MULTI-2, a 4π spectrometer for total reaction cross section measurements Siváček, I.; Penionzhkevich, Yu.E.; Sobolev, Yu.G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2020, Letnik:
976
Journal Article
Recenzirano
A detection setup for the direct measurement of the total reaction cross section with exotic nuclei is presented. The setup consists of a multi-detector telescope for beam-particle identification and ...a 4π gamma-ray spectrometer for the detection of prompt photons and neutrons accompanying the nuclear reactions. Measurements are based on the modified transmission method and gamma-ray tagging of nuclear reaction events. Registration efficiency and response characteristics of the gamma-ray spectrometer are investigated by Monte Carlo simulations and measurement with 60Co spectroscopic source. Results show strong a dependence of the registration efficiency on gamma-ray multiplicity, with minimum registration efficiency value of 70%. Evaluation of the registration efficiency for data measured in the total reaction cross section experiments is discussed.
The 4π methods used to measure total reaction cross sections σ
R
are presented; they are based on the detection of prompt γ rays and neutrons by scintillation spectrometers with a solid angle Ω close ...to 4π. The experimental setup based on a 12-detector CsI(Tl) spectrometer (Ω = 0.96 × 4π) is described, which has been used in experiments on measuring σ
R
(
E
) for reactions with radioactive isotopes of He, Li, and Be. The above methods and the σ
R
(
E
) measurement results for the
6
He +
28
Si,
59
Co,
181
Ta reactions are analyzed. The advantage of the method allowing for multiplicity of γ rays is shown.
New semiconductor detectors based on CdZnTe and CeBr
3
crystals are tested. A spectrometer facility consisting of CdZnTe, CeBr
3
, and Si (for α–γ measurements) detectors is assembled for ...verification tests. The main parameters of the detectors such as energy resolution FWHM/
E
γ
keV and detection efficiency (%) are investigated and measured. The possibilities of measuring photon radiation in a wide energy range are verified. γ–γ and α–γ coincidences are measured using the detectors. The results of the measurements show that the detectors can be used to study nuclear reactions and properties of reaction products.
Two design options for a heat-recovery turbine unit (HRTU), which generates electricity for self-contained power supply of gas mains’ compressor stations (GMCSs) using the heat of exhaust gases from ...gas-turbine engines (GTEs) driving gas-pumping units (GPUs), are examined. The working fluid of the recovery circuit is octafluorocyclobutane (c-C
4
F
8
, engineering name is RC318) in one of the two HRTUs and the exhaust gases of GPU GTE in the other HRTU. The HRTU operating on RC318 has a three-circuit cycle, including three turbines, three recuperative heat exchangers, three RC318 heaters, and one common condenser. An alternative design of HRTU is a vacuum-type GTU consisting of an overexpansion gas turbine, whose inlet is connected with the exhaust of GPU GTE, exhaust gas coolers, a cooled gas compressor, and an induced-draft fan. The excess power of this HRTU above the current power demand at the GMCS is used to create a vacuum at the exhaust of the gas turbine of the GPU GTE. The results are presented of the comparative balance calculations of parameters and characteristics of both HRTUs as applied to a 16-MW Ural GPU GTE. They were performed using the updated initial data and the software library RefProp (in the CoolProp high-level interface) for the calculation of thermodynamic parameters of working fluids. It has been demonstrated that a more compact and easier to implement gas-type HRTU (with an overexpansion gas turbine), although having a lower power than the RC318-type HRTU, can still fully cover the demand of the GMCS for high-quality power and also to solve the problem of substituting imported gas piston and diesel generators at the GMCS within the shortest possible time and with the lowest capital and operating expenditures.
Two independent methods: Asymptotic Normalization Coefficients (ANC) and Modified Diffraction Model (MDM) were applied to new and existing experimental data to search for states with enhanced radii ...in isobaric analogue states (IAS) of 12B and 12N. The ANC analysis of the 11B(d,p)12B reaction at Ed = 21.5 MeV has confirmed neutron halo existence for two states of 12B: 2−, 1.67 MeV and 1−, 2.62 MeV 1. Some new results were obtained for higher excited states: halo-like states were observed for 0+, 2.72 MeV and 3−, 3.39 MeV states. It should be mentioned that the last one is unbound state, which is 19 keV above the neutron emission threshold and in both states last neutron has a non-zero orbital momentum (ln=1 and ln=2 correspondingly). We propose to use MDM to study isobaric analogue states of 12B in the mirror 12N nucleus and apply it to analyze the (3He,t) reaction data. The existing in the literature data are not completed enough to make definite conclusion about halo in the 2− and 1− states of 12N. This fact simulated us to carry out a new experiment on the 12C(3He,t)12N reaction at the end of 2018. The measurements were conducted at the University of Jyväskylä (Finland) using the K130 cyclotron to produce a 3He beam at E(3He)=40 MeV. The differential cross sections of the 12C(3He,t)12N reaction were measured in the c.m. angular range 8°-70°. Preliminary results for angular distributions are obtained. MDM analysis of preliminary (3He,t) experimental data is done.
The energy dependence of the total cross sections for the sup.6He + Si and sup.9Li + Si reactions was measured at beam energies between 5 and 20 MeV per nucleon. The results agree with experimental ...data published for the sup.6He + Si reaction. New data are obtained for the sup.9Li + Si reaction in the vicinity of a local enhancement of the total cross section. A theoretical analysis of the possible reasons behind the appearance of this peculiarity in the case of collisions of sup.6He and sup.9Li nuclei with silicon target nuclei is performed. In particular, the enhancement may owe its origin to the effect of loosely bound projectile nucleons. DOI: 10.1134/S1063778817050210
The paper presents the results of measurement of the total cross sections for reactions 4,6He+Si and 6,7,9Li+Si in the beam energy range 5-50 A MeV. The enhancements of the total cross sections for ...reaction 6He+Si compared with reaction 4He+Si and 9Li+Si compared with reactions 6,7Li+Si have been observed. The performed microscopic analysis of total cross sections for reactions 6He+Si and 9Li+Si based on numerical solution of the time-dependent Schrödinger equation for external neutrons of projectile nuclei 6He and 9Li yielded good agreement with experimental data.
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