A. Ljubičić

SEARCH FOR SOLAR AXIONS USING 57FE

Abstract We have made a search for 57 Fe gamma rays of energy 14.4 keV induced by resonant absorption of monochromatic solar axions, as proposed by Moriyama. The proposed axions are suggested to be emitted from the Sun, in M1 transitions between the first, thermally excited state and the ground state of 57 Fe. An upper limit on hadronic axion mass of 745 eV is obtained at the 95% confidence level, it being assumed that z =0.56 and S =0.5.We have made a search for Fe-57 gamma rays of energy 14.4 keV induced by resonant absorption of monochromatic solar axions, as proposed by Moriyama. The proposed axions are suggested to be emitted from the Sun, in M1 transitions between the first, thermally excited state and the ground state of Fe-57. An upper limit on hadronic axion mass of 745 eV is obtained at the 95% confidence level, it being assumed that z=0.56 and S=0.5.

Search for invisible axions using Fe-57

Abstract We have made a search for 57 Fe gamma rays of energy 14.4 keV induced by resonant absorption of monochromatic solar axions, as proposed by Moriyama. The proposed axions are suggested to be emitted from the Sun, in M1 transitions between the first, thermally excited state and the ground state of 57 Fe. An upper limit on hadronic axion mass of 745 eV is obtained at the 95% confidence level, it being assumed that z =0.56 and S =0.5.We have made a search for Fe-57 gamma rays of energy 14.4 keV induced by resonant absorption of monochromatic solar axions, as proposed by Moriyama. The proposed axions are suggested to be emitted from the Sun, in M1 transitions between the first, thermally excited state and the ground state of Fe-57. An upper limit on hadronic axion mass of 745 eV is obtained at the 95% confidence level, it being assumed that z=0.56 and S=0.5.

A new look at nuclear excitation in an electron transition

Abstract The mechanism for nuclear excitation in an electron transition (NEET) has been reanalyzed. In contrast to other calculations our analysis shows that the NEET process probability does not depend on the details of the nuclear transition but rather on the properties of the electron states. Our predictions are in very good agreement with the available experimental data.

Search for hadronic axions using axioelectric effect

Abstract We made a search for hadronic axions which could be emitted from the Sun in M1 transitions between the first 14.4 keV thermally excited and the ground state in 57Fe, and absorbed in the HPGe detector by axioelectric effect. An upper limit on hadronic axion mass of 400 eV is obtained at the 95% confidence level.

Search for solar hadronic axions produced by a bremsstrahlung-like process

Abstract We have searched for hadronic axions which may be produced in the Sun by a bremsstrahlung-like process, and observed in the HPGe detector by an axioelectric effect. A conservative upper limit on the hadronic axion mass of m a ≲ 334 eV at 95% C.L. is obtained. Our experimental approach is based on the axion–electron coupling and it does not include the axion–nucleon coupling, which suffers from the large uncertainties related to the estimation of the flavor-singlet axial-vector matrix element.

Constraining solar hidden photons using HPGe detector

Abstract In this Letter we report on the results of our search for photons from a U(1) gauge factor in the hidden sector of the full theory. With our experimental setup we observe the single spectrum in a HPGe detector arising as a result of the photoelectric-like absorption of hidden photons emitted from the Sun on germanium atoms inside the detector. The main ingredient of the theory used in our analysis, a severely constrained kinetic mixing from the two U(1) gauge factors and massive hidden photons, entails both photon into hidden state oscillations and a minuscule coupling of hidden photons to visible matter, of which the latter our experimental setup has been designed to observe. On a theoretical side, full account was taken of the effects of refraction and damping of photons while propagating in Sunʼs interior as well as in the detector. We exclude hidden photons with kinetic couplings χ > ( 2.2 × 10 − 13 – 3 × 10 − 7 ) in the mass region 0.2 eV ≲ m γ ′ ≲ 30 keV . Our constraints on the mixing parameter χ in the mass region from 20 eV up to 15 keV prove even slightly better then those obtained recently by using data from the CAST experiment, albeit still somewhat weaker than those obtained from solar and HB stars lifetime arguments.

A generalized figure of merit for gamma-ray polarimeters

Abstract A figure of merit, which can be applied in general situations, is proposed for gamma-ray polarimeters. An increase in the figure merit for a polarimeter gives a proportional decrease in the time necessary to achieve a given statistical accuracy. Various existing gamma-ray polarimeters are considered using the figure of merit as a basis for comparison.

Hunting up low-mass bosons from the Sun using HPGe detector

Abstract In this experiment we aim to look for keV-mass bosons emitted from the Sun, by looking at a process analogous to the photoelectric/Compton effect inside the HPGe detector. Their coupling to both electrons and nucleons is assumed. For masses above 25 keV, the mass dependence of our limit on the scalar-electron coupling reveals a constraint which proves stronger than that obtained recently and based on the very good agreement between the measured and predicted solar neutrino flux from the 8 B reaction. On the other hand, the mass dependence of our limit on the scalar-proton/electron coupling together entails a limit on a possible Yukawa addition to the gravitational inverse square low. Such a constraint on the Yukawa interactions proves much stronger than that derived from the latest AFM Casimir force measurement.

Experimental and theoretical investigations of double internal bremsstrahlung in electron capture

Abstract Experimental and theoretical investigations have been made of double internal bremsstrahlung in electron capture. The decay of 37 Ar was studied at lower energies than in the earlier investigations and the calculations were extended to allow for the contributions of 2s, 2p and 3p initial electron states, as well as those of the 1s electron states.

The mechanism for pair production in the α-Decay of241Am

The mechanism for pair production in the α-decay of241Am is discussed. The pair creation is dominantly involved with the dynamics of the α-decay process and contributions from237Np levels with energies >2mc2 are relatively small. One of the authors (B.A.L.) would like to thank the Natural Sciences and Engineering Council of Canada for financial support.