Eur. Phys. J. C (2008) 54: 61-72
https://doi.org/10.1140/epjc/s10052-008-0530-9

Regular Article - Experimental Physics

Search for solar axions emitted in the M1-transition of ⁷Li^* with Borexino CTF

¹ Dipartimento di Fisica Università and INFN Milano, Via Celoria 16, 20133, Milano, Italy
² Department of Chemical Engineering, A-217, Engineering Quadrangle, Princeton, NJ, 08544-0708, USA
³ Department of Physics, Princeton University, Jadwin Hall, Washington Rd, Princeton, NJ, 08544-0708, USA
⁴ Astroparticule et Cosmologie APC, 10 rue Alice Domon et Leonie Duquet, 75205, Paris cedex 13, France
⁵ St. Petersburg Nuclear Physics Institute, 188300, Gatchina, Russia
⁶ RRC Kurchatov Institute, Kurchatov Sq.1, 123182, Moscow, Russia
⁷ Joint Institute for Nuclear Research, Joliot Curie 6, 141980, Dubna, Moscow region, Russia
⁸ INFN Laboratori Nazionali del Gran Sasso, SS 17 bis Km 18+910, 67010, Assergi (AQ), Italy
⁹ Technische Universität München, James Franck Strasse, E15, 85747, Garching, Germany
¹⁰ Physics Department, Virginia Polytechnic Institute and State University, Roberson Hall, Blacksburg, VA, 24061-0435, USA
¹¹ Kiev Institute for Nuclear Research, 47 Prospekt Nauki, 06380, Kiev, Ukraine
¹² Dipartimento di Fisica Università and I.N.F.N. Genova, Via Dodecaneso 33, 16146, Genova, Italy
¹³ Dipartimento di Chimica Università di Perugia, Via Elce di Sotto 8, 06123, Perugia, Italy
¹⁴ M. Smoluchowski Institute of Physics, Jagellonian University, ul. Reymonta 4, 30059, Krakow, Poland
¹⁵ Max-Planck-Institut für Kernphysik, Postfach 103 980, 69029, Heidelberg, Germany

^* e-mail: derbin@pnpi.spb.ru

Received: 20 August 2007
Published online: 29 January 2008

Abstract

Results of background measurements with a prototype of the Borexino detector were used to search for 478 keV solar axions emitted in the M1-transitions of ⁷Li^*. The Compton conversion of axion to a photon A+e→e+γ, axioelectric effect A+e+Z→e+Z, decay of axion in two photons A→2γ and Primakoff conversion on nuclei A+Z→γ+Z are considered. The upper limit on constants of interaction of axion with electrons, photons and nucleons – g_Aeg_AN≤(1.0–2.4)×10^-10 at m_A≤450 keV and g_Aγg_AN≤5×10^-9 GeV^-1 at m_A≤10 keV are obtained (90%c.l.). For heavy axions with mass at 100<m_A<400 keV the limits g_Ae<(0.7–2.0)×10^-8 and g_Aγ<10^-9–10^-8 are obtained in assumption that g_AN depends on m_A as for KSVZ axion model. These limits are stronger than obtained in previous laboratory-based experiments using nuclear reactor and artificial radioactive sources.