# LXX International conference "NUCLEUS – 2020. Nuclear physics and elementary particle physics. Nuclear physics technologies"

Oct 11 – 17, 2020
Online
Europe/Moscow timezone

## A Search for Resonant Absorption of Solar Axions via the Tm-containing Bolometer

Oct 14, 2020, 6:10 PM
1h
Online

#### Online

Poster report Section 5. Neutrino physics and astrophysics.

### Speaker

Evgeniy Unzhakov (Petersburg Nuclear Physics Institute)

### Description

The existence of an axion (a hypothetical pseudoscalar boson) was originally considered as a consequence of sponatneous breaking of newly introduced chiral symmetry, which was suggested in 1977 by R. Peccei and H. Quinn in attempt to solve the strong CP problem. The interactions of axion with ordinary matter are described via the effective coupling constants that are inversely proportional to the symmetry breaking scale $f_A$. The experimental searches for axion have been attempted ever since its original introduction, although none had yielded positive results so far.

After exclusion of "standard" axion (that assumed $f_A \approx 250$ GeV, comparable to the electro-weak scale), the theoretical model were modified so that $f_A$ value was allowed to become arbitrary large, therefore supressing the axion couplings and reducing its mass. This led to the appearance of light and weakly interacting "invisible" axion, which naturally became the viable dark matter candidate, further stimulating the motivation for its experimental discovery.

Axions should be intensely produced inside stellar cores and significant portion of axion experiments is targeted towards the detection of solar axions. Due to the axion-nucleon coupling axions can undergo resonant absorption in nuclear transitions of M1-type. A series of experiments were performed at Petersburg Nuclear Physics Institute searching for the resonant absorption of solar axions by several target nuclei ($^7$Li [1], $^{57}$Fe [2], $^{169}$Tm [3], $^{83}$Kr [4]).

A new technique, developed in collaboration with Max Planck Institute for Physics (Munich) and Kurchatov Institute (Moscow), allows for a significant increase in experiment sensitivity by employing the cryogenic bolometer detector based on the Tm-containing crystal [5]. This new approach scalable and can be potentially used for installation with a kg scale target.

1. A. V. Derbin et al., JETP Lett. 81 (2005) 365-370.
2. A. V. Derbin et al., Phys.Atom.Nucl. 74 (2011).
3. A. V. Derbin et al., Phys.Rev. D 83 (2011) 023505.
4. Yu. M. Gavrilyuk et al., JETP Lett. 107 (2018) no.10, 589-594.
5. E. Bertoldo et al, Nucl. Instrum. Meth. A 949 (2020) 162924.

### Primary author

Evgeniy Unzhakov (Petersburg Nuclear Physics Institute)