Status and Perspectives of 2ϵ, ϵβ+ and 2β+ Decays

Belli, P.; Bernabei, R.; Caracciolo, V.

doi:10.3390/particles4020023

Cited by 14 publications

(13 citation statements)

References 237 publications

(475 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, to further increase the sensitivity for the study of the rare α and 2β decays of naturally occurred hafnium isotopes with the active source approach, it is also relevant to improve the radiopurity of Cs 2 HfCl 6 crystal scintillators, in particular for what concerns the Sm component in traces. [1,27]. The α decay of 174 Hf has been observed [27], while only lower limits at 90% C.L.…”

Section: Perspectives and Conclusionmentioning

confidence: 93%

“…Thus, the 0νDBD is of great interest because it could open a new window beyond the Standard Model. The number of candidate isotopes to this study are 69, in particular, 35 via the emission of two e − and 34 in positive channels: either two positron emission (2β + ) or a positron emission with an electron capture ( β + ) or a double electron capture (2 ) [1,2]. The simultaneous study of positive and negative DBD can constrain the theoretical parameters with very high confidence, giving mutual information.…”

Section: Introductionmentioning

confidence: 97%

“…The simultaneous study of positive and negative DBD can constrain the theoretical parameters with very high confidence, giving mutual information. Additionally, the nuclear matrix elements for the 2ν transition and 0ν transition can be connected through significant parameters: in the free nucleon interaction, the g A value is 1.2701, but, considering a nuclear decay, the phenomenological axial-vector coupling value seams reduced to g A < 1, more precisely: g A ∼ 1.269A −0.12 or g A ∼ 1.269A −0.18 , depending on the adopted nuclear model [1]. Moreover, the "quenched" g A observed is shown to encode the emergence of chiral-scale symmetry hidden in QCD in the vacuum; the g A value could impact the in-medium modified nucleon weak and electromagnetic form factors on the neutrino mean free path in dense matter; the g A role in the values of the cross sections of neutrino scattering from astrophysical sources on nuclei; and many other issues.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, DBD investigation considering different nuclei would help to constrain these and other significant model-dependent parameters. In addition, in case of the 0ν2 transition, it is possible to study also the so-called "resonant effect" [1,2].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Investigation on Rare Nuclear Processes in Hf Nuclides

et al. 2022

Self Cite

View full text Add to dashboard Cite

In this work, a review of recent studies concerning rare nuclear processes in Hf isotopes is presented. In particular, the investigations using HP-Ge spectrometry and Hf-based crystal scintillators are focused; the potentiality and the results of the “source = detector” approach are underlined. In addition, a short introduction concerning the impact of such kind of research in the context of astroparticle and nuclear physics is pointed out. In particular, the study of α decay and double beta decay of 174Hf, 176Hf, 177Hf, 178Hf, 179Hf, 180Hf isotopes either to the ground state or to the lower bounded levels have been discussed. The observation of α decay of 174Hf isotope to the ground state with a T1/2=7.0(1.2)×1016 y is reported and discussed. No decay was detected for α decay of 174Hf isotope at the first excited level of daughter and of 176Hf, 177Hf, 178Hf, 179Hf, 180Hf isotopes either to the ground state or to the lower bounded levels. The T1/2 lower limits for these decays are at the level of 1016–1020 y. Nevertheless, the T1/2 lower limits for the transitions of 176Hf→172Yb (0+→0+) and 177Hf→173Yb (7/2−→5/2−) are near to the theoretical predictions, giving hope to their observation in the near future. All the other experimental limits (∼1016–1020 y) are absolutely far from the theoretical expectations. The experiments investigating the 2ϵ and ϵβ+ processes in 174Hf are also reported; the obtained half-life limits are set at the level of 1016–1018 y. Moreover, we estimate the T1/2 of 2ν2ϵ of 174Hf decay at the level of (0.3–6) × 1021 y (at now the related measured lower limit is 7.1×1016 y).

show abstract

Section: Perspectives and Conclusionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Investigation on Rare Nuclear Processes in Hf Nuclides

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…Double beta decay (DBD) is a secondorder allowed process in the Standard Model and β − β − decay mode has been detected in several nuclei. However, positron decay modes are hindered due to lower effective Q value [2] and experimental search for β + β + /EC-β + continues to be elusive. An important experimental signature of the decay modes involving positrons like EC-β + and β + β + is the simultaneous emission of pair(s) of 511 keV gamma rays.…”

Section: Introductionmentioning

confidence: 99%

Background Estimation Studies for Positron Double Beta Decay

Thakur¹,

Mazumdar²,

Shah³

et al. 2021

Preprint

View full text Add to dashboard Cite

The study of neutrinoless double beta decay has attracted much attention as it can provide valuable information about the mass and the nature of the neutrino. The double beta decay (DBD) itself is also of interest in nuclear physics. While DBD has been observed in about a dozen nuclei, the positron double beta decay (β + β + /EC-β + ) continues to be an elusive. An important signature for β + β + decay is the simultaneous emission of four 511 keV gamma rays and the coincident detection of these gamma rays can improve the measurement sensitivity. This paper presents an estimation of sensitivity for EC-β + and β + β + employing coincidence measurement with two high purity Ge (HPGe) detectors. Simulations for coincident detection efficiency (ǫ c ) of 511 keV gamma rays with two HPGe detectors have been carried out using GEANT4 for different source geometries to optimize the mass efficiency product (Mǫ c ). The source of size 55 mm × 55 mm × 5 mm (thickness) sandwiched between the front faces of the detectors were found to be optimal for 2 pairs of 511 keV gamma rays in the present detector setup. The coincident background is estimated at the sea level with moderate Pb shielding. With this setup, the sensitivity for T 1/2 measurement of EC-β + in 112 Sn and β + β + in 106 Cd is estimated to be ∼ 10 19 -10 20 y for 1 y of measurement time.

show abstract