Search

A description of a procedure for selecting events during the absorption of stopped pions in thin targets is presented. This approach is based on the use of two monitor Si-detectors and a “live” target, which is also an Si-detector, as the last layers of the moderator. Setting the thresholds on monitor detectors and analyzing signals from a “live” target allow one to select pions with a residual range corresponding to the target thickness and reliably exclude the background from stops in the monitor system. It is shown that this method provides an efficiency of identifying stopped π–-mesons of 90%.

The structure of levels of the 8He heavy helium isotope has been studied in the 9Be $$({{\pi }^{ - }},p)X$$ and 10B $$({{\pi }^{ - }},pp)X$$ stopped pion absorption reactions. Measurements have been performed with a two-arm multilayer semiconductor spectrometer at the LANL. Indications to the existence of a soft dipole mode at the excitation energy $${{E}_{x}} \approx 3$$ MeV have been obtained. A state with a high excitation energy of 12.2(5) MeV has been observed for the first time.

An experimental search is conducted for the formation of the heavy 9He isotope of helium upon the absorption of stopped pions by 14C nuclei. The structure of 9He levels in the missing mass spectra in reactions 14C(π–, p4He)Х and 14C(π–, d3He)Х is studied. A state with a high energy of excitation of 12.5 MeV and a state width of 1.5 MeV is detected for the first time. Suppression of the formation of ground state 9He in the considered reactions is established.

A survey of experimental results on the level structure in the heavy helium isotope $${}^{6}$$ He that were obtained in reactions induced by stopped pion absorption in $${}^{9}$$ Be, $${}^{10,11}$$ B, and $${}^{12}$$ C light nuclei is presented. The respective measurements were performed on the low-energy pion channel of the accelerator at the Los Alamos National Laboratory (LANL) by means of a two-arm semiconductor spectrometer. A high statistical significance of the results was attained over a broad excitation-energy range extending up to 40 MeV. Several highly excited states, including $$t+t$$ cluster resonances, were revealed for the first time.

The differential cross sections for the 12C(3He, t)12N reaction leading to formation of the 1+ (ground state), 2+ (0.96 MeV), 2− (1.19 MeV), and 1− (1.80 MeV) states of 12N are measured at E(3He) = 40 MeV. The analysis of the data is carried out within the modified diffraction model and distorted wave Born approximation. Increased rms radii have been obtained for the ground, 2− (1.19 MeV), and 1− (1.80 MeV) states. We revealed that 12B, 12N, and 12C in the isobaric analogue states with T = 1, and spin-parities 2− and 1− have increased radii and exhibit properties of neutron and proton halo states.

The properties of detectors based on epitaxial layers of silicon carbide (SiC) are presented. It is shown that the developed detectors have good spectrometric characteristics when detecting a particles with energies of up to 8 MeV. The pulse height defect was measured in SiC detectors under irradiation by accelerated xenon ions with different energies. It is shown that this parameter in the spectroscopic analysis of Xe ions is ∼45% of the true energy of the particles in question.

The spectra of 3,4He charged particles produced in stopped pion absorption by nuclei were measured for 17 nuclei in the mass-number range of 6 ≤ A ≤ 209 by means of a semiconductor spectrometer. These data were analyzed on the basis of a phenomenological model where the absorption reaction in question is treated as a three-stage process: primary absorption by intranuclear clusters, preequilibrium stage, and evaporation stage. It is shown that a dominant contribution to the production of helium isotopes with energies not less than 20 MeV comes from the preequilibrium stage. The contribution of the knockout and pickup mechanisms to 3,4He production is estimated.

A study of the neutron structure of the ground state of 7He has been performed by means of registration and analysis of the decay channels of the residual nuclei following absorption of stopped pions. In particular, the reactions 9Be(π−, d) X and 11B(π−, dd) X have been investigated where X denotes any system with five neutrons and two protons — the constituencies of a 7He nucleus. The results point out to the existence of a halo-like configuration of the ground state of 7He with all three neutrons outside of the alpha particle core. The structure of this complicated halo-like state is determined by the correlations of neutrons in the p3/2 and p1/2 shells. The result would be in agreement with the previous works pointing out to a considerable mixing of configurations containing neutrons in the p3/2 and p1/2 states.

The structure of the levels of heavy helium isotope 8He is investigated using the reactions of stopped-pion absorption by carbon isotopes 12С(π−, p3He)X, 14С(π−, d4He)X, and 14С(π−, t3He)X. Measurements are made with the two-arm multilayer semiconductor spectrometer at the LANL accelerator. Excited states of the 8He nucleus with energies of excitation of up to ~ 20 MeV are sought using the measured missing-mass spectra for these reactions. An excited state with Ex ≈ 6.4 MeV and Г ≤ 1 MeV is observed for the first time. Its structure is probably due to two valence nucleons on the (1p1/2)2 shell.

In this paper we have focused on characteristics of detectors based on 4H-SiC semiconductor. The typical thickness of the active layer was between 25 ×m and 100 ×m. Circular Schottky contacts with diameters of 2.0 mm and 3.0 mm were prepared by evaporation of Au/Ni double layer. The reverse and forward current-voltage and also capacitance-voltage characteristics were measured at room temperature up to 600 V. The doping concentration profile was calculated. The obtained concentration of doping was below $1 \times 10^{14} cm^{-3}$. The detection properties of 4H-SiC particle detector were tested using two radioisotopes: 241Am and 238Pu.

Helium 5Hе states are sought in missing-mass (MM) spectra from reactions of the absorption of stopped pions: 10В(π−, dt)Х and 11В(π−, tt)Х. The experiment is conducted using the LANL accelerator equipped with a two-arm semiconductor charged-particle spectrometer. The parameters of the ground state agree with the literature data. The best fit for the first excited level is obtained at Er = 1.8(5) MeV and Γ = 4.7(7) MeV. Neither of the two reactions produce statistically significant evidence for the presence of highly excited (Ex ≥ 20 MeV) states of 5Hе.

The current state of studies in the field of development of multilayer semiconductor systems (semiconductor detector (SCD) telescopes), which allow the energy to be precisely measured within a large dynamic range (from a few to a few hundred MeV) and the particles to be identified in a wide mass range (from pions to multiply charged nuclear fragments), is presented. The techniques for manufacturing the SCD telescopes from silicon and high-purity germanium are described. The issues of measuring characteristics of the constructed detectors and their impact on the energy resolution of the SCD telescopes and on the quality of the experimental data are considered. Much attention is given to the use of the constructed semiconductor devices in experimental studies at accelerators of PNPI (Gatchina), LANL (Los Alamos) and CELSIUS (Uppsala).

An experiment was done to search for states with a neutron halo in 12B. The measurements were carried out at the cyclotron of the University of Jyvaskyla (Finland) using Large Scattering Chamber (LSC). The idea of the work was to search for two states with the expected neutron halo, 1 ̄ and 2 ̄. Differential cross sections with excitation of 12B states, including abovementioned states, were observed. The preliminary calculations on halo radii by the method of asymptotic normalization coefficients for the 2 ̄ and 1 ̄ states which are in a discrete spectrum gave following values: 5.6 fm and 7.4 fm, which is much larger than the radius of the valence neutron in the ground state. But strictly the presence of a neutron halo can be confirmed only for 1 ̄ state. The 2 ̄ state can be considered only as candidate for halo. An unexpected result was obtained for the 3 ̄, 3.39 MeV state, which is in continuum 19 keV above the decay threshold 12B → 11B + n, preliminary estimation for its halo radius is ∼ 6.5 fm. This indicates that the halo can be present in this state as well. But strict conditions for neutron halo are not fulfilled in the same way as for 2 ̄ state. Until now, the neutron halo in unbound states has been observed only for the members of the rotational bands.

The parameters of detectors based on CdZnTe crystals with a sensitive volume of approximately 1500 mm3 are investigated. It is shown that at room temperature the characteristics of these detectors are high enough for spectrometry of γ rays from 241Am, 57Co, 137Cs, and 60Co sources.

The characteristics of two modifications of the semiconductor (s.c.d.) setup consisting of telescopes on the basis of silicon detectors are presented. These settings allow performing a precision measurement of energy in a large dynamic range (from a few to hundreds of MeV) and particle identification in a wide range of masses. The issues of measurement of the characteristics of s.c.d. telescopes and their impact on the quality of the obtained experimental data are considered. Considerable attention is paid to the use of created semiconductor devices for the search for and spectroscopy of light exotic nuclei on the accelerators of PNPI (Gatchina) and LANL (Los Alamos).

The differential cross sections of the $^{12}$C($^3$He,t)$^{12}$N reaction leading to formation of the 1$^+$ (ground state), 2$^+$(0.96 MeV), 2$^{-}$(1.19 MeV), and 1$^{-}$(1.80 MeV) states of $^{12}$N are measured at $E$($^3$He)=40 MeV. The analysis of the data is carried out within the modified diffraction model (MDM) and distorted wave Born approximation (DWBA). Enhanced $rms$ radii were obtained for the ground, 2$^{-}$(1.19 MeV), and 1$^{-}$(1.80 MeV) states. We revealed that $^{12}$B, $^{12}$N, and $^{12}$C in the IAS with T=1, and spin-parities 2$^{-}$ and 1$^{-}$ have increased radii and exhibit properties of neutron and proton halo states., Comment: 6 pages, 4 figures, 2 tables

The properties of silicon (Si) and silicon carbide (4Н-SiC) detectors after their exposure to different integral fluxes of xenon (Xe) ions are presented. The detectors were irradiated at the IC-100 cyclotron of the Flerov Laboratory of Nuclear Reactions at the Joint Institute for Nuclear Research. It is shown that the degradation of the spectroscopy characteristics of a SiC detector occurs at higher doses compared to a similar Si detector.

A study of the neutron structure of the ground state of 7He has been performed by means of registration and analysis of the decay channels of the residual nuclei following absorption of stopped pions. In particular, the reactions 9Be(π−, d)X and 11B(π−, dd)X have been investigated where X denotes any system with five neutrons and two protons — the constituencies of a 7He nucleus. The results point out to the existence of a halo-like configuration of the ground state of 7He with all three neutrons outside of the alpha particle core. The structure of this complicated halo-like state is determined by the correlations of neutrons in the p3/2 and p1/2 shells. The result would be in agreement with the previous works pointing out to a considerable mixing of configurations containing neutrons in the p3/2 and p1/2 states. peerReviewed

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.

A study of the neutron structure of the ground state of 7He has been performed by means of registration and analysis of the decay channels of the residual nuclei following absorption of stopped pions. In particular, the reaction 9Be ( π − , d )X have been investigated where X denotes any system with five neutrons and two protons – the constituencies of a 7He nucleus. It was shown that the structure of 7He is determined by correlations of two neutrons in the states 6He (0+), 6He (2+) and one neutron in the shell p3/2. The 4He+3n structure is not manifested in the ground state of 7He. The obtained results are consistent with the known data on considerable mixture of configurations “6He in its ground and first excited states plus a neutron” in the ground state of 7He. Comparison of the diffraction components of the differential cross-sections of the charge-exchange reactions (t, 3He) measured on 6Li and 7Li allowed extracting the radius of particle-unstable nucleus 7He. The latter occurred to be approximately equal to those of 6He and 8He. The obtained result indicates to existence of the halo-like structure in 7He.

The results based on the spectroscopy of superheavy hydrogen isotopes (4−7H), heavy helium isotopes (6,7He), and heavy lithium isotopes (7−12Li) produced in stopped pion absorption by light nuclei were analyzed. Search for nuclear states was performed in inclusive and correlation measurements of missing mass spectra. A broad range of excitation energies studied in correlation measurements provided the possibility of search for isobaric analog states and cluster resonances. A comparison with experimental and theoretical results of other authors was conducted.

Analysis of the two-dimensional Dalitz plot measured in the reaction 14C(π–, pd)X allows us to follow the absorption of pions by cluster 3p and identify signs of the configuration 3p + 11Li in the 14C nucleus. The highly excited state of 12,13Be beryllium isotopes with excitation energies E* ≈ 30 MeV and which decay with the emission of hydrogen isotopes is observed for the first time: 12Be* → p + 11Li and 13Be* → d + 11Li.

The results from analyzing the yields of protons (p), deuterons (d), and tritons (t) formed in the absorption of stopped π– mesons by intranuclear clusters are presented. The contributions from cluster absorption to the production of hydrogen isotopes in stopped pion absorption reactions are determined. Phenomenological formulas are proposed for describing the mass number (A) dependences of the yields of the primary protons with ∼15% precision in the mass number range of 6 < A < 209 (and of the primary deuterons and tritons in the mass number range of 59 < A < 209). Evidence is observed of the constancy of the ratio between the elemental absorption widths for the absorption of pions by pp and pn pairs over the investigated range of mass numbers.

The level structure of lithium isotope 6Li is studied in the reaction of the absorption of stopped pions 12С(π−, tt)X. States are sought up to excitation energies of ~40 MeV in the missing mass spectrum. Data on highly excited states are analyzed to determine their origins. The final results are compared to those from searches for the highly excited states of heavier lithium isotopes produced in the reaction of the absorption of stopped pions.

Formation of the 7He heavy isotope was studied in the reactions of stopped pion absorption by light nuclei 9Be, 10,11B and 12,14C. Measurements were performed using the two-arm multilayer semiconductor spectrometer. Contrary to the results of other studies, we observed several narrow highly excited states (Ex > 16 MeV) of 7He. From the analysis of the continuous excitation spectrum in reactions 9Be(π−, d)X and 11B(π−, dd)X it was obtained first indication that the 4He+3n structure is not present in the ground state of 7He.

The differential cross sections for elastic and inelastic 11B + α scattering were measured at the alpha-particle energy of 65 MeV, the inelastic-scattering processes leading to the excitation of known states of 11B up to excitation energies of about 14 MeV. Data on elastic scattering were analyzed together with those that were published earlier for lower energies. The cross sections for inelastic scattering were analyzed on the basis of the distorted-wave method. A modified diffractionmodel was used to determine the root-mean-square radii of excited states. The radii of states whose excitation energies were below about 7MeV were found to agree with radius of the ground state to within 0.1 to 0.15 fm. This result complieswith the traditional idea that the low-lying states of 11B have a shell structure. The possibility that these states belong to the predicted rotational bands, which, if any, are truncated to three states, cannot be ruled out either. The majority of the observed highly excited states are distributed among four rotational bands. The moments of inertia of these bands are close; for the band based on the 3/2− state at E* = 8.56 MeV, they are even higher than those of the Hoyle state in the 12C nucleus. The measured radii of states associated with these bands of 11B are larger than the ground-state radius by 0.7 to 1.0 fm and are also close to the radius of the Hoyle state. The results of the present study agree with the existing predictions that the cluster structure of the 11B nucleus is diverse at high excitation energies. The hypothesis that the 11B nucleus features a “giant” state of size commensurate with those in heavy nuclei was not confirmed.

Highly excited states of 6He are sought in the reactions involved in the absorption of stopped pions by 10,11B nuclei. Several levels in 6He are observed for the first time. A state with Ex ≈ 9.3(2) MeV and Γ ≈ 1.0(4) MeV is seen to form in two reactions: 10B(π−, pt)X and 11B(π−, dt)X. Two states are seen to form in the 10B(π−, pt)X reaction channel at energies above the threshold of 6He decay into two tritons (Ex ≥ 12.3 MeV): one state with Ex = 22(1) MeV, Γ = 2.7(1.4) MeV and the other with Ex = 27.0(8) MeV, Γ = 2.5(1.1) MeV.

Results are presented from analyzing the yields of protons (p), deuterons (d), and tritons (t) in pre-equilibrium stopped pion absorption reactions. Phenomenological formulas are proposed for describing the mass-number (A) dependences of these yields accurate to within 10–20% in the mass-number range of 6 < A < 209 (59 < A < 209 for t). The final results do not contradict the hypothesis that the predominant role in the formation of deuterons and tritons is played by pick-up on the surface of nuclei.

Results on the research of spectra and yields of p, d, t formed in the reaction of stopped pion absorption by atomic nuclei are presented. Unique data on charged particle formation on 17 isotopes have been obtained in wide mass range (6 < A < 209). Empirical model is proposed that allows to describe A-dependence of primary proton yields (with 10-15% precision) and to estimate the ratio of the elementary widths of pion absorption on pn and pp pairs R’ = 3.3±0.5.

The formation of the 7He heavy isotope has been studied in the 11B(π−, pt)7He, 11B(π−, dd)7He, and 10B(π−, pd)7He reactions of absorption of stopped π− mesons. No indications of the existence of a low-lying level with E x ∼ 1 MeV have been obtained in any of the three reactions. The existence of three narrow states with excitation energies E x = 3.1(1), 4.90(15), and 6.65(15) MeV has been proven. Highly excited states with E x = 16.9(5) MeV, Γ = 1.0(3) MeV, E x = 19.8(3) MeV, Γ = 1.5(3) MeV, and E x = 24.8(4) MeV, Γ = 4.6(7) MeV have been identified.

The experimental search for the production of heavy lithium isotopes 10-12 Li was carried out in the stopped π - -mesons absorption reactions on the radioactive target 14 C. Study of 10 Li has been performed in the missing mass spectra in 14 С(π - , pt)X and 14 С(π - , dd)X reactions. Three excited states of 10 Li were identified, thus, the broad state with a resonance energy E r = 6.1 ± 0.1 MeV has the highest excitation energy, compared with the previously observed levels. The resonance parameters of three low-lying excited states of 11 Li were determined in the 14 С(π - , pd)X reaction. In the 14 С(π - , pp)X reaction evidence for a 12 Li excited state E r = 4.0 ± 0.2 MeV and Γ = 1.1 ± 0.2 MeV has been found.

The excited states of light neutron-rich isotopes were studied in the reactions of stopped pion absorption. The level structure of the superheavy hydrogen isotopes 4–7H, heavy helium isotopes 6,7He and lithium isotopes 6-12Li were determined up to the excitation energy ∼ 30 MeV. For most nuclei results were obtained in several reaction channels. The wide range of excitation energies provided the possibilities to study isobar-analog states and cluster resonances. Our data are compared with theoretical and experimental results obtained up to now.

Experimental results are presented for the spectra and yields of t and 3He produced by nuclei in the reaction of stopped pion absorption. Contributions from different processes in the formation of particles are determined using a phenomenological model. The ratio of t and 3He yields agrees with the hypothesis of particle formation during the pre-equilibrium stage in the process of deuteron pick-up by primary nucleons on the surface of a nucleus.

Three narrow (Γ ≤ 0.5 MeV) low-lying states of 7He with excitation energies of 3.2(1) MeV, 4.9(2) MeV and 6.65(15) MeV are observed simultaneously for the first time in reactions of the absorption of stopped π−-mesons 11B(π−,pt)7He and 11B(π−,dd)7He. No indications of the existence of a level in the area of Ex ∼ 1 MeV are found. Highly excited 7He states with parameters Ex = 19.6(3) MeV, Γ = 1.7(4) MeV and Ex = 25.2(6) MeV, Γ= 4.8(9) MeV are observed.

The results of investigation of detector made of cadmium zinc telluride (CdZnTe or CZT) crystal with a working volume of 1500 mm3 are presented. The detector is shown to have good spectrometric characteristics in registering gamma radiation from 241Am, 57Co, 137Cs and 60Co sources and can be effectively used for low-background measurements.

Highly excited states of the 8Li isotope are sought in absorption reactions of π− mesons stopped by 10,11B isotopes. The ground and three excited states of the 8Li isotope are observed in inclusive measurements of reactions 10B(π−, d)X and 11B(π−, t)X. The states with excitation energies Ex ≈ 8.7 and 10.1 MeV are observed for the first time in correlation measurements of reactions 10B(π−, dt)X and 11B(π−, tt)X.

Experimental results on the spectra and yields of deuterons forming in the absorption reaction of stopped π− mesons by nuclei are presented. The A-dependences of deuteron yields are found. Contributions from various processes to the formation of deuterons are evaluated in the context of a proposed phenomenological model.

The possibility of designing a prototype of the scintillation transition radiation detector (Sci-TRD) based on a thin (∼200 μm) inorganic scintillator has been investigated. Vacuum and silicon photomultipliers have been used in the measurements with inorganic scintillator samples based on LuBO3:Ce and wavelength shifting fibers. The light collection coefficient has been measured for scintillator prototypes under exposure to X rays, and the quantity of photoelectrons has been experimentally determined by irradiating the Sci-TRD working substance with a 241Am X ray source. The electron-hadron rejection ratio of the proposed Sci-TRD is expected to be ∼30.

Differential cross-sections of the elastic and inelastic 13C + α scattering were measured at E(α) = 90 MeV. The root mean-square radii (< Rrms >) of 13C nucleus in the states: 8.86 (1/2−), 3.09 (1/2+) and 9.90 (3/2−) MeV were determined by the Modified diffraction model (MDM). The radii of the first two levels are enhanced compared to that of the ground state of 13C, confirming the suggestion that the 8.86 MeV state is an analogue of the Hoyle state in 12C and the 3.09 MeV state has a neutron halo. Some indications to the abnormally small size of the 9.90 MeV state were obtained. peerReviewed

The origin of the 9Li isotope is sought in missing-mass spectra measured in 11B(π−, d)X, 12C(π−, pd)X, and 14C(π−, dt)X stopped-pion absorption reactions. The parameters of the three observed low-lying excited states coincide with the literature data. A state with excitation energy Ex = 9.1 ± 0.1 MeV, lying above the threshold of 9Li decay into 6He + t, is observed for the first time.

Experimental results on the yields and spectra of protons produced during the absorption of stopped pions by nuclei are presented. The measurements were performed on the accelerator at the St. Petersburg Nuclear Physics Institute, Russian Academy of Sciences, using a two-arm semiconductor spectrometer of charged particles on a set of nuclei that includes light nuclei 6,7Li, 9Be, 10,11B, and 12C; medium nuclei 28Si, 40Ca, 59Co, and 93Nb; tin isotopes 114,117,120,124Sn; and heavy nuclei 169Tm, 181Ta, and 209Bi. The A dependences of the proton yields and their components are obtained. Some indications of the dominant role of pion absorption on intranuclear pp pairs in the formation of fast protons are presented.

A search for the 10Li formation was performed in missing mass spectra measured in stopped pion absorption reactions 14C(π−, pt)X and 14C(π−, dd)X. Three excited states of 10Li were found. The broad state with a resonance energy of ER = 6.13 ± 0.11 MeV has the highest excitation energy in comparison with levels observed earlier.

The structure of excited levels in the 7Li isotope is studied via inclusive and correlation measurements in the stopped π− meson absorption reactions 10B(π−, t)X and 12C(π−, dt)X, respectively. The experiment is conducted using a low-energy pion beam at the LAMPF meson factory. Analysis of the missing mass spectra reveals 7Li states with the resonance parameters (E x , Γ) (4.7, 0.1), (6.6, 0.9), (7.3, 0.1), (9.1, 2.8), and (9.6, 0.4) MeV. A highly excited state with E x ≈ 11.2 MeV (i.e., an isobar analog of 7He) is observed in the 10B(π−,t)X reaction. An excited state with E x = 10.3 ± 0.1 MeV and γ = 1.8 ± 0.4 Mev is observed for the first time in the 12C(π−,dt)X reaction.

Correlation measurements of the reaction of stopped pion absorption 11B(π−, tt)X are made with a semiconductor double-arm charged particle spectrometer on a low-energy pion beam at the LAMPF meson factory. Analysis of a two-dimensional Dalitz plot and the momentum distribution of the residual nucleus allows us to identify the absorption of pions in a 6Li intranuclear cluster and demonstrate the configuration 6Li + 5Heg.s is present in the 11B nucleus.

The results of an investigation of silicon (Si) and silicon carbide (SiC) detectors when irradiated with a beam of Xenon (Xe) ions are presented. The irradiation was carried out at the IC-100 cyclotron, JINR, Dubna. The effect of the Pulse Height Defect (PHD) in registering Xe ions with energies 165, 82 and 45 MeV is shown to be twice as large for SiC detectors as that for Si detectors. It is also shown that degradation of SiC detectors irradiated with heavy Xe ions occurs at doses an order of magnitude greater than for Si detectors. The measurement method described, including continuous detector calibration by alpha-particles, makes it possible to simultaneously control the characteristics of detectors during irradiation and determine the energy of a beam of ions.

A method for producing 10Be isotope from spent rods of the emergency protection and compensation systems of a fast neutron reactor is described. This isotope has found application in targets and radioactive beams for experiments at modern heavy-ion accelerators. The mass of 10Be obtained using this technique is 2.7 mg, which is five times the mass of this isotope produced throughout the world to date. A method for determining the 10Be concentration in the source material and intermediate fractions of its processing has been developed. This method is based on analysis of γ and β spectra of samples, measured by HPGe and Si(Li) detectors. A prototype of the 10Be oxide target has been manufactured. The parameters of the target prototype have been determined, and its vacuum testing has been performed.

In the present work we have analyzed evaporation spectra and yields of p,d,t formed in the reaction of stopped pion absorption. It is shown that the values of equilibrium temperature obtained through the usage of proposed model are in agreement with the values obtained in various other experiments. We also discuss the A-dependences of the evaporation yields and consider possible contributions of the “indirect” evaporation processes.

The excited states of heavy helium isotope 6He were studied in stopped pion absorption in the reactions 9Be(