Bruce Cork

Bio: Bruce Cork is an academic researcher from University of California, Berkeley. The author has contributed to research in topics: Elastic scattering & Proton. The author has an hindex of 14, co-authored 36 publications receiving 784 citations.

Momentum distributions of isotopes produced by fragmentation of relativistic C-12 and O-16 projectiles

Abstract: The fragment momentum distributions in the projectile rest frame are, typically, Gaussian shaped, narrow, consistent with isotropy, depend on fragment and projectile, and have no significant correlation with target mass or beam energy. The nuclear temperature is inferred from the momentum distributions of the fragments and is approximately equal to the projectile nuclear binding energy, indicative of small energy transfer between target and fragment.

K - -p and K - -n Cross Sections in the Momentum Range 1-4 Bev/c

Abstract: The energy dependence of the ${K}^{\ensuremath{-}}$-nucleon total cross sections has been measured over the ${K}^{\ensuremath{-}}$ momentum range 0.98-3.98 Bev/c. ${K}^{\ensuremath{-}}\ensuremath{-}n$ cross sections were obtained by deuterium-hydrogen subtraction, with a correction for screening effects. There is evidence for structure in the $T=0$ ${K}^{\ensuremath{-}}$-nucleon state in the momentum range 0.98-2.0 Bev/c. This structure is absent in the $T=1$ state. In addition, a measurement was made at 1.95 Bev/c of the angular distribution of the ${K}^{\ensuremath{-}}\ensuremath{-}p$ elastic scattering at small angles. The forward-scattering amplitude obtained from the data gives a ratio of real part to imaginary part 0.5\ifmmode\pm\else\textpm\fi{}0.2 at ${0}^{0}$. The corresponding ratio for ${\ensuremath{\pi}}^{\ensuremath{-}}$ mesons at this momentum was found to be ${0.4}_{\ensuremath{-}0.4}^{+0.2}$.

ANTIPROTON-PROTON CROSS SECTIONS AT 133, 197, 265, AND 333 Mev

Abstract: In a scintillation-counter experiment the interaction of antiprotons with protons in the energy region 133 to 333 Mev has been studied. Antiprotons, produced internally in the Bevatron, channeled externally by a system of magnetic quadrupoles and bending magnets, and identified by time of flight, entered a target containing liquid hydrogen. This target was completely surrounded by a system of scintillation counters which detected both scattered antiprotons and annihilation secondaries. An electrostatic-magnetic velocity spectrometer was used in the external magnetic channel to increase the ratio of antiprotons to pions. The $\overline{p}\ensuremath{-}p$ total, elastic, inelastic, and charge-exchange cross sections, and the angular distribution of elastic scattering were measured at each energy. The inelastic cross section is approximately one-half the total cross section at these energies. The results are discussed in connection with current theories.

Nucleon Isobar Production in Proton-Proton Collisions between 3 and 7 GeV c

Abstract: A systematic study has been made of the reactions $\mathrm{pp}\ensuremath{\rightarrow}\mathrm{pp}$ and $\mathrm{pp}\ensuremath{\rightarrow}p{N}^{*}$ in the angular range from ${\ensuremath{\theta}}_{\mathrm{lab}}={10}^{\ensuremath{\circ}}$ to ${\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}={90}^{\ensuremath{\circ}}$ at 3, 4, 5, 6, and 7 $\frac{\mathrm{GeV}}{c}$. An orthogonal dispersion magnetic spectrometer detected protons from interactions in hydrogen with momentum transfer ($\ensuremath{-}t$) in excess of 0.5 ${(\mathrm{GeV})}^{2}$. Well-defined peaks in the missing-mass spectra occurred at average ${N}^{*}$ masses of 1240\ifmmode\pm\else\textpm\fi{}6, 1508\ifmmode\pm\else\textpm\fi{}2, and 1683\ifmmode\pm\else\textpm\fi{}3 MeV with average full widths of 102\ifmmode\pm\else\textpm\fi{}4, 92\ifmmode\pm\else\textpm\fi{}3, and 110\ifmmode\pm\else\textpm\fi{}4 MeV, respectively. Below 2400 MeV no other significant enhancements were found. The ${N}^{*}$ production cross sections $\frac{d\ensuremath{\sigma}}{\mathrm{dt}}$ near ${\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}={90}^{\ensuremath{\circ}}$ are in qualitative agreement with the predictions of the statistical model. For each isobar the differential cross section at fixed energy varies as $\mathrm{exp}(\ensuremath{-}\frac{v}{{v}_{0}})$, where $v\ensuremath{\equiv}[\ensuremath{-}\frac{\mathrm{tu}}{(t+u)}]$; ${v}_{0}$ varies systematically with energy and tends toward the same value ($\ensuremath{\approx}0.4$ Ge${\mathrm{V}}^{2}$) for each isobar at the upper limit of our energy range.

Theoretical and experimental aspects of the energy loss of relativistic heavily ionizing particles

Abstract: We review the theory of the electromagnetic interactions between rapidly moving charged particles and the matter through which they pass. The emphasis will be on very massive electric ($\ensuremath{-}100\ensuremath{\le}{Z}_{1}100$) and magnetic ($|g|=137e \mathrm{and} \frac{137e}{2}$) particles moving with relativistic velocities ($\ensuremath{\beta}g0.2$, $\ensuremath{\gamma}l100$). Consideration will be given to both the stopping power of the projectile and to the response of the absorbing medium to the excitation caused by the projectile.

Antiproton Flux, Antiproton-to-Proton Flux Ratio, and Properties of Elementary Particle Fluxes in Primary Cosmic Rays Measured with the Alpha Magnetic Spectrometer on the International Space Station

Abstract: A precision measurement by AMS of the antiproton flux and the antiproton-to-proton flux ratio in primary cosmic rays in the absolute rigidity range from 1 to 450 GV is presented based on 3.49 × 105 antiproton events and 2.42 × 109 proton events. The fluxes and flux ratios of charged elementary particles in cosmic rays are also presented. In the absolute rigidity range ∼60 to ∼500 GV, the antiproton ¯p, proton p, and positron eþ fluxes are found to have nearly identical rigidity dependence and the electron e− flux exhibits a different rigidity dependence. Below 60 GV, the ( ¯ p=p), ( ¯ p=eþ), and (p=eþ) flux ratios each reaches a maximum. From ∼60 to ∼500 GV, the ( ¯ p=p), ( ¯ p=eþ), and (p=eþ) flux ratios show no rigidity dependence. These are new observations of the properties of elementary particles in the cosmos.

Transport Methods and Interactions for Space Radiations

Abstract: A review of the program in space-radiation protection at the Langley Research Center is given. The relevant Boltzmann equations are given with a discussion of approximation procedures for space applications. The interaction coefficients are related to the solution of the many-body Schrodinger equations with nuclear and electromagnetic forces. Various solution techniques are discussed to obtain relevant interaction cross sections with extensive comparison with experiments. Solution techniques for the Boltzmann equations are discussed in detail. Transport computer code validation is discussed through analytical benchmarking, comparison with other codes, comparison with laboratory experiments, and measurements in space. Applications to missions to the Moon and Mars are discussed.