Multiplicities in84Kr interactions in emulsion at 800–950 MeV/nucleon

Inelastic interactions induced by⁸⁴Kr nuclei at 800–950 MeV/nucleon have been studied using a high angular resolution emulsion detector. Data on multiplicities of the produced particles, projectile and target fragments are shown. Comparisons with cascade calculations have been performed.We thank to Swedish Research Council for Natural Sciences for the financial support. Scanning and measurements performed by E.G. Broomé and V. Kopljar are acknowledged.     

Breakup effects of 6,7li on elastic and inelastic scattering from 12C at 18–28 MeV/nucleon

The differential cross sections for elastic scattering of ^6,7Li from ¹²C and inelastic one from the lowest three excited states of ¹²C have been measured at bombarding energies of 18–28 MeV/nucleon. Theoretical analyses of the data have been performed in which consistent treatments of density distributions for the ground and excited states of both projectile and target nuclei are made in the framework of microscopic cluster models for ^6,7Li and ¹²C and projectile-target interactions are generated by the double folding of the M3Y effective nucleon-nucleon interaction. About 25% reduction of the real part of folded potentials is required both in the analyses of elastic scattering with the single-channel calculation and in those of inelastic scattering with the coupled-channel calculation including the excited states of ¹²C. This reduction can be explained as a projectile breakup effect on elastic and inelastic scattering in comparison with a coupled-discretized-continuum-channels (CDCC) calculation and an extended CDCC one which allows mutual excitations of both projectile and target nuclei for ⁶Li case, respectively. It is also seen that an effect due to the target excitation on elastic scattering is of less importance than that of the ^6,7Li projectile breakup processes even fora deformed nucleus like ¹²C. Discrepancy between the extended CDCC calculation and inelastic data for the 0⁺₂ state of ¹²C suggests a strong influence from the ¹²C → 3α breakup channels in the ⁶Li case.     

Model-independent data reductions of elastic proton–proton scattering

New developments in empirical analyses of the proton–proton differential cross section data at high energies are reported. Making use of an unconstrained model-independent parametrization for the scattering amplitude and two different fit procedures, all the experimental data in the center-of-mass energy interval 19.4–62.5 GeV are quite well described (optical point and data above the region of Coulomb-nuclear interference). The contributions from the real and imaginary parts of the amplitude beyond the forward direction are discussed and compared with the results from previous analyses and phenomenological models. Extracted overlap functions (impact parameter space) are outlined and a critical discussion on model-independent analyses and results are also presented.     

Strangeness in the nucleon: neutrino–nucleon and polarized electron–nucleon scattering

After the EMC and subsequent experiments at CERN, SLAC and DESY on the deep inelastic scattering of polarized leptons on polarized nucleons, it is now established that the Q²=0 value of the axial strange form factor of the nucleon, a quantity which is connected with the spin of the proton and is quite relevant from the theoretical point of view, is relatively large.In this review, we consider different methods and observables that allow one to obtain information on the strange axial and vector form factors of the nucleon at different values of Q². These methods are based on the investigation of the neutral current induced effects such as the P-odd asymmetry in the scattering of polarized electrons on protons and nuclei, the elastic neutrino (antineutrino) scattering on protons and the quasi-elastic neutrino (antineutrino) scattering on nuclei. We discuss in detail the phenomenology of these processes and the existing experimental data.     

Proposal for the Simultaneous Measurement of the Neutron–Neutron and Neutron–Proton Quasi-Free Scattering Cross Section via the Neutron–Deuteron Breakup Reaction at E n = 19 MeV

In order to confirm or refute the present discrepancy between data and calculation for the neutron–neutron quasi-free scattering cross section in the neutron–deuteron breakup reaction, we describe a new experimental approach currently being pursued at TUNL.     

Data on the Neutron–Neutron Scattering Length from the nd-Breakup Reaction at En = 8 MeV and En = 11 MeV

Physics of Atomic Nuclei - A kinematically complete experiment devoted to studying the $$nd$$ -breakup reaction at energies of 8 and 11 MeV via detecting all three secondary particles was...     

Neutron–Deuteron Scattering Observables at E lab = 14.1 MeV

Inelastic neutron–deuteron scattering is studied on the basis of configuration-space Faddeev equations. Calculated are neutron–deuteron breakup amplitudes using AV14 nucleon–nucleon potential at incident neutron energy of 14.1 MeV. The results of calculations are presented for the differential cross sections under quasi free scattering and space–star configurations, and compared with those of the previous calculations and experimental data. The choice of the cutoff radius R _cutoff for asymptotic conditions is discussed.     

The effect of nonlinearity in relativistic nucleon–nucleon potential

A simple form for nucleon–nucleon (NN) potential is introduced as an alternative to the popular M3Y form using the relativistic mean field theory (RMFT) with the non-linear terms in σ-meson for the first time. In contrast to the M3Y form, the new interaction becomes exactly zero at a finite distance and the expressions are analogous with the M3Y terms. Further, its applicability is examined by the study of proton and cluster radioactivity by folding it with the RMFT-densities of the cluster and daughter nuclei to obtain the optical potential in the region of proton-rich nuclides just above the double magic core¹⁰⁰Sn. The results obtained were found comparable with the widely used M3Y NN interactions.     

Further Analysis of Neutron Double-Differential Cross Section of n ＋ ^16O at 14.1 MeV and 18 MeV

By using a new reaction model for light nuclei, the double-differential cross section of total outgoing neutron with LUNF code for n＋^16O reactions at En=14.1 MeV and 18 MeV have been calculated and analyzed. In this paper the opened reaction channels, which have contribution to emitting the neutrons, are listed in detail. To improve the fitting results the direct inelastic scattering mechanism is involved. The calculating results agree fairly well with the experimental data at E,~ = 14.1 MeV and the deviation from calculated results and experimental data in low energy region at En= 18 MeV has been analyzed. Since the possibility of 5He has been affirmed theoretically [J.S. Zhang, Sci. Chin. G 47 （2004） 137], so 5He emission from n＋ ^16O reaction is taken into account, which plays an important role at the region of the outgoing neutron energy εn〈3 MeV in total outgoing neutron energy-angular spectrum. The calculated results indicate that the pre-equilibrium mechanism dominates the whole reaction processes, and the recoil effect in light nuclear reactions is essentially important.     

Nuclear-like effects in proton–proton collisions at high energy

We show that several effects considered nuclear effects are not nuclear in the sense that they do not only occur in nucleus–nucleus and hadron–nucleus collisions but, as well, they are present in hadron–hadron (proton–proton) collisions. The matter creation mechanism in hh, hA and AA collision is always the same. The p _T suppression of particles produced in large multiplicity events compared to low multiplicity events, the elliptic flow and the Cronin effect are predicted to occur in pp collisions at LHC energies as a consequence of the high density partonic medium obtained.     

Study of the charge dependence of the pion–nucleon coupling constant on the basis of data on low-energy nucleon–nucleon interactions

The relation between quantities that characterize the pion–nucleon and nucleon–nucleon interactions is studied with allowance for the fact that, at low energies, nuclear forces in nucleon–nucleon systems are mediated predominantly by one-pion exchange. On the basis of the values currently recommended for the low-energy parameters of the proton–proton interaction, the charged pion–nucleon coupling constant is evaluated at g_π²±/4π = 14.55(13). This value is in perfect agreement with the experimental value of g_π²±/4π = 14.52(26) found by the Uppsala Neutron Research Group. At the same time, the value obtained for the charged pion–nucleon coupling constant differs sizably from the value of the pion–nucleon coupling constant for neutral pions, which is g_π² 0/4π = 13.55(13). This is indicative of a substantial charge dependence of the coupling constant.     

Comparison of effect of 5 MeV proton and Co-60 gamma irradiation on silicon NPN rf power transistors and N–channel depletion MOSFETs

NPN transistors and N-channel depletion metal oxide semiconductor field effect transistors (MOSFETs) were irradiated with 5?MeV protons and ⁶⁰Co gamma radiation in the dose ranging from 1?Mrad(Si) to 100?Mrad(Si). The different electrical characteristics of the NPN transistor such as Gummel characteristics, excess base current (ΔI_B), dc current gain (h_FE), transconductance (g_m), displacement damage factor (K) and output characteristics were studied as a function of total dose. The different electrical characteristics of N-channel MOSFETs such as threshold voltage (V_th), density of interface trapped charges (ΔN_it), density of oxide trapped charges (ΔN_ot), transconductance (g_m), mobility (µ) and drain saturation current (I_DSat) were studied systematically before and after irradiation in the same dose ranges. A considerable increase in the base current (I_B) and decrease in the h_FE, g_m and collector saturation current (I_CSat) were observed after irradiation in the case of the NPN transistor. In the N-channel MOSFETs, the ΔN_it and ΔN_ot were found to increase and V_th, g_m, µ and I_DSat were found to decrease with increase in the radiation dose. The 5?MeV proton irradiation results of both the NPN transistor and N-channel MOSFETs were compared with ⁶⁰Co gamma-irradiated devices in the same dose ranges. It was observed that the degradation in 5?MeV proton-irradiated devices is more when compared with the ⁶⁰Co gamma-irradiated devices at higher total doses.     

Pre-equilibrium γ ray emission in different reaction mechanisms at 8 MeV/nucleon

Recent experimental results on particles-γ coincidence measurements on the systems ¹²C +⁶⁴Ni and ³⁵Cl +⁶⁴Ni at about 8 MeV/nucleon are interpreted as due to the effect of a Dipole pre-equilibrium emission produced during the damping of the proton-neutron relative collective motion in very deformed intermediate systems formed in the first instants of the collision. The pre-equilibrium effects are evaluated through semiclassic kinetic theories and through modified statistical approach to include non-stationary effects in Fusion processes, Massive Transfer reactions (in the ¹²C +⁶⁴Ni system) and in Binary Dissipative reactions (in the ³⁵Cl +⁶⁴Ni system). In particular the study performed on the dipole molecular component allows to establish a link between the above phenomenon and the charge and mass transfer process in quasi-peripheral reactions. Received: 15 April 1998 / Revised version: 8 June 1998     

A Monte Carlo generator of nucleon configurations in complex nuclei including nucleon–nucleon correlations

We developed a Monte Carlo event generator for production of nucleon configurations in complex nuclei consistently including effects of nucleon–nucleon (NN) correlations. Our approach is based on the Metropolis search for configurations satisfying essential constraints imposed by short- and long-range NN correlations, guided by the findings of realistic calculations of one- and two-body densities for medium-heavy nuclei. The produced event generator can be used for Monte Carlo (MC) studies of pA and AA collisions. We perform several tests of consistency of the code and comparison with previous models, in the case of high energy proton–nucleus scattering on an event-by-event basis, using nucleus configurations produced by our code and Glauber multiple scattering theory both for the uncorrelated and the correlated configurations; fluctuations of the average number of collisions are shown to be affected considerably by the introduction of NN correlations in the target nucleus. We also use the generator to estimate maximal possible gluon nuclear shadowing in a simple geometric model.