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Register a new userDifferential cross sections of the charge-exchange reaction pi- p --> pi0 n in the momentum range from 103 to 178 MeV/c
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Measured values of the differential cross sections for pion-nucleon charge exchange, pi- p --> pi0 n, are presented for pi- momenta of 103, 112, 120, 130, 139, 152, and 178 MeV/c. Complete angular distributions were obtained by using the Crystal Ball detector at the Alternating Gradient Synchrotron at Brookhaven National Laboratory. Statistical uncertainties of the differential cross sections vary from 3% to 6% in the backward angle region, and from 6% to about 20% in the forward region with the exception of the two most forward angles. The systematic uncertainties are estimated to be about 3% for all momenta.
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A high statistics $Sigma p$ scattering experiment has been performed at the J-PARC Hadron Experimental Facility. Data for momentum-tagged $Sigma^{-}$ running in a liquid hydrogen target were accumulated by detecting the $pi^{-}p to K^{+}Sigma^{-}$ reaction with a high intensity $pi^{-}$ beam of 20 M/spill. Differential cross sections of the $Sigma^{-}p$ elastic scattering were derived with a drastically improved accuracy by identifying the largest statistics of about 4,500 events from 1.72 $times$ $10^{7}$ $Sigma^{-}$. The derived differential cross section shows a clear forward-peaking angular distribution for a $Sigma^{-}$ momentum range from 470 to 850 MeV/$c$. The accurate data will impose a strong constraint on the theoretical models of the baryon-baryon interactions.
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.
We report a measurement of the differential cross section for the $gamma n to pi^- p$ process from the CLAS detector at Jefferson Lab in Hall B for photon energies between 1.0 and 3.5 GeV and pion center-of-mass (c.m.) angles ($theta_{c.m.}$) between 50$^circ$ and 115$^circ$. We confirm a previous indication of a broad enhancement around a c.m. energy ($sqrt{s}$) of 2.2 GeV at $theta_{c.m.}=90^circ$ in the scaled differential cross section, $s^7 {frac{dsigma}{dt}}$. Our data show the angular dependence of this enhancement as the scaling region is approached in the kinematic region from 70$^circ$ to 105$^circ$.
Differential cross sections for pi- p and pi+ p elastic scattering were measured at five energies between 19.9 and 43.3 MeV. The use of the CHAOS magnetic spectrometer at TRIUMF, supplemented by a range telescope for muon background suppression, provided simultaneous coverage of a large part of the full angular range, thus allowing very precise relative cross section measurements. The absolute normalisation was determined with a typical accuracy of 5 %. This was verified in a simultaneous measurement of muon proton elastic scattering. The measured cross sections show some deviations from phase shift analysis predictions, in particular at large angles and low energies. From the new data we determine the real part of the isospin forward scattering amplitude.
Differential and angle-integrated cross sections for the $^{10}$B($n, {alpha}$)$^{7}$Li, $^{10}$B($n, {alpha}$$_{0}$)$^{7}$Li and $^{10}$B($n, {alpha}$$_{1}$)$^{7}$Li$^{*}$ reactions have been measured at CSNS Back-n white neutron source. Two enriched (90%) $^{10}$B samples 5.0 cm in diameter and ~85.0 ${mu}$g/cm$^{2}$ in thickness each with an aluminum backing were prepared, and back-to-back mounted at the sample holder. The charged particles were detected using the silicon-detector array of the Light-charged Particle Detector Array (LPDA) system. The neutron energy E$_{n}$ was determined by TOF (time-of-flight) method, and the valid ${alpha}$ events were extracted from the E$_{n}$-Amplitude two-dimensional spectrum. With 15 silicon detectors, the differential cross sections of ${alpha}$-particles were measured from 19.2{deg} to 160.8{deg}. Fitted with the Legendre polynomial series, the ($n, {alpha}$) cross sections were obtained through integration. The absolute cross sections were normalized using the standard cross sections of the $^{10}$B($n, {alpha}$)$^{7}$Li reaction in the 0.3 - 0.5 MeV neutron energy region. The measurement neutron energy range for the $^{10}$B($n, {alpha}$)$^{7}$Li reaction is 1.0 eV $le$ En < 2.5 MeV (67 energy points), and for the $^{10}$B($n, {alpha}$$_{0}$)$^{7}$Li and $^{10}$B($n, {alpha}$$_{1}$)$^{7}$Li$^{*}$ reactions is 1.0 eV $le$ En < 1.0 MeV (59 energy points). The present results have been analyzed by the resonance reaction mechanism and the level structure of the $^{11}$B compound system, and compared with existing measurements and evaluations.
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