E. Frlez - University of Virginia

E. Frlez
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Name
E. Frlez
Affiliation
University of Virginia
City
Charlottesville
Country
United States

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High Energy Physics - Experiment (24)
 
Nuclear Experiment (16)
 
High Energy Physics - Phenomenology (8)
 
Physics - Instrumentation and Detectors (6)
 
Nuclear Theory (2)
 
Physics - Accelerator Physics (1)

Publications Authored By E. Frlez

Allowed charged $\pi$ meson decays are characterized by simple dynamics, few available decay channels, mainly into leptons, and extremely well controlled radiative and loop corrections. In that sense, pion decays represent a veritable triumph of the standard model (SM) of elementary particles and interactions. This relative theoretical simplicity makes charged pion decays a sensitive means for testing the underlying symmetries and the universality of weak fermion couplings, as well as for studying pion structure and chiral dynamics. Read More

We describe a detection system designed for precise measurements of angular correlations in neutron $\beta$ decay. The system is based on thick, large area, highly segmented silicon detectors developed in collaboration with Micron Semiconductor, Ltd. The prototype system meets specifications for $\beta$ electron detection with energy thresholds below 10 keV, energy resolution of $\sim$3 keV FWHM, and rise time of $\sim$50 ns with 19 of the 127 detector pixels instrumented. Read More

2015Jan
Authors: J. Grange, V. Guarino, P. Winter, K. Wood, H. Zhao, R. M. Carey, D. Gastler, E. Hazen, N. Kinnaird, J. P. Miller, J. Mott, B. L. Roberts, J. Benante, J. Crnkovic, W. M. Morse, H. Sayed, V. Tishchenko, V. P. Druzhinin, B. I. Khazin, I. A. Koop, I. Logashenko, Y. M. Shatunov, E. Solodov, M. Korostelev, D. Newton, A. Wolski, R. Bjorkquist, N. Eggert, A. Frankenthal, L. Gibbons, S. Kim, A. Mikhailichenko, Y. Orlov, D. Rubin, D. Sweigart, D. Allspach, G. Annala, E. Barzi, K. Bourland, G. Brown, B. C. K. Casey, S. Chappa, M. E. Convery, B. Drendel, H. Friedsam, T. Gadfort, K. Hardin, S. Hawke, S. Hayes, W. Jaskierny, C. Johnstone, J. Johnstone, V. Kashikhin, C. Kendziora, B. Kiburg, A. Klebaner, I. Kourbanis, J. Kyle, N. Larson, A. Leveling, A. L. Lyon, D. Markley, D. McArthur, K. W. Merritt, N. Mokhov, J. P. Morgan, H. Nguyen, J-F. Ostiguy, A. Para, C. C. Polly M. Popovic, E. Ramberg, M. Rominsky, D. Schoo, R. Schultz, D. Still, A. K. Soha, S. Strigonov, G. Tassotto, D. Turrioni, E. Villegas, E. Voirin, G. Velev, D. Wolff, C. Worel, J-Y. Wu, R. Zifko, K. Jungmann, C. J. G. Onderwater, P. T. Debevec, S. Ganguly, M. Kasten, S. Leo, K. Pitts, C. Schlesier, M. Gaisser, S. Haciomeroglu, Y-I. Kim, S. Lee, M-J Lee, Y. K. Semertzidis, K. Giovanetti, V. A. Baranov, V. N. Duginov, N. V. Khomutov, V. A. Krylov, N. A. Kuchinskiy, V. P. Volnykh, C. Crawford, R. Fatemi, W. P. Gohn, T. P. Gorringe, W. Korsch, B. Plaster, A. Anastasi, D. Babusci, S. Dabagov, C. Ferrari, A. Fioretti, C. Gabbanini, D. Hampai, A. Palladino, G. Venanzoni, T. Bowcock, J. Carroll, B. King, S. Maxfield, K. McCormick, A. Smith, T. Teubner, M. Whitley, M. Wormald, R. Chislett, S. Kilani, M. Lancaster, E. Motuk, T. Stuttard, M. Warren, D. Flay, D. Kawall, Z. Meadows, T. Chupp, R. Raymond, A. Tewlsey-Booth, M. J. Syphers, D. Tarazona, C. Ankenbrandt, M. A. Cummings, R. P. Johnson, C. Yoshikawa, S. Catalonotti, R. Di Stefano, M. Iacovacci, S. Mastroianni, S. Chattopadhyay, M. Eads, M. Fortner, D. Hedin, N. Pohlman, A. de Gouvea, H. Schellman, L. Welty-Rieger, T. Itahashi, Y. Kuno, K. Yai, F. Azfar, S. Henry, G. D. Alkhazov, V. L. Golovtsov, P. V. Neustroev, L. N. Uvarov, A. A. Vasilyev, A. A. Vorobyov, M. B. Zhalov, L. Cerrito, F. Gray, G. Di Sciascio, D. Moricciani, C. Fu, X. Ji, L. Li, H. Yang, D. Stöckinger, G. Cantatore, D. Cauz, M. Karuza, G. Pauletta, L. Santi, S. Baeßler, M. Bychkov, E. Frlez, D. Pocanic, L. P. Alonzi, M. Fertl, A. Fienberg, N. Froemming, A. Garcia, D. W. Hertzog J. Kaspar, P. Kammel, R. Osofsky, M. Smith, E. Swanson, T. van Wechel, K. Lynch

The Muon (g-2) Experiment, E989 at Fermilab, will measure the muon anomalous magnetic moment a factor-of-four more precisely than was done in E821 at the Brookhaven National Laboratory AGS. The E821 result appears to be greater than the Standard-Model prediction by more than three standard deviations. When combined with expected improvement in the Standard-Model hadronic contributions, E989 should be able to determine definitively whether or not the E821 result is evidence for physics beyond the Standard Model. Read More

The combination of simple dynamics, small number of available decay channels, and extremely well controlled radiative and loop corrections, make charged pion decays a sensitive means for testing the underlying symmetries and the universality of weak fermion couplings, as well as for improving our understanding of pion structure and chiral dynamics. This paper reviews the current state of experimental study of the allowed rare decays of charged pions: (a) leptonic, $\pi^+ \to e^+\nu_e$, or $\pi_{e2}$, (b) radiative, $\pi^+ \to e^+\nu_e\gamma$, or $\pi_{e2\gamma}$, and $\pi^+ \to e^+\nu_e e^+e^-$, or $\pi_{e2ee}$, and (c) semileptonic, $\pi^+\to \pi^0 e^+ \nu$, or $\pi_{e3}$. Taken together, the combined data set presents an internally consistent picture that also agrees well with standard model predictions. Read More

Simple dynamics, few available decay channels, and highly controlled radiative and loop corrections, make pion and muon decays a sensitive means of exploring details of the underlying symmetries. We review the current status of the rare decays: pi+ -> e+ nu, pi+ -> e+ nu gamma, pi+ -> pi0 e+ nu, and mu+ -> e+ nu nu-bar gamma. For the latter we report new preliminary values for the branching ratio B(E_gamma >10 MeV, theta_(e-gamma) > 30deg) = 4. Read More

2012Nov
Authors: The Mu2e Project, Collaboration, :, R. J. Abrams, D. Alezander, G. Ambrosio, N. Andreev, C. M. Ankenbrandt, D. M. Asner, D. Arnold, A. Artikov, E. Barnes, L. Bartoszek, R. H. Bernstein, K. Biery, V. Biliyar, R. Bonicalzi, R. Bossert, M. Bowden, J. Brandt, D. N. Brown, J. Budagov, M. Buehler, A. Burov, R. Carcagno, R. M. Carey, R. Carosi, M. Cascella, D. Cauz, F. Cervelli, A. Chandra, J. K. Chang, C. Cheng, P. Ciambrone, R. N. Coleman, M. Cooper, M. C. Corcoran, M. Cordelli, Y. Davydov, A. L. de Gouvea, L. De Lorenzis, P. T. Debevec, F. DeJongh, C. Densham, G. Deuerling, J. Dey, S. Di Falco, S. Dixon, R. Djilkibaev, B. Drendel, E. C. Dukes, A. Dychkant, B. Echenard, R. Ehrlich, N. Evans, D. Evbota, I. Fang, J. E. Fast, S. Feher, M. Fischler, M. Frank, E. Frlez, S. S. Fung, G. Gallo, G. Galucci, A. Gaponenko, K. Genser, S. Giovannella, V. Glagolev, D. Glenzinski, D. Gnani, S. Goadhouse, G. D. Gollin, C. Grace, F. Grancagnolo, C. Group, J. Hanson, S. Hanson, F. Happacher, E. Heckmaier, D. Hedin, D. W. Hertzog, R. Hirosky, D. G. Hitlin, E. Ho, X. Huang, E. Huedem, P. Q. Hung, E. V. Hungerford, T. Ito, W. Jaskierny, R. Jedziniak, R. P. Johnson, C. Johnstone, J. A. Johnstone, S. A. Kahn, P. Kammel, T. I. Kang, V. S. Kashikhin, V. V. Kashikhin, P. Kasper, D. M. Kawall, V. Khalatian, M. Kim, A. Klebaner, D. Kocen, Y. Kolomensky, I. Kourbanis, J. Kowalkowski, J. Kozminski, K. Krempetz, K. S. Kumar, R. K. Kutschke, R. Kwarciany, T. Lackowski, M. Lamm, M. Larwill, K. Lau, M. J. Lee, A. L'Erario, T. Leveling, G. Lim, C. Lindenmeyer, V. Logashenko, T. Lontadze, M. Lopes, A. Luca, K. R. Lynch, T. Ma, A. Maffezzoli, W. J. Marciano, M. Martini, W. Masayoshi, V. Matushko, M. McAteer, R. McCrady, A. Moccoli, L. Michelotti, J. P. Miller, S. Miscetti, W. Molzon, J. Morgan, A. Mukherjee, S. Nagaitsev, V. Nagaslaev, J. Niehoff, D. V. Neuffer, T. Nicol, A. J. Norman, B. Norris, J. Odell, S. Oh, Y. Oksuzian, G. Onorato, J. Orduna, D. Orris, R. Ostojic, T. Page, K. D. Paschke, G. Pauletta, T. Peterson, G. M. Piacentino, G. Pileggi, A. Pla-Dalmau, D. Pocanic, C. C. Polly, V. Polychronakos, B. Ponzio, M. Popovic, J. L. Popp, F. Porter, E. Presbys, P. Prieto, V. Pronskikh, F. Puccinelli, R. Rabehl, J. Ramsey, R. E. Ray, R. Rechenmacher, S. Rella, L. Ristori, R. Rivera, B. L. Roberts, T. J. Roberts, P. Rubinov, V. L. Rusu, A. Saputi, I. Sarra, Y. Smertzidis, P. Shanahan, A. Simonenko, J. Steward, I. Suslov, C. Sylvester, Z. Tang, M. Tartaglia, G. Tassielli, V. Tereshchenko, J. Theilacker, J. Tompkins, R. Tschirhart, G. Van Zandbergen, C. Vannini, G. Venanzoni, H. von der Lippe, R. Wagner, J. P. Walder, R. Walton, S. Wands, S. Wang, G. Warren, S. Werkema, H. B. White Jr, R. Wielgos, L. S. Wood, M. Woodward, J. Wu, M. Xiao, R. Yamada, P. Yamin, K. Yarritu, K. Yonehara, C. Yoshikawa, Z. You, G. Yu, A. Yurkewicz, G. Zavarise, R. Y. Zhu

Mu2e at Fermilab will search for charged lepton flavor violation via the coherent conversion process mu- N --> e- N with a sensitivity approximately four orders of magnitude better than the current world's best limits for this process. The experiment's sensitivity offers discovery potential over a wide array of new physics models and probes mass scales well beyond the reach of the LHC. We describe herein the conceptual design of the proposed Mu2e experiment. Read More

Building on the rare pion and muon decay results of the PIBETA experiment, the PEN collaboration has undertaken a precise measurement of B_{\pi e2} = R^\pi_{e/\mu}, the \pi^+ -> e^+\nu(\gamma) decay branching ratio, at the Paul Scherrer Institute, to reduce the present 40\times experimental precision lag behind theory to ~ 6-7\times. Because of large helicity suppression, R^\pi_{e/\mu} is uniquely sensitive to contributions from non-(V-A) physics, making this decay a particularly suitable subject of study. Even at current precision, the experimental value of B_{\pi e2} provides the most accurate test of lepton universality available. Read More

Precision measurements in neutron beta decay serve to determine the coupling constants of beta decay and allow for several stringent tests of the standard model. This paper discusses the design and the expected performance of the Nab spectrometer. Read More

We present new data for the polarization observables of the final state proton in the $^{1}H(\vec{\gamma},\vec{p})\pi^{0}$ reaction. These data can be used to test predictions based on hadron helicity conservation (HHC) and perturbative QCD (pQCD). These data have both small statistical and systematic uncertainties, and were obtained with beam energies between 1. Read More

2010Dec

Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton electric to magnetic form factor ratio, $G_{E}/G_{M}$, obtained separately from cross section and polarization transfer measurements. One possible explanation for this difference is a two-photon-exchange (TPEX) contribution. In an effort to search for effects beyond the one-photon-exchange or Born approximation, we report measurements of polarization transfer observables in the elastic $H(\vec{e},e'\vec{p})$ reaction for three different beam energies at a fixed squared momentum transfer $Q^2 = 2. Read More

2010May

Among the most fundamental observables of nucleon structure, electromagnetic form factors are a crucial benchmark for modern calculations describing the strong interaction dynamics of the nucleon's quark constituents; indeed, recent proton data have attracted intense theoretical interest. In this letter, we report new measurements of the proton electromagnetic form factor ratio using the recoil polarization method, at momentum transfers Q2=5.2, 6. Read More

A new measurement of $B_{\pi e2}$, the $\pi^+ \to e^+\nu(\gamma)$ decay branching ratio, is currently under way at the Paul Scherrer Institute. The present experimental result on $B_{\pi e2}$ constitutes the most accurate test of lepton universality available. The accuracy, however, still lags behind the theoretical precision by over an order of magnitude. Read More

A new measurement of $B_{\pi e2}$, the $\pi^+ \to e^+\nu(\gamma)$ decay branching ratio, is currently under way at the Paul Scherrer Institute. The present experimental result on $B_{\pi e2}$ constitutes the most accurate test of lepton universality available. The accuracy, however, still lags behind the theoretical precision by over an order of magnitude. Read More

The PEN Collaboration is conducting a new measurement of the pi+ -> e+ nu branching ratio at the Paul Scherrer Institute, with the goal uncertainty of delta B/B(pie2)=5E-4 or lower. At present, the combined accuracy of all published pie2 decay measurements lags behind the theoretical calculation by a factor of 40. In this contribution we report on the PEN detector configuration and its performance during two development runs done in 2007 and 2008. Read More

2008Nov
Affiliations: 1nee Rohe, 2nee Rohe, 3nee Rohe, 4nee Rohe, 5nee Rohe, 6nee Rohe, 7nee Rohe, 8nee Rohe, 9nee Rohe, 10nee Rohe, 11nee Rohe, 12nee Rohe, 13nee Rohe, 14nee Rohe, 15nee Rohe, 16nee Rohe, 17nee Rohe, 18nee Rohe, 19nee Rohe, 20nee Rohe, 21nee Rohe, 22nee Rohe, 23nee Rohe, 24nee Rohe, 25nee Rohe, 26nee Rohe, 27nee Rohe, 28nee Rohe, 29nee Rohe, 30nee Rohe, 31nee Rohe, 32nee Rohe, 33nee Rohe, 34nee Rohe, 35nee Rohe, 36nee Rohe, 37nee Rohe, 38nee Rohe, 39nee Rohe, 40nee Rohe, 41nee Rohe, 42nee Rohe, 43nee Rohe, 44nee Rohe, 45nee Rohe, 46nee Rohe, 47nee Rohe, 48nee Rohe, 49nee Rohe, 50nee Rohe, 51nee Rohe, 52nee Rohe

We have extracted QCD matrix elements from our data on double polarized inelastic scattering of electrons on nuclei. We find the higher twist matrix element \tilde{d_2}, which arises strictly from quark- gluon interactions, to be unambiguously non zero. The data also reveal an isospin dependence of higher twist effects if we assume that the Burkhardt-Cottingham Sum rule is valid. Read More

The Nab collaboration will perform a precise measurement of 'a', the electron-neutrino correlation parameter, and 'b', the Fierz interference term in neutron beta decay, in the Fundamental Neutron Physics Beamline at the SNS, using a novel electric/magnetic field spectrometer and detector design. The experiment is aiming at the 10^{-3} accuracy level in (Delta a)/a, and will provide an independent measurement of lambda = G_A/G_V, the ratio of axial-vector to vector coupling constants of the nucleon. Nab also plans to perform the first ever measurement of 'b' in neutron decay, which will provide an independent limit on the tensor weak coupling. Read More

2008Apr
Affiliations: 1University of Virginia, 2University of Virginia, 3University of Virginia

Segmented electromagnetic calorimeters are used to determine both the total energy and direction (momentum components) of charged particles and photons. A trade off is involved in selecting the degree of segmentation of the calorimeter as the spatial and energy resolutions are affected differently. Increased number of individual detectors reduces accidental particle pile-up per detector but introduces complications related to ADC pedestals and pedestal variations, exacerbates the effects of electronic noise and ground loops, and requires summing and discrimination of multiple analog signals. Read More

We have measured the $\pi^+\to {\rm e}^+\nu\gamma$ branching ratio over a wide region of phase space, based on a total of 65,460 events acquired using the PIBETA detector. Minimum-$\chi^2$ fits to the measured $(E_{e^+},E_\gamma)$ energy distributions result in the weak form factor value of $F_A=0.0119(1)$ with a fixed value of $F_V=0. Read More

2006Aug
Affiliations: 1University of Virginia, 2University of Virginia, 3University of Virginia, 4University of Virginia

Precise calculation of the geometrical acceptance of a large solid angle detector with an integrated stopping target relies on precise knowledge of the beam geometry. We describe four alternative methods that we used to measure the beam stopping distributions in the PIBETA detector active target: (i) light response of segmented target elements to incident beam particles, (ii) back-tracking of charged particles from pi+ and mu+ decays using multi-wire proportional chambers, (iii) volume distribution of the Dalitz decay (pi0->gamma e+e-) event vertices, and (iv) the opening angle distribution of two pi0 photons originating from the beta decay of pi+ at rest. We demonstrate consistent results obtained by these four independent approaches and show how particular beam stopping distributions affect the detector's geometrical acceptance. Read More

2006Jun

The PIBETA collaboration has used a non-magnetic pure CsI calorimeter operating at the Paul Scherrer Institute to collect the world's largest sample of rare pion and muon decays. We have extracted the absolute pi+ -> pi0 e+ nu decay branching ratio with the 0.55 % total uncertainty. Read More

The abBA collaboration proposes to conduct a comprehensive program of precise measurements of neutron $\beta$-decay coefficients $a$ (the correlation between the neutrino momentum and the decay electron momentum), $b$ (the electron energy spectral distortion term), $A$ (the correlation between the neutron spin and the decay electron momentum), and $B$ (the correlation between the neutron spin and the decay neutrino momentum) at a cold neutron beam facility. We have used a GEANT4-based code to simulate the propagation of decay electrons and protons in the electromagnetic spectrometer and study the energy and timing response of a pair of Silicon detectors. We used these results to examine systematic effects and find the uncertainties with which the physics parameters $a$, $b$, $A$, and $B$ can be extracted from an over-determined experimental data set. Read More

Using a large acceptance calorimeter and a stopped pion beam we have made a precise measurement of the rare Pi+ -> Pi0 e+ Nu,(pi_beta) decay branching ratio. We have evaluated the branching ratio by normalizing the number of observed pi_beta decays to the number of observed Pi+ -> e+ Nu, (pi_{e2}) decays. We find the value of Gamma(Pi+ -> Pi0 e+ Nu)/Gamma(total) = [1. Read More

We have studied radiative pion decays Pi+ -> e+ nu gamma in three broad kinematic regions using the PIBETA detector and a stopped pion beam. Based on Dalitz distributions of 42,209 events we have evaluated absolute Pi -> e nu gamma branching ratios in the three regions. Minimum chi^2 fits to the integral and differential (E(e+),E(gamma)) distributions result in the axial-to-vector weak form factor ratio of gamma = F_A/F_V = 0. Read More

We have used the PIBETA detector at the PSI for a precise measurement of rare pion and muon weak decays. We have collected a large statistical sample of (1) pi+ -> e+ nu, (2) pi+ -> pi0 e+ nu, (3) pi+ -> e+ nu gamma, (4) mu+ -> e+ nu nu, and (5) mu+ -> e+ nu nu gamma decays. We have evaluated the absolute branching ratios for these processes by normalizing to the independently measured number of decaying pi+'s (or mu+'s). Read More

We describe the design, construction and performance of the PIBETA detector built for the precise measurement of the branching ratio of pion beta decay, pi+ -> pi0 e+ nu, at the Paul Scherrer Institute. The central part of the detector is a 240-module spherical pure CsI calorimeter covering 3*pi sr solid angle. The calorimeter is supplemented with an active collimator/beam degrader system, an active segmented plastic target, a pair of low-mass cylindrical wire chambers and a 20-element cylindrical plastic scintillator hodoscope. Read More

2002Dec
Affiliations: 1Department of Physics, University of Virginia, Charlottesville, VA, USA, 2Department of Physics, University of Virginia, Charlottesville, VA, USA, 3Department of Physics, University of Virginia, Charlottesville, VA, USA, 4Department of Physics, University of Virginia, Charlottesville, VA, USA

We have examined long term changes in signal amplitude gain, energy resolution and detection efficiency for the active components of the PIBETA detector system. Beam defining plastic scintillation counters were operated in a ~1 MHz stopped $\pi^+$ beam for a period of 297 days, accumulating radiation doses of up to 2 Mrad. Detectors in the charged particle tracking system--a pair of cylindrical multi-wire proportional chambers and a thin plastic scintillation barrel-shaped hodoscope array--were irradiated during the same running period with an average dose of ~40 krad. Read More

2000Sep
Affiliations: 1University of Virginia, 2University of Virginia, 3University of Virginia

We describe a simple procedure for reducing ADC common noise in modular detectors that does not require additional hardware. A method using detector noise groups should work well for modular particle detectors such as segmented electromagnetic calorimeters, plastic scintillator hodoscopes, cathode strip wire chambers, segmented active targets, and the like. We demonstrate a ``second pedestal noise correction'' method by comparing representative ADC pedestal spectra for various elements of the PIBETA detector before and after the applied correction. Read More

2000Jun
Affiliations: 1Department of Physics, University of Virginia, 2Department of Physics, University of Virginia, 3Department of Physics, University of Virginia

We present the program optics that simulates the light response of an arbitrarily shaped scintillation particle detector. Predicted light responses of pure CsI polygonal detectors, plastic scintillator staves, cylindrical plastic target scintillators and a Plexiglas light-distribution plate are illustrated. We demonstrate how different bulk and surface optical properties of a scintillator lead to specific volume and temporal light collection probability distributions. Read More

2000Jun
Affiliations: 1University of Virginia, 2Paul Scherrer Institute, 3Paul Scherrer Institute, 4University of Virginia, 5Paul Scherrer Institute, 6University of Virginia, 7University of Virginia, 8Institute Rudjer Boskovic, 9Paul Scherrer Institute

We have measured scintillation properties of pure CsI crystals used in the shower calorimeter built for a precise determination of the pi+ -> pi0 e+ nu decay rate at the Paul Scherrer Institute (PSI). All 240 individual crystals painted with a special wavelength-shifting solution were examined in a custom-build detection apparatus (RASTA=radioactive source tomography apparatus) that uses a 137Cs radioactive gamma source, cosmic muons and a light emitting diode as complementary probes of the scintillator light response. We have extracted the total light output, axial light collection nonuniformities and timing responses of the individual CsI crystals. Read More

1999May
Affiliations: 1Univ. of Virginia, 2Inst. Rudjer Boskovic, 3Univ. of Virginia, 4Paul Scherrer Inst, 5Paul Scherrer Inst, 6Paul Scherrer Inst, 7Arizona State Univ, 8Tbilisi State Univ, 9Univ. of Virginia, 10Paul Scherrer Inst, 11Univ. of Virginia, 12Univ. of Virginia, 13Inst. Rudjer Boskovic

Scintillation properties of pure CsI crystals used in the shower calorimeter being built for precise determination of the pi+ -> pi0 e+ nu decay rate are reported. Seventy-four individual crystals, polished and wrapped in Teflon foil, were examined in a multiwire drift chamber system specially designed for transmission cosmic muon tomography. Critical elements of the apparatus and reconstruction algorithms enabling measurement of spatial detector optical nonuniformities are described. Read More

We have measured pion single charge exchange differential cross sections on the proton at 27.5 MeV incident $\pi^-$ kinetic energy in the center of momentum angular range between $0^\circ$ and $55^\circ$. The extracted cross sections are compared with predictions of the standard pion-nucleon partial wave analysis and found to be in excellent agreement. Read More

pi-N and pi-pi interactions near threshold are uniquely sensitive to the chiral symmetry breaking part of the strong interaction. The pi-N sigma-term value with its implications for nucleon quark structure and the recent controversy concerning the size of the scalar quark condensate have renewed the experimental interest in these two fundamental systems. We report new differential cross sections for the reaction $pi^-p \to \pi^0n$ at 27. Read More