D. A. Tekueva

New experiment on search for the resonance absorption of solar axion emitted in the M1 transition of 83Kr nuclei

Axions with an energy of 9.4 keV emitted in the M1 transition of 83Kr nuclei in the Sun have been sought in the resonance absorption reaction A + 83Kr → 83Kr* → 83Kr + γ, e (9.4 keV). A proportional gas chamber filled with krypton and placed in a low-background setup at the underground laboratory of the Baksan neutrino observatory was used to detect γ-ray photons and electrons appearing after the decay of a nuclear level. As a result, a new constraint has been determined on the isoscalar and isovector coupling constants of the axion with nucleons: |gAN3– gAN0| ≤ 1.29 × 10–6. This constraint results in the following new bound on the mass of the axion in the hadronic axion model: mA ≤ 100 eV (95% C.L.).

First result of the experimental search for the 2K-capture of 124Xe with the copper proportional counter

First result of experiment for searching of 2K-capture of 124Xe with the large-volume copper proportional counter (LPC) is given. The 12 liters sample with 63.3% (44 g) of 124Xe was used in measurements. The limit on the half-life of 124Xe with regard to 2K(2ν)-capture for the ground state of 124Te (0+ → 0+, g.s.) has been found: T1/2 ≥ 4.67 × 1020 yr (90% C.L.). A sample with volume 52 liters comprising of 124Xe (10.6L - 58.6 g) and 126Xe (14.1L - 79.3 g) will used at the next step of the experiment to increase a sensitivity of 2K-caption of 124Xe registration. In this case sensitivity to the investigated process will be at the level of S = 1.46 × 1021 yr (90% C.L.) for 1 year measurement.

A technique for searching for the 2K capture in 124Xe with a copper proportional counter

An experimental technique for searching for the 2K capture in 124Xe with a large low-background copper proportional counter is described. Such an experiment is conducted at the Baksan Neutrino Observatory of the Institute for Nuclear Research of the Russian Academy of Sciences. The experimental setup is located in the Low-Background Deep-Level Laboratory at a depth of 4900 m.w.e., where the flux of muons of cosmic rays is suppressed by a factor of 107 relative to that at the Earth’s surface. The setup incorporates a proportional counter and low-background shielding (18 cm of copper, 15 cm of lead, and 8 cm of borated polyethylene). The results of processing the data obtained in 5 months of live measurement time are presented. A new limit on the half-life of 124Xe with respect to the 2K capture is set at the level of 2.5 × 1021 years.

Search for resonant absorption of solar axions emitted in M 1-transitions in 83 Kr nuclei: Second stage of the experiment

Axions with energies of 9.4 keV putatively produced in the Sun via an M1-transition in the 83Kr nucleus are searched for using the reaction of resonant absorption: A +83Kr →83Kr* →83Kr + γ, e (9.4 keV). The γ-quanta and electrons are detected with a proportional counter filled with krypton and placed in a low-background setup. A new upper limit on the axion–nucleon coupling constant is imposed: |g AN 3 g AN 0 |≤1.02 106. For the hadronic axion, this implies a new upper limit on the axion mass: m A ≤ 79eV at the 95% confidence level.

Search for 2K(2ν)-capture of 124Xe

The results of a search for two neutrino mode of double K-capture of 124Xe using a large copper low-background proportional counter are presented. Data collected during 3220 hours of measurements with 58.6 g of 124Xe provides us to a new limit on the half-life of 124Xe regarding 2K-capture at the level: T1/2 ≥ 2.0 × 1021 years at a 90% confidence level.

Search for two-neutrino 2K capture in 124Xe: the method and preliminary results

The technique used in the experiment in the search for the process of 2K2ν-capture in 124Xe using large high-pressure proportional counters is briefly described. The measurements with a xenon sample enriched to 21% (or ~57 g) of the 124Xe isotope carried out for 3340 hours yielded a zero signal. The resultant upper limit on the 124Xe half-life with respect to the 2ν-mode of the nuclear capture of two K-shell electrons amounts to T1/2>4.6 1021 yr at the 90% confidence level.

Results of Searching for Solar Hadronic Axions Emitted in the M1 Transition in 83Kr Nuclei

Axions with the energy of

New Constraints on the Axion–Photon Coupling Constant for Solar Axions

9.4