V. N. Kornoukhov

Measurement of the cross sections for the production of the isotopes 74As, 68Ge, 65Zn, and 60Co from natural and enriched germanium irradiated with 100-MeV protons

The cross sections for the production of the radioactive isotopes 74As, 68Ge, 65Zn, and 60Co in metallic germanium irradiated with 100-MeV protons were measured, the experiments being performed both with germanium of natural isotopic composition and germanium enriched in the isotope 76Ge. The targets were irradiated with a proton beam at the facility for the production of radionuclides at the accelerator of the Institute for Nuclear Research (INR, Moscow). The data obtained will further be used to calculate the background of radioactive isotopes formed by nuclear cascades of cosmic-ray muons in new-generation experiments devoted to searches for the neutrinoless double-beta decay of 76Ge at underground laboratories.

Extraction method for preparing indium-containing liquid organic scintillators for solar neutrino detection for LENS experiment, low-energy neutrino spectroscopy

Extraction of In with solutions of 2-methylvaleric acid (H2MVA) in trimethylbenzene (TMB) was studied. Depending on pH of the equilibrium aqueous phase, the extracted indium species are In(2MVA)3 · 3(H2MVA), In(2MVA)3, [In(2MVA)x(OH)3−x]n, etc., where 2MVA is the 2-methylvalerate anion and n is the degree of polymerization. By the extraction method, In-containing liquid organic scintillators (LOSs) with the following parameters were obtained: [In] = 50–96 g l−1, transparency 2–3 m, light output 68% relative to TMB. Long-term precision trials of the scintillators in the Gran Sasso underground laboratory (Italy) confirmed that the scintillator parameters were stable and met the requirements of the LENS experiment. A procedure was developed for preparing solid anhydrous indium hydroxycarboxylates, and their properties were studied. LOSs based on solutions of solid indium hydroxycarboxylates in TMB were prepared and subjected to long-term trials in which the transparency and light output were monitored. One of the major factors responsible for the instability of indium-containing LOSs is the presence of water in the organic phase.

Cross sections for 68Ge production in natural- and enriched-germanium targets irradiated with protons of energy 100 MeV and background in experiments devoted to searches for the 2β0ν decay of 76Ge

The rate of 68Ge production at sea level under the effect of the nuclear component of cosmic rays is calculated. The calculation is based on the experimental values of the cross sections for 68Ge production in natural- and enriched-germanium targets (enrichment in 76Ge) irradiated with high-energy protons. The background from the decays of 68Ge can be a serious problem in new-generation experiments devoted to searches for the 2β0ν decay of 76Ge.

Production chain of isotopically modified ge-diodes for the 2β0ν-search with GERDA

The procurement of germanium-oxide (GeO2) depleted in 76Ge is presented. The quality control, the reduction and zone refinement as well as crystal pulling is described as new detection systems must be explored in order to reach the needs of modern rare event searches. The experiment GERDA aims at the detection of neutrinoless double beta (2β0ν) decay. The depleted germanium project aims at the demonstration that working BEGe detectors can be produced based on a realistic material supply chain maximizing the Ge-metal to Ge-diode yield in an optimal usage of the expensive isotopically modified material.