Gamma-ray spectroscopy with relativistic exotic heavy-ions

Feasibility of gamma-ray spectroscopy at relativistic energies with exotic heavy-ions and new generation of germanium detectors (segmented Clover) is discussed. An experiment with such detector array and radioactive is discussed.     

Spontaneous ternary fission of 252Cf: New experiment with GSI super clover detectors

A new multiparameter experiment on ternary fission of ²⁵²Cf has recently been successfully performed by using the CODIS2 detector system and two GSI segmented Super Clover Ge γ-ray detectors. The experimental setup and the main subjects of interest are briefly described.     

Elemental Analysis of Engine Parts of the Proton Rocket Carrier with Resonance Neutrons

At the JINR Laboratory of Nuclear Physics, neutron–nucleus interactions are investigated for fundamental and applied purposes using the IREN pulsed neutron source. The applied research includes an elemental analysis of constituent materials of various devices. This paper describes the elemental-analysis techniques employed and reports the measurement of palladium abundances in the engine components of the Proton rocket carrier. The elemental-analysis technique involving resonance neutrons, currently implemented with the Romashka apparatus, is shown to be sensitive to palladium abundances at a level of 2 mg/g for samples with masses on the order of 60 g. Further developing the method will boost its sensitivity and allow for elemental analyses of larger samples and their assemblies.     

A new μs isomer in 136Sb produced in the projectile fission of 238U

Rapidity correlations in 800 GeV proton interactions with emulsion nuclei are investigated for different targets and multiplicity regions. To study the energy dependence, the results have been compared with proton interactions at 200 GeV and 400 GeV. A common feature of all the interactions is the existence of strong, short-range correlations. However, no dependence of cluster parameters on primary energy or target mass is found. A marginal increase of correlation strength with multiplicity is observed. Received: 30 March 2001 / Accepted: 18 September 2001     

Recent experimental studies on 252Cf ternary fission

The rare ternary fission (TF) process was hitherto studied mainly by inclusive measurements of the energies and fractional yields of the light charged particles (LCPs) from fission, or by experiments on the angular and energy correlation between LCPs and fission fragments (FF). The present article briefly describes a series of recent correlation measurements on ²⁵²Cf(sf) TF that include either the registration of neutrons and γ rays with LCPs and FFs, or the coincident registration of two LCPs. The population of excited states in LCPs has been identified, as well as the formation of neutron-unstable nuclei as short-lived intermediated LCPs, the sequential decay of particle-unstable LCP species into charged particle pairs, and “quaternary” fission with the emission of two charged particles right at scission.     

Cross section calculation of (n,p) and (n,2n) nuclear reactions on Zn,Mo and Pb isotopes with ~ 14 MeV neutrons

Journal of Radioanalytical and Nuclear Chemistry - In this article, we are presenting the results of model calculations for (n,p) and (n,2n) reaction cross sections using the standard nuclear...     

New experimental studies on the quaternary fission of <Superscript>233, 235</Superscript>U(n<Subscript>th</Subscript>, f ) and <Superscript>252</Superscript>Cf (sf )

Experiments have been performed for studying quaternary fission (QF) in spontaneous fission of ²⁵²Cf, on the one hand, and for the neutron-induced fission reactions ^{233, 235}U(n_th, f ), on the other hand. In this higher-multiplicity fission mode, by definition, four charged products appear in the final state. In other words, as a generalization of the ternary-fission process, not only one but two light charged particles (LCPs) are accompanying the splitting of an actinide nucleus into the customary pair of fission fragments. In the two sets of measurements, which have used quite different approaches, the yields of several QF reactions with α-particles and tritons as the LCPs have been determined and the corresponding kinetic-energy distributions of the α-particles measured. The QF process can appear in two basically different ways: i) the simultaneous creation of two LCPs in the act of fission (“true” QF) and ii) via a fast sequential decay of a single but particle-unstable LCP in common ternary fission (“pseudo” QF). Experimentally the two varieties of QF have been distinguished by exploiting the different patterns of angular correlations between the two outgoing LCPs. The experiments described in the present paper are the first to demonstrate that both types of reactions, true and pseudo QF, occur with quite comparable probabilities. As a new result also, the kinetic-energy distributions related to the two processes have been shown to be significantly different. For all QF reactions which could be explored, the yields for ²⁵²Cf(sf) were found to be roughly by an order of magnitude larger than the yields found in the ²³³U(n_th, f ) and ²³⁵U(n_th, f ) reactions. An interesting by-product has been the measurement of yields of excited LCPs which allows to deduce nuclear temperatures at scission by comparison to the respective yields in the ground state.     

Measurement of the Yield and Angular Distributions of Gamma Rays Originating from the Interaction of 14.1-MeV Neutrons with Chromium Nuclei

Physics of Atomic Nuclei - The reaction induced by the inelastic scattering of 14.1-MeV neutrons on chromium nuclei is studied by means of the tagged-neutron method at the TANGRA (TAgged Neutrons...