S. Nagamiya

Composite particle emission in relativistic heavy ion collisions

Abstract Inclusive spectra of d, t, and 3 He have been measured over a wide range of fragment angles and energies. The observed spectra are well reproduced by the “coalescence model” with a coalescence radius p 0 which is independent of beam energies and which decreases as the sizes of the target-projectile combinations increase. The sizes of the interaction regions have been derived from these p 0 values. The experimental cross sections generally deviate from predictions of the firestreak model.

Wide-angle high-energy proton spectra by 800 MeV/A C, Ne, and Ar beams

Abstract Inclusive proton spectra, as well as two-particle correlations, resulting from collisions between energetic nuclei have been measured. Protons associated with large momentum transfers show exponential-type energy distributions having a decay constant about (70–90 MeV)−1. For light-mass targets a strong two-particle correlation has been observed, which is kinematically consistent with quasi-elastic pp scatterings.

One- and two-proton inclusive spectra in 800 MeV proton-nucleus collisions and the mean free path of protons in nuclei☆

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Two-proton correlation measurements in 800 and 400 MeV/nucleon heavy-ion reactions

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Negative Moun Spin Rotation

The possibility of using the muon spin rotation for solid-state studies is discussed. Some preliminary experimental results of negative muon spin rotation experiments related to g-factor measurements in diamagnetic metals and relaxation phenomena in transition metals are presented.

Negative pion production by 800 MeV/A C, Ne, and Ar beams

Abstract Energy and angular distributions of πs produced in relativistic heavy-ion collisions have been measured at 800 MeV/A incident energy. Cross sections for low-energy pions ( E cm ≈ 100–200 MeV) are forward and backward peaked in the nucleon-nucleon c.m. frame. Such anisotropy becomes weaker for higher energy pions. The shape of the energy spectra at θ cm = 90° is approximately exponential. Their slopes are steeper than those observed for protons. The data are discussed in terms of several models.

Total muon captures rates in actinide nuclei

Abstract Lifetimes of negative muons bound to 232 Th, 235 U 238 U and 239 Pu have been determined to be 80.4 ± 2.0 ns ( 232 Th), 78 ± 4 ns( 235 U), 81.5 ± 2.0 ns ( 238 U) and 77.5 ± 2.0 ns( 239 Pu) by observing decay electrons from muons. Systematics of total muon capture rates is discussed. They are also compared with the lifetimes determined by fission fragments in view of possible fission-isomer excitation by muons.

Shape isomer excitation by mu-minus atomic capture?

Abstract The possibility of excitation of the 238 U shape-isomer by the atomic cascade of a negative muon has been investigated by a search for back-decay γ-rays. No candidates for such γ-rays have been found with yields greater than 1% per stopping muon, indicating that the probability of the isomer excitation by muons is less than 3%. The lifetime of a μ − bound to 238 U has been determined from capture γ-rays to be 79.1 ± 0.5 ns, which also set the upper limit of this probability to 7–15%.

Measurements of high pT light fragments at CM 90° in 800 A MEV C + C collisions

Abstract The spectra of high-pT fragments have been measured at CM 90° in 800 A MeV C + C collisions for pT up to 1.8 GeV/c (proton), 2.5 GeV/c (deuteron) and 2.8 GeV/c (triton) at the Bevalac. Invariant cross sections were measured down to eight orders of magnitude lower than those for production of low momentum protons. The proton spectrum shows a significant deviation from the Boltzmann shape in the high-energy region. The spectra of deuterons and tritons are explained well by, respectively, squaring and cubing the observed proton spectra.