Separation efficiency of the MASHA facility for short-lived mercury isotopes

The mass-separator MASHA built to identify Super Heavy Elements by their mass-to-charge ratios is described. The results of the off- and on-line measurements of its separation efficiency are presented. In the former case four calibrated leaks of noble gases were used. In the latter the efficiency was measured via 284 MeV $^{40}$ Ar beam and with using the hot catcher. The ECR ion source was used in both cases. The $\alpha $ -radioactive isotopes of mercury produced in the complete fusion reaction $^{40}$ Ar+ $^{144}$ Sm $\rightarrow ^{184-xn}$ Hg+xn were detected at the mass-separator focal plane. The half-lives and the separation efficiency for the short-lived mercury isotopes were measured. Potentialities of the MEDIPIX detector system have been demonstrated for future use at the mass-separator MASHA.     

Quasi-isentropic compressibility of deuterium and helium at pressures of 1500–5000 GPa

The quasi-isentropic compressibilities of deuterium and helium plasmas are measured in the pressure range 1500–5000 GPa at densities up to 8 g/cm³ using spherical experimental devices and an X-ray complex consisting of three betatrons and a multichannel optoelectronic system for taking X-ray images. The experimental results demonstrate the possibilities of high-energy-density experimental physics to reproduce the extreme states of substance typical of the Universe under laboratory conditions using the energy of traditional condensed explosives.     

Experimental search for the radiative capture reaction d + d → 4He + γ from the ddμ muonic molecule state J = 1

A search for the muon-catalyzed fusion reaction d + d → ⁴He + γ in the ddμ muonic molecule was performed using the experimental installation TRITON with BGO detectors for γ-quanta. A high-pressure target filled with deuterium was exposed to the negative muon beam of the JINR Phasotron to detect γ-quanta with the energy 23.8 MeV. An experimental estimation for the yield of radiative deuteron capture from the ddμ state J = 1 was obtained at the level of η _γ ≤ 8 × 10^?7 per fusion.     

Experimental investigation of muon-catalyzed dt fusion in wide ranges of D/T mixture conditions

A vast program of the experimental investigation of muon-catalyzed dt fusion was performed on the Joint Institute for Nuclear Research phasotron. Parameters of the dt cycle were obtained in a wide range of the D/T mixture conditions: temperatures of 20–800 K, densities of 0.2–1.2 of the liquid hydrogen density (LHD), and tritium concentrations of 15–86%. In this paper, the results obtained are summarized.     

Experimental study of nuclear fusion reactions in a ptμ system

By means of muon catalysis we study the phenomena in a pt-fusion, which have been previously investigated in the only experiment and now are at the frontier of nuclear few-body physics. The experiment is aimed at measuring the yields of the reaction products: ??-quanta, conversion muons and e ⁺ e ^? pairs. As a result we plan to measure the pt-fusion partial product yields (first time for e ⁺ e ^? pairs) with accuracy not worse than 10%, and this will enable us to obtain the nuclear reaction rates in M1 and E0 transitions in A = 4 system.     

Deuterium High-Pressure Target

The design of deuterium high-pressure target of 76 cm³ volume developed to study muon catalyzed fusion in diffusion-pure deuterium over an 80–800 K temperature range at up to 150 MPa pressure is presented. This revised version was published online in August 2006 with corrections to the Cover Date.     

40-MCi tritium source of antineutrinos

Some technical and technological aspects of development, design, and safe operation of an artificial tritium source with an antineutrino activity of 40 MCi for experiments to measure the neutrino magnetic momentum are considered.     

Hydrogen and helium in nickel and 12Kh18N10T steel

A brief review of data for the influence of helium on the hydrogen sorption and mechanical properties of nickel and 12Kh18N10T steel is presented. When in the metallic matrix, helium considerably deteriorates the ductility of these metals. It is shown that ³He present in 12Kh18N10T steel generates high-energy hydrogen traps.     

Properties of very n -rich He isotopes

Low-energy spectra of the ^{8, 10}He nuclei were investigated in the (t, p) -type reactions at small centre-of-mass angles using ～ 25 AMeV beams of ⁶He and ⁸He nuclei. The 0⁺ ground state (g.s.) of ⁸He and excited states, 2⁺ at 3.6-3.9MeV and (1⁺) at 5.3-5.5MeV, were populated with cross-sections of 200, 100-250, and 90-125μb/sr, respectively. To account for a near-threshold anomaly observed in the ⁸He spectrum the population of a 1^- continuum (soft dipole excitation) was considered. The lowest-energy group of events in the ¹⁰He spectrum was observed at ～ 3 MeV with a cross-section of ～ 140 μb/sr. This result is consistent with the previously reported observation of ¹⁰He providing a new g.s. position for ¹⁰He at about 3MeV.     

Experimental investigation of muon-catalyzed t + t fusion

The muon-catalyzed fusion (μCF) process in tritium was studied by the μCF collaboration on the muon beam of the JINR Phasotron. The measurements were carried out with a liquid tritium target at the temperature 22 K and density approximately 1.25 of the liquid hydrogen density (LHD). Parameters of the μCF cycle were determined: the ttμ muonic molecule formation rate λ _ttμ = 2.84(0.32) μs⁻¹, the ttμ fusion reaction rate λ _f = 15.6(2.0) μs⁻¹, and the probability of muon sticking to helium ω _tt = 13.9(1.5)%. The results agree with those obtained earlier by other groups, but better accuracy was achieved due to our unique experimental method. The article is published in the original.