Inclusive pion production by pions on nuclei and determination of root-mean-square radii of proton and neutron distributions

A brief nonanalytic survey of data available in the literature for parameters that characterize nuclear sizes is given, and the potentials of some methods for determining these sizes are compared. Attention is given primarily to determining nuclear sizes in experiments that study pion-nucleus interaction. For pointlike protons and neutrons, values of parameters that describe the radial dependences of their densities according to the Fermi distribution are presented in a tabular form. The method proposed previously at the Institute of Theoretical and Experimental Physics (ITEP, Moscow) for determining nuclear sizes on the basis of measuring differential cross sections for π^? + A → π _forw ^± + X processes in the kinematical region where the recorded interaction event occurs on a single proton (neutron) of nucleus A, the presence of the remaining nucleons manifesting itself in shadowing effects, is described, and examples of the application of this method are given.     

Neutron detection using a crystal ball calorimeter

The program of experiments of the A2 Collaboration performed on a beam of tagged photons of the MAMI electron microtron in Mainz (Germany) includes precision measurements of the total and differential cross sections of the pion photoproduction on neutrons of a deuterium target. The determination of the detector ability to detect neutrons is undoubtedly one of the important problems of the experiment. The calorimetric system of the detector contains a segmented NaI Crystal Ball detector, which gives information about the position, energy, and detection time of neutral and charged particles in a wide angular range. In this work, we describe the measurement of the neutron detection efficiency in the energy range from 20 to 400MeV. The results are compared with BNL data obtained on a pion beam and proton target.     

Spectra of fast π + mesons from the π − A → π + X reaction on oxygen and lithium nuclei at 0.59 GeV

The spectra of fast π ⁺ mesons from the π ^? A → π ⁺ X reaction on A=⁶Li, ⁷Li, and ¹⁶O nuclei at a primary momentum of p ₀=0.72 GeV/c (T ₀=0.59 GeV) are measured at emission-angle values in the range ?=0°–14°. The results obtained in this way are compared with experimental data taken in other studies at lower energies and with the results of model calculations. The energy dependence of the cross sections and of shadowing effects is analyzed for the reactions in question that occur on lithium isotopes.     

Results of search for narrow diproton structures in thepn →ppπ − reaction at 1.98 GeV/c

The effective mass spectrum of two protons from the reactionp+n→pp+π ^?(backward) was investigated. The work was carried out at ITEP using a 3-meter magnet spectrometer and a proton beam of 1.98GeV/c momentum. Liquid deuterium was used as a target. The presented mass spectrum includes about 34000 events. No statistically significant signals from narrow dibaryons were found in the mass region 1.89–2.17GeV/c ²; the upper limits on narrow dibaryon production cross-section are given. At a mass of 1.8775GeV/c ² a narrow enhancement was found. A more detailed investigation of the observed phenomenon is needed.     

Cumulative $${\pi}$$ -Mesons in $${}^{{12}}{C}{+}{}^{{9}}$$ Be-Interactions at 3.2 GeV/Nucleon

Physics of Atomic Nuclei - In the FRAGM experiment at the heavy-ion accelerator $$-$$ accumulator complex ITEP $$-$$ TWA, yields of cumulative charged $$\pi$$ mesons have been measured in a...     

Light fragments in (C + Be) interaction at an energy of 300 MeV/nucleon

Spectra of light fragments from carbon ion fragmentation at an energy of 0.3 GeV/nucleon on a beryllium target were measured at an angle of 3.5°. The fragment spectra covered both the evaporation and cumulative regions to higher energies than in previous experiments. The spectrum slope parameters characterizing the temperature of expanding matter in these regions were determined for protons and deuterons.     

Nuclear Fragments in the Interactions of Carbon Nuclei with a Beryllium Target at the Energy of 0.95 GeV per Nucleon

The differential cross sections for the yields of nuclear fragments at an angle of 3.5? in the fragmentation of carbon nuclei with energy 0.95 GeV per nucleon on a beryllium target were measured in the FRAGM experiment at the ITEP TWA heavy-ion accelerator. The momentum spectra of fragments were used to test the following four models of ion–ion interactions: BC, INCL++, LAQGSM03.03, and QMD. For light fragments, the slope parameters of the kinetic-energy spectra were obtained in the cumulative region.     

Yields of hydrogen and helium isotopes in fragmentation of carbon ions with the energy of 0.3 GeV/nucleon

Data on the yields of hydrogen isotopes (p, d, t) and helium isotopes (from ³He to ⁸He) at the angle of 3.5° in fragmentation of the carbon ions with the energy of 0.3 GeV/nucleon on the beryllium target are reported. The momentum spectra of the fragments in the rest frame of the fragmenting nucleus are measured in a considerably larger momentum range than in the previous experiments.     

Temperature parameters in the fragmentation of carbon ions at the energy of 0.6 GeV/nucleon

Momentum distributions of nuclear fragments at an angle of 3.5° in the interaction of 0.6-GeV/nucleon carbon ions with a beryllium target are measured in the FRAGM experiment on the ITEP-TWAC facility. The measured spectra are used for testing predictions of four ion–ion interaction models: BC, QMD, INCL, and LAQGSM03.03, and for comparison with the analytical parameterization within the thermodynamic concept of fragmentation.     

Production of the neutron-rich hypernucleus 10LambdaLi in the (pi-,K+) double charge-exchange reaction

In order to produce a neutron-rich Lambda hypernucleus for the first time, we carried out an experiment by utilizing the (pi-,K+) double charge-exchange reaction on a 10B target. We observed the production of a 10LambdaLi hypernucleus. The cross section for the Lambda bound region was found to be 11.3+/-1.9 nb/sr with the 1.2 GeV/c incident momentum, which is compared with the 10LambdaB hypernucleus production cross section, 7.8+/-0.3 microb/sr, in the (pi+,K+) reaction with a 1.05 GeV/c incident momentum beam.