Systematic study of forward-angle inclusive yields of nuclei with atomic numbers 8 < Z < 20 produced in nucleus-nucleus collisions of the 40Ar projectile on the 9Be target in the Fermi energy domain (36.5 A MeV) was carried out. The reaction products were measured by using the double achromatic fragment-separator COMBAS in the spectrometry mode at Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research (Dubna). Relative yields of isotopes were obtained and compared with the empirical parametrization of fragmentation cross section (EPAX), abrasion–ablation (AA) and available experimental data.

Precision high-voltage sources have been developed for nuclear radiation detectors (semiconductor detectors, detectors based on photoelectronic multipliers, etc.). Instead of a specialized high-voltage transformer, a common network ( 220 V) POL-12012 transformer was used together with a voltage multiplier. The electrical parameters of the units are as follows: range, from 0 to ±2500 V; power, ≤10 W; efficiency, up to 77

In heavy-ion-induced projectile fragmentation reactions at Fermi energies vast amount of different nuclides far from stability line are born. These neutron or proton-reach isotopes can be used as secondary beams to obtain even more exotic new isotopes or to study nuclear interactions of halo nuclei and their radii and other yet unsolved scientific problems. Radioactive isotopes produced in fragmentation reactions can be used in medical and industrial applications. In this paper we present velocity and isotope distributions of fragments from Na to Ca obtained in the collision of ^40 Ar beam of 36.5 A MeV on ^9 Be target on COMBAS mass-spectrometer at FLNR, JINR. We compare the experimental results with the calculations fulfilled in combined transport-statistical model and show good agreement between them.

The projectile fragmentation reactions of 22Ne at 42 MeV/nucleon on 9Be and 181Ta targets have been studied by the double achromatic kinematic separator COMBAS at the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research (Dubna). Velocity distributions of the fragments were measured and the competition between different mechanisms was observed. The production cross sections have been obtained and compared with the empirical parametrization of fragmentation cross section (EPAX) and heavy-ion phase space exploration (HIPSE) models.

Analyses are presented of isotope and velocity distributions of light fragments obtained in the projectile fragmentation reactions of 18 O at 35 A MeV on 9 Be and 181 Ta targets measured at magnetic COMBAS mass-separator at the U400M Research Facility in JINR. The velocity distributions are parameterized by a direct breakup contribution at beam velocity plus an additional dissipative contribution at lower velocities. The results of these fits are compared with predictions by transport calculations and empirical fragmentation models.

Neutron-removal cross-section ( σ-xn ) measurements of neutron-rich light nuclei were performed on the COMBAS fragment-separator with a multi-detector Si telescope at intermediate energies (22-34) MeV/nucleon. The removals of one neutron from8Li and9Be, two neutrons from6 He and10 Be and four neutrons from 8 He were observed from the reactions on a Si-CsI(Tl) telescope. Results of σ-xn for6 He,8 He,8 Li,9 Be and10 Be nuclei were obtained and compared with those of previously measured data. The data indicate that4 He is a good core within6 He and8 He. Furthermore, we found that9,10 Be nuclei disintegrated by one- and two- neutron removal reaction, respectively.

The velocity, charge, and isotopic distributions of the products of nuclear reactions with 2 ≤ Z ≤ 11 have been studied in combinations of 18 O (35 MeV/nucleon) + 181 Та ( 9 Ве) with a different isotope spin. The correlation of the isotope yields for the detected light elements with value Qgg has been established. The cross sections for the formation of neutron-rich nuclei have been measured and their yields in reactions with different neutron skin have been compared. A qualitative interpretation of the phenomenon of a significant increase in the probability of the formation of neutron-rich nuclei of light elements in reaction 18 О (35 MeV/nucleon) + 181 Та in comparison with 18 О (35 MeV/nucleon) + 9 Ве obtained in the reactions with the removal of a proton from the projectile nucleus has also been presented.

Secondary beams (6Li,7Be,8B) were obtained by the separation of fragmentation products of a15N ion beam (50 MeV/A) impinging on a Be target using the COMBAS spectrometer. The secondary products were detected by a telescope consisting of five Si-detectors (dE) and a stop CsI(Tl) detector. The telescope allowed us to achieve unambiguous particle identification of fragments originating from incident secondary beams as well as their reaction products resulting from interaction with the Sidetectors, chosen as a secondary target. This way, break-up reactions of6Li,7Be and8B have been studied in this experiment, in particular the longitudinal momentum distributions of7Be fragments in the break-up of8B on a Si have been measured at 30 MeV/A.

Up to date analysis of velocity and isotope distributions of light fragments obtained in the projectile fragmentation reactions of 18 O at 35 A MeV on 9 Be and 181 Ta targets measured at COMBAS fragment separator at the U400 M Research Facility in JINR are presented. The results of velocity spectra analytical parameterization and isotopic ratios are compared with the ones obtained in the experiments presented in the literature. The discussion of the different mechanisms involved in these types of the reactions is given.

Secondary beams (6Li,7Be,8B) obtained by separation of fragmentation products of 15N beam (50 A MeV) impinging on a Be target using COMBAS spectrometer. The secondary products will be detected by a telescope consisting of five Si-detectors (dE) and CsI(Tl) detector (Er). By the dE-E method, the telescope allowed us to achieve unambiguous particle identification originating from incident secondary beams as well as theirs reaction products resulting from reactions with one of Si detectors chosen as the target. Accordingly, break-up reactions of 6Li, 7Be and 8B were studied in this experiment.

Preliminary results of measurements of the total reaction cross sections σR for nuclei4He,6He,8He,7Li,8Li,9Li,11Li,7Be,9Be,10Be,11Be,12Be,8B,10B,11B and12B nuclei at energy range (10-50) AMeV with28Si target is presented. The secondary beams of light nuclei were produced by bombardment of the 15N (50 AMeV) primary beam on Be target and separated by COMBAS fragment- separator. In dispersive focal plane a horizontal slit defined the momentum acceptance as 1% and a wedge degrader of 600 µm Al was installed. The Bρ of the second section of the fragment-separator was adjusted for measurements in energy range (10-45) AMeV. The strong absorption model reproduces the A-dependence of σR , but not the detailed structure. We are comparing our experimental data with predictions of microscopic (dashed line) and strong absorption model, Glauber multiple scattering theory and preliminary results are obtained.

Neutron-removal cross-section ( σ -xn ) measurements of neutron-rich light nuclei were performed on the COMBAS fragment-separator with a multi-detector Si telescope at intermediate energies (22-34) MeV/nucleon. The removals of one neutron from 8 Li and 9 Be, two neutrons from 6 He and 10 Be and four neutrons from 8 He were observed from the reactions on a Si-CsI(Tl) telescope. Results of σ -xn for 6 He, 8 He, 8 Li, 9 Be and 10 Be nuclei were obtained and compared with those of previously measured data. The data indicate that 4 He is a good core within 6 He and 8 He. Furthermore, we found that 9,10 Be nuclei disintegrated by one- and two- neutron removal reaction, respectively.

The basic ion-optical characteristics of the luminosity and the high-resolution of kinematic separator COMBAS realized for the first time on the strong focusing principle are presented. The developed facility allows to separate the high-intensity secondary radioactive beams in a wide range of mass numbers A and atomic numbers Z which are produced in heavy ion reactions in the energy range of 20 ≤ E ≤ 100 MeV/A (Fermi energy domain). Two distinct detector systems such as realized Si strip detector telescope and the promising development of the three dimension time-projection chamber are discussed. Program of the investigations of nuclear reaction mechanisms at intermediate energies of 20–100 MeV/A, measurement of the radii of unstable nuclei, study of the cluster structure of light nuclei near the nuclear drip-line and search of 26,28O resonances in exchange reactions is proposed. The upgrading of experimental facility by the integration of COMBAS separator with the Ion Catcher is discussed.

Preliminary results of measurements of the total reaction cross sections σR for weakly-bound 6,8He and 8,9Li nuclei at energy range (25–45)/A MeV on 27Al and 208Pb targets are presented. The secondary beams of 6,8He and 8,9Li were produced by bombardment of the 11B (33 A MeV) primary beam on Be (89 mg cm–2) target and separated by COMBAS fragment-separator. In dispersive focal plane a horizontal slit defined the momentum acceptance as 1% and a wedge degrader of 200 μm Al was installed. The B ρ of the second section of the fragment-separator was adjusted for measurements in energy range (25–45)/A MeV. The secondary products were detected by a telescope consisting of two Si ΔE detectors 300, 1000 μm and E-detector, which consisted of nine CsI/Tl granules.

The (Δ E 1 , Δ E 2 , E ) multidetector telescope has been developed and tested. The telescope is a compact combination of two 32-strip silicon Δ E 1 -, Δ E 2 -detectors and a scintillation E -detector, which is a 3 × 3 array of CsI(Tl) crystals. A timing signal can be obtained from any of the Si detectors for time-of-flight (TOF) measurements. Single-channel and 32-channel charge-sensitive preamplifiers have been developed and manufactured for the multidetector module to serve the Δ E - and E -detectors with high efficiency and sensitivity. Reaction products obtained in the 40 Ar (35 MeV/nucleon) + 9 Be reaction have been unambiguously identified in the experiment by mass number A and atomic number Z .

Обсуждается создание экспериментального комплекса на базе светосильного фрагмент-сепаратора КОМБАС и быстродействующего ионного кетчера. Представлены основные характеристики фрагмент-сепаратора КОМБАС и ионного кетчера, определяющие перспективность предлагаемой комбинации. Ожидается, что реализуемый комплекс позволит получать вторичные пучки радиоактивных ядер более высокого качества по сравнению с пучками, получаемыми методом “in-flight” сепарации. Планируется использование комплекса в тандеме с пост-ускорителем для получения моноизотопных и монохроматических интенсивных вторичных пучков радиоактивных ядер в широком диапазоне массовых чисел А и атомных номеров Z. Предлагается перечень перспективных научных задач, для реализации которых требуются высокие интенсивности и качество получаемых вторичных пучков экзотических ядер.