major goal for the field. In this work, we study the role of potential new measurements of the inverse reaction, $^{16}$O($\gamma,\alpha$)$^{12}$C, in reducing the overall uncertainty. A multilevel R-matrix analysis is used to make extrapolations of the astrophysical S factor for this reaction to the stellar energy of 300 keV. The statistical precision of the S-factor extrapolation is determined by performing multiple fits to existing E1 and E2 ground state capture data, including the impact of possible future measurements of the $^{16}$O($\gamma,\alpha$)$^{12}$C reaction. In particular, we consider a proposed JLab experiment that will make use of a high-intensity low-energy bremsstrahlung beam that impinges on an oxygen-rich single-fluid bubble chamber in order to measure the total cross section for the inverse reaction. The importance of low energy data as well as high precision data is investigated.

A system of modular sealed gas target cells has been developed for use in electron scattering experiments at the Thomas Jefferson National Accelerator Facility (Jefferson Lab). This system was initially developed to complete the MARATHON experiment which required, among other species, tritium as a target material. Thus far, the cells have been loaded with the gas species 3H, 3He, 2H, 1H and 40Ar and operated in nominal beam currents of up to 22.5 uA in Jefferson Lab's Hall A. While the gas density of the cells at the time of loading is known, the density of each gas varies uniquely when heated by the electron beam. To extract experimental cross sections using these cells, density dependence on beam current of each target fluid must be determined. In this study, data from measurements with several beam currents within the range of 2.5 to 22.5 uA on each target fluid are presented. Additionally, expressions for the beam current dependent fluid density of each target are developed., 8 pages, 12 figures, 4 tables

Structure functions, as measured in lepton-nucleon scattering, have proven to be very useful in studying the partonic dynamics within the nucleon. However, it is experimentally difficult to separately determine the longitudinal and transverse structure functions, and consequently there are substantially less data available in particular for the longitudinal structure function. Here, we present separated structure functions for hydrogen and deuterium at low four-momentum transfer squared, Q2

Proton electromagnetic form factors are among the most important sources of information about the internal structure of the proton. Two different methods for measuring these form factors, the method proposed by Rosenbluth and the polarization-transfer method, yield contradictory results. It is assumed that this contradiction can be removed upon taking into account the hard part of the contribution of two-photon exchange to the cross section for elastic electron-proton scattering. This contribution can measured experimentally via a precision comparison of the cross sections for the elastic scattering of positrons and electrons on protons. Such a measurement, performed at the VEPP-3 storage ring in Novosibirsk at the beam energies of 1.6 and 1.0 GeV for positron (electron) scattering angles in the ranges of θ e = 15°–25° and 55°–75° in the first case and in the range of θ e = 65°–105° in the second case is described in the present article. Preliminary results of this experiment and their comparison with theoretical predictions are described.

The H1(e,e′K+)Λ reaction was studied as a function of the Mandelstam variable -t using data from the E01-004 (FPI-2) and E93-018 experiments that were carried out in Hall C at the 6 GeV Jefferson Laboratory. The cross section was fully separated into longitudinal and transverse components, and two interference terms at four-momentum transfers Q2 of 1.00, 1.36, and 2.07GeV2. The kaon form factor was extracted from the longitudinal cross section using the Regge model by Vanderhaeghen et al. [Phys. Rev. C 57, 1454 (1998)PRVCAN0556-281310.1103/PhysRevC.57.1454]. The results establish the method, previously used successfully for pion analyses, for extracting the kaon form factor. Data from 12 GeV Jefferson Laboratory experiments are expected to have sufficient precision to distinguish between theoretical predictions, for example, recent perturbative QCD calculations with modern parton distribution amplitudes. The leading-twist behavior for light mesons is predicted to set in for values of Q2 between 5 and 10GeV2, which makes data in the few-GeV regime particularly interesting. The Q2 dependence at fixed x and -t of the longitudinal cross section that we extracted seems consistent with the QCD factorization prediction within the experimental uncertainty.

Symmetry permeates nature and is fundamental to all laws of physics. One example is parity (mirror) symmetry, which implies that flipping left and right does not change the laws of physics. Laws for electromagnetism, gravity and the subatomic strong force respect parity symmetry, but the subatomic weak force does not. Historically, parity violation in electron scattering has been important in establishing (and now testing) the standard model of particle physics. One particular set of quantities accessible through measurements of parity-violating electron scattering are the effective weak couplings C2q, sensitive to the quarks' chirality preference when participating in the weak force, which have been measured directly only once in the past 40 years. Here we report a measurement of the parity-violating asymmetry in electron-quark scattering, which yields a determination of 2C2u - C2d (where u and d denote up and down quarks, respectively) with a precision increased by a factor of five relative to the earlier result. These results provide evidence with greater than 95 per cent confidence that the C2q couplings are non-zero, as predicted by the electroweak theory. They lead to constraints on new parity-violating interactions beyond the standard model, particularly those due to quark chirality. Whereas contemporary particle physics research is focused on high-energy colliders such as the Large Hadron Collider, our results provide specific chirality information on electroweak theory that is difficult to obtain at high energies. Our measurement is relatively free of ambiguity in its interpretation, and opens the door to even more precise measurements in the future.

© 2019 IOP Publishing Ltd and Sissa Medialab. A cryogenic apparatus is described that enables a new experiment, nEDM@SNS, with a major improvement in sensitivity compared to the existing limit in the search for a neutron Electric Dipole Moment (EDM). This apparatus uses superfluid 4He to produce a high density of Ultra-Cold Neutrons (UCN) which are contained in a suitably coated pair of measurement cells. The experiment, to be operated at the Spallation Neutron Source at Oak Ridge National Laboratory, uses polarized 3He from an Atomic Beam Source injected into the superfluid 4He and transported to the measurement cells where it serves as a co-magnetometer. The superfluid 4He is also used as an insulating medium allowing significantly higher electric fields, compared to previous experiments, to be maintained across the measurement cells. These features provide an ultimate statistical uncertainty for the EDM of 2-3× 10-28 e-cm, with anticipated systematic uncertainties below this level.

We have devised a technique for measuring some of the most important nuclear reactions in stars which we expect to provide considerable improvement over previous experiments. Adapting ideas from dark matter search experiments with bubble chambers, we have found that a superheated liquid is sensitive to recoils produced from γ rays photodisintegrating the nuclei of the liquid. The main advantage of the new target-detector system is a gain in yield of six orders of magnitude over conventional gas targets due to the higher mass density of liquids. Also, the detector is practically insensitive to the γ -ray beam itself, thus allowing it to detect only the products of the nuclear reaction of interest. The first set of tests of a superheated target with a narrow bandwidth γ -ray beam was completed and the results demonstrate the feasibility of the scheme. The new data are successfully described by an R-matrix model using published resonance parameters. With the increase in luminosity of the next generation γ -ray beam facilities, the measurement of thermonuclear rates in the stellar Gamow window would become possible.

Background: Octupole-deformed nuclei, such as that of $^{225}\mathrm{Ra}$, are expected to amplify observable atomic electric dipole moments (EDMs) that arise from time-reversal and parity-violating interactions in the nuclear medium. In 2015 we reported the first ``proof-of-principle'' measurement of the $^{225}\mathrm{Ra}$ atomic EDM.Purpose: This work reports on the first of several experimental upgrades to improve the statistical sensitivity of our $^{225}\mathrm{Ra}$ EDM measurements by orders of magnitude and evaluates systematic effects that contribute to current and future levels of experimental sensitivity.Method: Laser-cooled and trapped $^{225}\mathrm{Ra}$ atoms are held between two high-voltage electrodes in an ultrahigh-vacuum chamber at the center of a magnetically-shielded environment. We observe Larmor precession in a uniform magnetic field using nuclear-spin-dependent laser light scattering and look for a phase shift proportional to the applied electric field, which indicates the existence of an EDM. The main improvement to our measurement technique is an order-of-magnitude increase in spin-precession time, which is enabled by an improved vacuum system and a reduction in trap-induced heating.Results: We have measured the $^{225}\mathrm{Ra}$ atomic EDM to be less than $1.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}23}\phantom{\rule{4pt}{0ex}}e$ cm ($95%$ confidence upper limit), which is a factor of 36 improvement over our previous result.Conclusions: Our evaluation of systematic effects shows that this measurement is completely limited by statistical uncertainty. Combining this measurement technique with planned experimental upgrades, we project a statistical sensitivity at the $1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}28}\phantom{\rule{4pt}{0ex}}e$ cm level and a total systematic uncertainty at the $4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}29}\phantom{\rule{4pt}{0ex}}e$ cm level.

We have measured the nuclear transparency of the incoherent diffractive A(e,e′ρ0) process in 12C and 56Fe targets relative to 2H using a 5 GeV electron beam. The nuclear transparency, the ratio of the produced ρ0ʼs on a nucleus relative to deuterium, which is sensitive to ρA interaction, was studied as function of the coherence length (lc), a lifetime of the hadronic fluctuation of the virtual photon, and the four-momentum transfer squared (Q2). While the transparency for both 12C and 56Fe showed no lc dependence, a significant Q2 dependence was measured, which is consistent with calculations that included the color transparency effects.

We report on the status of the Novosibirsk experiment on a precision measurement of the ratio $R$ of the elastic $e^+ p$ and $e^- p$ scattering cross sections. Such measurements determine the two-photon exchange effect in elastic electron-proton scattering. The experiment is conducted at the VEPP-3 storage ring using a hydrogen internal gas target. The ratio $R$ is measured with a beam energy of 1.6 GeV (electron/positron scattering angles are $\theta = 55 \div 75^{\circ}$ and $\theta = 15 \div 25^{\circ}$) and 1 GeV ($\theta = 65 \div 105^{\circ}$). We briefly describe the experimental method, paying special attention to the radiative corrections. Some preliminary results are presented., Comment: 5 pages, 6 figures and 1 table; contribution to the Proceedings of the PHIPSI11 Workshop (Novosibirsk, Russia, 19-22 September 2011)

Luminescent Solar Concentrators (LSCs) use fluorescent materials and light guides to convert direct and diffuse sunlight into concentrated wavelength-shifted light that produces electrical power in small photovoltaic (PV) cells with the goal of significantly reducing the cost of solar energy utilization. In this paper we present an optimization analysis based on the implementation of a genetic algorithm (GA) subroutine to a numerical ray-tracing Monte Carlo model of an LSC, SIMSOLAR-P. The initial use of the GA implementation in SIMSOLAR-P is to find the optimal parameters of a hypothetical “perfect luminescent material” that obeys the Kennard Stepanov (K-S) thermodynamic relationship between emission and absorption. The optimization balances the efficiency losses in the wavelength shift and PV conversion with the efficiency losses due to re-scattering of light out of the collector. The theoretical limits of efficiency are provided for one, two and three layer configurations; the results show that a single layer configuration is far from optimal and adding a second layer in the LSC with wavelength shifted material in the near infrared region significantly increases the power output, while the gain in power by adding a third layer is relatively small. The results of this study provide a theoretical upper limit to the performance of an LSC and give guidance for the properties required for luminescent materials, such as quantum nanocrystals, to operate efficiently in planar LSC configurations.

We report a new, high-precision measurement of the proton elastic form factor ratio μ p G E / G M for the four-momentum transfer squared Q 2 = 0.3 – 0.7 ( GeV / c ) 2 . The measurement was performed at Jefferson Lab (JLab) in Hall A using recoil polarimetry. With a total uncertainty of approximately 1%, the new data clearly show that the deviation of the ratio μ p G E / G M from unity observed in previous polarization measurements at high Q 2 continues down to the lowest Q 2 value of this measurement. The updated global fit that includes the new results yields an electric (magnetic) form factor roughly 2% smaller (1% larger) than the previous global fit in this Q 2 range. We obtain new extractions of the proton electric and magnetic radii, which are 〈 r E 2 〉 1 / 2 = 0.875 ± 0.010 fm and 〈 r M 2 〉 1 / 2 = 0.867 ± 0.020 fm . The charge radius is consistent with other recent extractions based on the electron–proton interaction, including the atomic hydrogen Lamb shift measurements, which suggests a missing correction in the comparison of measurements of the proton charge radius using electron probes and the recent extraction from the muonic hydrogen Lamb shift.

We discuss the prospects for parity violation experiments in atomic hydrogen and deuterium to contribute to testing the Standard Model (SM). We find that, if parity experiments in hydrogen can be done, they remain highly desirable because there is negligible atomic-physics uncertainty and low energy tests of weak neutral current interactions are needed to probe for new physics beyond the SM. Analysis of a generic APV experiment in deuterium indicates that a 0.3% measurement of C1D requires development of a slow (77K) metastable beam of ≈ 5×1014D(2S)s − 1 per hyperfine component. The advent of UV radiation from free electron laser (FEL) technology could allow production of such a beam.

Novel experimental techniques are required to make the next big leap in neutron electric dipole moment experimental sensitivity, both in terms of statistics and systematic error control. The nEDM experiment at the Spallation Neutron Source (nEDM@SNS) will implement the scheme of Golub & Lamoreaux [Phys. Rep., 237, 1 (1994)]. The unique properties of combining polarized ultracold neutrons, polarized $^3$He, and superfluid $^4$He will be exploited to provide a sensitivity to $\sim 10^{-28}\,e{\rm \,\cdot\, cm}$. Our cryogenic apparatus will deploy two small ($3\,{\rm L}$) measurement cells with a high density of ultracold neutrons produced and spin analyzed in situ. The electric field strength, precession time, magnetic shielding, and detected UCN number will all be enhanced compared to previous room temperature Ramsey measurements. Our $^3$He co-magnetometer offers unique control of systematic effects, in particular the Bloch-Siegert induced false EDM. Furthermore, there will be two distinct measurement modes: free precession and dressed spin. This will provide an important self-check of our results. Following five years of "critical component demonstration," our collaboration transitioned to a "large scale integration" phase in 2018. An overview of our measurement techniques, experimental design, and brief updates are described in these proceedings., Submitted to proceedings of PPNS 2018 - International Workshop on Particle physics at Neutron Sources (https://www.webofconferences.org/epj-web-of-conferences-forthcoming-conferences/1148-ppns-2018)

Permanent electric dipole moments (EDMs) in atoms or molecules are a signature of time-reversal and parity violation and represent an important window onto physics beyond the Standard Model. We are developing a next generation EDM search based on laser-cooled and trapped {sup 225}Ra atoms. Due to octupole deformation of the nucleus, {sup 225}Ra is predicted to be two to three orders of magnitude more sensitive to T-violating interactions than {sup 199}Hg, which currently sets the most stringent limits in the nuclear sector. We will discuss progress toward realizing a first EDM measurement for {sup 225}Ra.

An experimental and theoretical perspective is provided on the behavior of unpolarized distribution functions for the nucleon and pion on the valence-quark domain, namely, Bjorken x(greater-or-similar sign)0.4. This domain is a key to much of hadron physics; e.g., a hadron is defined by its flavor content and that is a valence-quark property. Furthermore, its accurate parametrization is crucial to the provision of reliable input for large collider experiments. The focus is on experimental extractions of distribution functions via electron and muon inelastic scattering, and from Drell-Yan interactions; and on theoretical treatments that emphasize an explanation of the distribution functions, providing an overview of major contemporary approaches and issues. Valence-quark physics is a compelling subject, which probes at the heart of our understanding of the standard model. There are numerous outstanding and unresolved challenges, which experiment and theory must confront. In connection with experiment, an explanation that an upgraded Jefferson Laboratory facility is well suited to provide new data on the nucleon is provided, while a future electron-ion collider could provide essential new data for the mesons. There is also great potential in using Drell-Yan interactions, at FNAL, CERN, J-PARC, and GSI, to push into the large-x domain for both mesonsmore » and nucleons. Furthermore, it is argued that explanation, in contrast to modeling and parametrization, requires a widespread acceptance of the need to adapt theory: to the lessons learnt already from the methods of nonperturbative quantum-field theory and a fuller exploitation of those methods.« less

An overview of the recently completed, current, and planned experiments with internal targets at the VEPP-3 electron-positron storage ring in Novosibirsk is given. The results of the experiment to separately measure the deuteron form factors in elastic ed scattering in the range of momentum transfer Q 2 = 8−15 fm−2 are provided. The results of measuring the tensor analyzing power components of the tensor-polarized deuteron photodisintegration reaction in the range of γ-quantum energies E γ = 25−600 MeV are presented. The tensor analyzing powers of the coherent photoproduction of a neutral pion on a tensor-polarized deuteron have been measured for the first time. The almost-real photon tagging system being created is discussed. The status of the experiment under way to determine the contribution of two-photon exchange to the elastic ep scattering cross section is described.

SUMMARY Five children with congenital anatomical abnormalities were treated orally with 5–fluorocytosine for severe urinary candidosis, following prolonged anti-bacterial therapy. Dosage was started at 50mg/kg/day at 6–hourly intervals and was continued for 4 to 6 weeks. Numerous serum and urine assays were made. Urine samples soon became negative on microscopic and cultural examination, except in one case where a more resistant variant of Candida appeared during therapy, necessitating a higher dosage. No clinical, haema-tological or biochemical side-effects were noted. Four children with congenital anatomical abnormalities received 100mg/kg/day of ‘Clotrimazole’ for several weeks for the treatment of severe urinary candidosis; two of the children also had candidaemia. Candida was eliminated in three of the patients; the fourth failed to respond and was successfully treated on 5–fluorocytosine. Serum, faecal and urine assays were made by a microbiological method. No side-effects were noted. RESUME Traitement de candidoses urinaires par les medications antifungiques orales 5–fluorocytoine y Clotrimazole Cinq enfants presentant des anomalies anatomiques congenitales ont ete traites par la 5–fluorocytosine pour candidose urinaire grave, e la suite d'une antibiotherapie prolongee. Les doses ont debute a 50 mg/kg/jour a six heures d'intervalle et ont ete continuees durant cinq e six semaines. De nombreux controles seriques et urinaires ont ete effectues. Les prelevements urinaires sont apparus rapidement negatifs a l'examen microscopique et en culture a l'exception d'un cas marque par une variante tres resistante de candida et necessi-tant des doses plus elevees. Aucun effet secondaire, clinique, hematologique ou biochimique n'a ete observe. Quatre enfants presentant egalement des anomalies anatomiques congenitales furent traites par 100 mg/kg/jour de Clotrimazole durant plusieurs semaines pour candidose urinaire grave; deux des enfants presentaient egalement une candidaemie. Les candidas furent supprimes chez trois des malades. II n'y eut pas d'effect chez le quatrieme et un traitement par la fluorocytosine fut entrepris. Traitement couronne de succes. Des examens du serum, des matieres et des urines furent effectues par methode microbiologique. Aucun effet secondaire n'a ete observe. ZUSAMMENFASSUNG Die Behandlung der Harnwegscandidose mit den oralen antifungal wirkenden Mitteln 5–Fluorocytosin und Clotrimazol Funf Kinder mit angeborenen anatomischen Misbildungen wurden wegen schwere Harnwegscandidose oral mit 5–Fluorocytosin und anschliesend uber eine langere Zeit antibiotisch behandelt. Die Dosis betrug 50 mg/kg/die, verabreicht in 6–stundlichen Tnter-vallen uber eine Zeit von 4–6 Wochen. Es wurden wiederholt Serum- und Urinkontrollen durchgefuhrt. Das Urinsediment normalisierte sich sehr bald und die Kultur wurde steril auser in einem Fall, bei dem unter der Therapie ein resistenter Candidastamm auftrat, so das eine hoher Dosierung erforderlich war. Klinisch, hamatologisch und biochemisch wurden keine Nebenwirkungen nachgewiesen. Vier Kinder mit angeborenen anatomischen Misbildungen erhielten 100 mg/kg/die Clotrimazol uber mehrere Wochen zur Behandlung schwerer Harnwegscandidose, zwei der Kinder hatten auserdem eine Candidamie. Bei drei der Patienten wurde die Candidose erfolgreich behandelt, der vierte Patient sprach nicht an, wurde dann aber erfolgreich mit 5–Fluorocytosin behandelt. Die Serum-, Stuhl- und Urinuntersuchungen wurden anhand von Mikromethoden durchgefuhrt. Es wurden keine Nebenwirkungen beobachtet. RESUMEN Trataminento de la candidiasis urinaria con los fdrmacos antfungicos oroles 5–fluorocytosine y Clotrimazole Cinco ninos con anomalias anatomicas congenitas fueron tratadas oralmente con 5–fluorocytosine por candidiasis urinaria grave, consecutiva a una terapeutica antibacteriana prolongada. La dosificacion se inicio con 50 mg/kg/dia con intervalos de 6 horas y durante 4–6 semanas. Se realizaron numerosos analisis de suero y orina. Las muestras de orina se negativizaron precozmente al niicroscopio y en cultivo, excepto en un caso en que aparecio durante el tratamiento una variante mas resistente de candida, precisandose una dosis mas alta. No se observo ningun efecto secundario clinico, hematologico o bioquimico. Cuatro ninos con anomalias anatomicas congenitas recibieron 100 mg/kg/dia de Clotrimazole durante varias semanas para el tratamiento de candidiasis urinaria grave, dos de los ninos tenian tambien candidemia. La candida fue eliminada en tres de los pacientes; el 4; no respondio y fue tratado con exito con 5–fluorocytosine. Se realizaron analisis microbiologicos de suero, heces y orina. No se registraron efectos secundarios.

SUMMARY The bacteria responsible for the colonisation of ventriculo-atrial shunts invariably belong to the subgroup Staphylococcus IT. Observations suggest that the distal catheter may cause 86 local trauma and the formation of thrombi, to which the bacteria adhere and subsequently colonise the valve. The use of a laboratory model of the shunt showed that an ascending counter-current infection can readily occur with S.11 coccus. The prevention of colonization depends largely on prophylactic antibacterial therapy, and the long-term use of fucidin is suggested as a possible course. RESUME Etude bacteriologique des shunts atrio-ventriculaires infectes Les germes responsables de l'infestation des shunts atrio-ventriculaires appartiennent invariablement au sub-groupe staphylocoque II. Les observations suggerent que le catheter distal peut causer des traumatismes locaux et la formation de thrombi, auxquels les germes adherent, contaminant la valve ulterieurement. L'utilisation en laboratoire d'un modele de shunt montre qu'une infection ascendante a contre-courant peut rapidement survenir avec le staphylocoque II. La prevention de l'infestation depend largement du traitement anti-bacterien preventif et l'emploi a long terme de fucidine est donne en exemple. ZUSAMMENFASSUNG Bakteriologische Studien auf besiedelten ventriculo-atrialen Shunts Die fur die Besiedelung von ventriculo-atrialen Shunts verantwortlichen Bakterien gehoren regelmasig zur Untergruppe Staphylococcus II. Die Beobachtungen machen es wahrscheinlich, das der distale Katheter ein lokales Trauma und die Bildung von Thromben verursacht, an denen die Bakterien hangen und in der Folge die Klappe besiedeln. Die Verwendung eines Labormodells des Shunts zeigte, das mit dem S II Kokkus leicht eine aufsteigende Infektion moglich ist. Es hangt weitgehend von einer prophylaktischen anti-bakteriellen Therapie ab, die Besiedelung zu verhindern, und die Langzeitgabe von Fucidin wird als eine Moglichkeit angeregt. RESUMEN Estudios bacterialogicos en derivaciones ventriculo-atriales colonizadas Las bacterias responsables de la colonizaci6n pertenecen invariablemente al subgrupo Estafilococo II. Las observaciones sugieren que el cateter distal puede causar un trauma local y la formacion de trombos, a los cuales la bacteria se adhiere con la colonizacion subsiguiente de la valvula. La utilizacion de un modelo de laboratono de la derivation, mostro que una infeccion ascendente a contracorriente puede tener lugar con facilidad con Estreptococos-II. La prevention de la colonization depende en gran manera de la terapia profilactica anti-bacteriana, sugiriedose la utilization de fucidina por largo tiempo.

This White Paper presents the science case of an Electron-Ion Collider (EIC), focused on the structure and interactions of gluon-dominated matter, with the intent to articulate it to the broader nuclear science community. It was commissioned by the managements of Brookhaven National Laboratory (BNL) and Thomas Jefferson National Accelerator Facility (JLab) with the objective of presenting a summary of scientific opportunities and goals of the EIC as a follow-up to the 2007 NSAC Long Range plan. This document is a culmination of a community-wide effort in nuclear science following a series of workshops on EIC physics and, in particular, the focused ten-week program on "Gluons and quark sea at high energies" at the Institute for Nuclear Theory in Fall 2010. It contains a brief description of a few golden physics measurements along with accelerator and detector concepts required to achieve them, and it benefited from inputs from the users' communities of BNL and JLab. This White Paper offers the promise to propel the QCD science program in the U.S., established with the CEBAF accelerator at JLab and the RHIC collider at BNL, to the next QCD frontier., Comment: The Second Edition, 164 pages

An intense, 120 GeV proton beam incident on an extremely long, iron target generates enormous numbers of light-mass particles that also decay within that target. If one of these particles decays to a final state with a hidden gauge boson, or if such a particle is produced as a result of the initial collision, then that weakly interacting, hidden-sector particle may traverse the remainder of the target and be detected downstream through its possible decay to an $e^+e^-$, $\mu^+\mu^-$, or $\pi^+\pi^-$ final state. These conditions can be realized through an extension of the SeaQuest experiment at Fermilab, and in this initial investigation we consider how it can serve as an ultrasensitive probe of hidden vector gauge forces, both Abelian and non-Abelian. A light, weakly coupled hidden sector may well explain the dark matter established through astrophysical observations, and the proposed search can provide tangible evidence for its existence --- or, alternatively, constrain a "sea" of possibilities., Comment: 14 pages, 8 figures; improved sensitivity analysis and cross-checks; small shifts in the expected limits; conclusions unchanged; refs. added

Researchers have devised a new technique to look for evidence of a permanent electric dipole moment in atoms, which would signal new physics.

The ratio of the elastic ${e}^{+}p$ to ${e}^{\ensuremath{-}}p$ scattering cross sections has been measured precisely, allowing the determination of the two-photon exchange contribution to these processes. This neglected contribution is believed to be the cause of the discrepancy between the Rosenbluth and polarization transfer methods of measuring the proton electromagnetic form factors. The experiment was performed at the VEPP-3 storage ring at beam energies of 1.6 and 1.0 GeV and at lepton scattering angles between 15\ifmmode^\circ\else\textdegree\fi{} and 105\ifmmode^\circ\else\textdegree\fi{}. The data obtained show evidence of a significant two-photon exchange effect. The results are compared with several theoretical predictions.

SUMMARY.— The production of esterase and lipase by aerobic bacteria from normal human skin surfaces was tested by simple plate tests against natural and artificial substrates. Almost all of 42 strains of Micrococcaceae representative of each of Baird-Parker's subgroups produced strong esterases and lipases, as did most of the 82 strains of Sarcina spp., especially those most commonly present on healthy skin. Forty per cent of 50 aerobic skin diphtheroids and 20% of 58 aerobic nasal diphtheroids produced active lipases.

We report on the progress towards measuring the charge radius of 6 He and 8 He nuclei by performing laser spectroscopy on these helium atoms in a magneto-optical trap (MOT). First tests to produce neutral 6 He atoms via the 12 C( 7 Li, 6 He) 13 N reaction at the ATLAS accelerator have been successfully conducted. The MOT apparatus including the laser system and the discharge source to populate the metastable level are currently being set up.

A bubble chamber has been developed to be used as an active target system for low energy nuclear astrophysics experiments. Adopting ideas from dark matter detection with superheated liquids, a detector system compatible with gamma-ray beams has been developed. This detector alleviates some of the limitations encountered in standard measurements of the minute cross sections of interest to stellar environments. While the astrophysically relevant nuclear reaction processes at hydrostatic burning temperatures are dominated by radiative captures, in this experimental scheme we measure the time-reversed processes. Such photodisintegrations allow us to compute the radiative capture cross sections when transitions to excited states of the reaction products are negligible. Due to the transformation of phase space, the photodisintegration cross sections are up to two orders of magnitude higher. The main advantage of the new target-detector system is a density several orders of magnitude higher than conventional gas targets. Also, the detector is virtually insensitive to the gamma-ray beam itself, thus allowing us to detect only the products of the nuclear reaction of interest. The development and the operation as well as the advantages and disadvantages of the bubble chamber are discussed., Accepted manuscript in Nuclear Instruments and Methods in Physics Research Section A. 12 pages, 14 figures

We are searching for a permanent EDM of the 225 Ra atom. Recently we have observed spin precession of 225 Ra atoms in parallel electric and magnetic fields.

The ratio of the elastic e(+)p to e(-)p scattering cross sections has been measured precisely, allowing the determination of the two-photon exchange contribution to these processes. This neglected contribution is believed to be the cause of the discrepancy between the Rosenbluth and polarization transfer methods of measuring the proton electromagnetic form factors. The experiment was performed at the VEPP-3 storage ring at beam energies of 1.6 and 1.0 GeV and at lepton scattering angles between 15° and 105°. The data obtained show evidence of a significant two-photon exchange effect. The results are compared with several theoretical predictions.

We describe a precise measurement of the ratio of the ( e + p ) to ( e − p ) elastic scattering cross sections. This comparison is sensitive to the effect of two-photon exchange contributions which may be the cause for inconsistent extractions of the proton form factors obtained using different methods. The experiment was performed at storage ring VEPP–3, Novosibirsk at energies of positron/electron beams of 1.0 and 1.6 GeV with electron/positron scattering angles θ = 65÷105° for the first case and 15÷25° and 55÷75° for the second case. Details of the experiment and the preliminary results are presented.

Developments in spin-polarized internal targets for storage rings have permitted measurements of 197 MeV polarized protons scattering from vector polarized deuterons. This work presents measurements of the polarization observables A_y, iT_11, and C_y,y in proton-deuteron elastic scattering. When compared to calculations with and without three-nucleon forces, the measurements indicate that three-nucleon forces make a significant contribution to the observables. This work indicates that three-body forces derived from static nuclear properties appear to be crucial to the description of dynamical properties., 8 pages 2 figures Latex, submitted to Phys. Rev. Letters

A newly obtained data sample of inclusive electron-nucleon scattering from both hydrogen and deuterium targets is analyzed. These JLab data span the nucleon resonance region up to four-momentum transfers of 5 (GeV/c){sup 2} . The data are found to follow an average scaling curve. The inclusion of low-momentum transfer data yields a scaling curve resembling deep inelastic neutrino-nucleus scattering data, suggesting a sensitivity to valencelike structure only. (c) 2000 The American Physical Society.

We present a measurement of the longitudinal spin asymmetry A|| in photoproduction of pairs of hadrons with high transverse momentum pT. Data were accumulated by the HERMES experiment using a 27.5 GeV polarized positron beam and a polarized hydrogen target internal to the HERA storage ring. For h^+h^- pairs with _(pT)^(h1)>1.5GeV/c and _(pT)^(h2)>1.0GeV/c, the measured asymmetry is A_(||) = -0.28±0.12(stat)±0.02(syst). This negative value is in contrast to the positive asymmetries typically measured in deep inelastic scattering from protons, and is interpreted to arise from a positive gluon polarization.

Exclusive incoherent electroproduction of the ρ0(770) meson from 1H, 2H, 3He, and 14N targets has been studied by the HERMES experiment at squared four-momentum transfer Q^2>0.4 GeV^2 and positron energy loss ν from 9 to 20 GeV. The ratio of the 14N to 1H cross sections per nucleon, known as the nuclear transparency, was found to decrease with increasing coherence length of quark-antiquark fluctuations of the virtual photon. The data provide clear evidence of the interaction of the quark-antiquark fluctuations with the nuclear medium.

Spin-polarised atomic hydrogen is used as a gaseous polarised proton target in high energy and nuclear physics experiments operating with internal beams in storage rings. When such beams are intense and bunched, this type of target can be depolarised by a resonant interaction with the transient magnetic field generated by the beam bunches. This effect has been studied with the HERA positron beam in the HERMES experiment at DESY. Resonances have been observed and a simple analytic model has been used to explain their shape and position. Operating conditions for the experiment have been found where there is no significant target depolarisation due to this effect., REVTEX, 6 pages, 5 figures

The first measurements of the differential cross section for the d(gamma,p)n reaction up to 4.0 GeV were performed at Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. We report the cross sections at the proton center-of-mass angles of 36, 52, 69 and 89 degrees. These results are in reasonable agreement with previous measurements at lower energy. The 89 and 69 degree data show constituent-counting-rule behavior up to 4.0 GeV photon energy. The 36 and 52 degree data disagree with the counting rule behavior. The quantum chromodynamics (QCD) model of nuclear reactions involving reduced amplitudes disagrees with the present data., Comment: 5 pages (REVTeX), 1 figure (postscript)

We present the results of the first direct measurement of nuclear polarization in an optically pumped spin-exchange polarized deuterium target. Measurements of the nuclear tensor polarization p zz are made in a storage cell as a function of flow of deuterium nuclei. For these measurements, the optical pumping was performed on atoms in magnetic fields of 600 and 3600 G. These measurements verify that the spin-exchange method is capable of producing polarized deuterium nuclei without the use of rf transitions. The electronic polarization, P e , is also measured. The P e and p zz measurements at 600 G indicate that the system is in spin-temperature equilibrium, whereas the 3600 G measurements show signatures of non-equilibrium effects. P e is also measured with the system operated as a source of polarized atoms, with no storage cell. These measurements are compared with previous measurements using a similar source.

The (e,e'p) reaction was studies on targets of C, Fe, and Au at momentum transfers squared Q{sup 2} of 0.6, 1.3, 1.8 and 3.3 GeV{sup 2} in a region of kinematics dominated by quasifree electron-proton scattering. Missing energy and missing momentum distributions are reasonably well described by plane wave impulse approximation calculations with Q{sup 2} and A dependent corrections that measure the attenuation of the final state protons.