Peter Lipnik

Measurement of small-angle antiproton-proton and proton-proton elastic scattering at the CERN intersecting storage rings☆

Abstract Antiproton-proton and proton-proton small-angle elastic scattering was measured for centre-of-mass energies s =30.6, 52.8 and 62.3 GeV at the CERN Intersectung Storage Rings. In addition, proton-proton elastic scattering was measured at s =23.5 GeV . Using the optical theorem, total cross sections are obtained with an accuracy of about 0.5% for proton-proton scattering and about 1% for antiproton-proton scattering. The measurement of the interference of the Coulomb scattering and the hadronic scattering permits a determination of the ratio of the real-to-imaginary part of the forward hadronic scattering amplitude. Also presented are measurements of the hadronic slope parameter.

An experimental test of the analogy between muon and radiative pion capture

Abstract Rate-measurements are reported on muon capture and radiative pion capture reactions in 6 Li yielding the ground state of 6 He.

A Novel Design for a Fast Intense Neutron Beam

Abstract A novel design for the production of fast (40−75 MeV) and intense monokinetic neutron beam from the Li(p,n) reaction is described. The primary charged beam is dumped in a Faraday cup immediately behind the Li target. Both the production target and Faraday cup are enclosed inside a compact shielding. With respect to the conventional method where the primary beam is deflected, the advantage of this design is twofold: the neutron beam intensity is enhanced and the background is decreased. The properties of this neutron beam, i.e. its intesity, time width and spatial profile are reported.

Hyperfine effect in the MU - mesonic 11B atom and information on 11Be from muon capture measurements

Abstract The partial rates in the capture of muons by 11B were measured for the ground state and first excited level of 11Be. The transition between the hyperfine states of the μ-+11B mesonic atom was observed indirectly. The 320 keV γ-ray in 11Be, which follws the capture of the muon in 11B, was found to be broadened. Nuclear structure informations were obtained on the ground state and first excited state of 11Be.

Identification of Different Reaction Channels of High-energy Neutrons in Liquid Scintillators By the Pulse-shape Discrimination Method

A study of the n-gamma discrimination with NE213 and BC501A liquid scintillators, carried out with 40 and 56 MeV neutron beams, reflects different reaction channels involved in the detection process of high energy neutrons. Up to seven different reaction channels were identified in the pulse shape discrimination spectrum measured by a digital charge comparison method. The analysis of the energy spectra of the secondary particles allowed the cross sections for different reaction channels to be estimated as well. This is shown for the important C-12(n, d) reaction and the non-negligible contribution of the C-12(n, t) reaction to the total efficiency of the NE 213 liquid scintillator for neutrons.

A method to measure neutrino-gamma angular correlation in muon-capture

Abstract We consider the Doppler-broadening of the gamma-ray emitted by a bound-state excited in muon-capture in complex nuclei. This Doppler-broadened gamma spectrum is illustrated for special cases assuming realistic neutrino-gamma directional correlations and taking into account the finite energy-resolution of the Ge(Li) detector. It appears that the observation of the Doppler-broadened deexcitation gamma-ray spectrum offers a practical method to measure the neutrino-gamma directional correlation in muon-capture reactions.

COMPARISON OF p anti-p AND p p ELASTIC SCATTERING AT S**(1/2) = 52.8-GeV

Abstract Proton-antiproton and proton-proton elastic scattering have been measured in the four-momentum transfer range 0.001⩽| t |⩽0.06 GeV 2 for center-of-mass energy 52.8 GeV at the CERN Intersecting Storage Rings (ISR). Using the known pp total cross section, a simultaneous fit to the pp and pp differential cross sections yields the pp total cross section; in addition, we obtain the ratio of the real-to-imaginary part of the forward nuclear-scattering amplitude and the nuclear-slope parameter for both pp and pp. Our results show conclusively that the pp total cross section is rising at ISR energies and lend support to conventional theories in which the difference between the pp and pp total cross section vanishes at very high energy.

Measurement of the total cross section for the /sup 1/H(n, gamma )/sup 2/H reaction between 37 and 72 MeV

The total cross section for radiative neutron-proton capture has been measured at 37, 42, 47, 52, 63 and 73 MeV. The inverse process, the photodisintegration of the deuteron, was measured in the same energy range by different authors with contradictory results, some of them in large disagreement with all theoretical predictions of the cross section. The submitted data are in agreement with theory and the results of a recent total absorption experiment.

Total cross section for the H(n, d)γ reaction between 45 and 70 MeV

Abstract The total cross section for neutron-proton capture was measured between 45 and 70 MeV neutron energy. The results, which were normalized to the neutron-proton differential cross section at 90† center-of-mass, were found to be in agreement with a global fit of the photodisintegration data, but in slight disagreement with potential model calculations.

COMPARISON OF SMALL ANGLE p anti-p AND p p ELASTIC SCATTERING AT THE CERN INTERSECTING STORAGE RINGS

Abstract Antiproton-proton and proton-proton small-angle elastic scattering have been measured for centre-of-mass energies √ s = 30.7 and 62.5 GeV at the CERN Intersecting Storage Rings (ISR). Antiproton-proton and proton-proton total cross sections are obtained using the optical theorem. The measurement of the Coulomb scattering and its interference with the nuclear scattering allows a determination of the ratio of the real-to-imaginary part of the forward nuclear scattering amplitude. Also presented are measurements for the nuclear slope parameter at √ s = 62.5 GeV. Our new results reinforce the conclusions drawn recently from our measurements at √ s = 52.8 GeV. In particular, the pp total cross section is rising at ISR energies and should continue to rise well beyond these energies.