Alpha decay of Europium isotopes

Abstract

-Pioneer experimental indication of an extremely low alpha activity due to 151 Eu isotope (equivalent to ∼10-70 disintegrations/h-kg of nat Eu) is discussed in the framework of a simple, one-parameter model to alpha transitions developed by us recently.The present evaluated alpha activity is found equivalent to ∼18 disintegrations/h-kg, in excellent agreement with the observed decay rate. Partial alpha decay half-life evaluations for 147−153 Eu isotopes are also reported.

Discovery of the $^{151}$Eu $α$ decay

“…(3) This value is in agreement with half-life interpreted from the indication of 151 Eu α decay reported in [14]. Our measurement concurs, within 1 σ with the theoretical prediction using the Coulomb and proximity potential model reported in [5], and is not compatible with the semi-empirical calculation reported in [3,24,25].…”

“…Modern calculations of the partial half-lives of 147,148,150,151,153 Eu mainly follow two approaches, namely the semi-empirical one [3], developed in [4] and the Coulomb and proximity potential model (CPPM) [5], proposed in [6]. The results obtained by the two approaches for the half-life of 151 Eu range between 8.5×10 18 y [3] using semi-empirical calculations and 8.0×10 17 y [5] using CPPM for deformed nuclei (CPPMDN).…”

Discovery of the151Eu α decay

“…This value is in agreement with half-life interpreted from the indication of 151 Eu α decay reported in [14]. Our measurement concurs, within 1 σ with the theoretical prediction using the CPPM reported in [5], and is not compatible with the semi-empirical calculation reported in [3,24,25].…”

“…The Li 6 Eu(BO 3 ) 3 crystal was operated in a dilution 3 He/ 4 He refrigerator in the Gran Sasso underground laboratory of INFN. The crystal was held in position by means of a high-purity copper structure.…”

“…Modern calculations of the partial half-lives of 147,148,150,151,153 Eu mainly follow two approaches, namely the semi-empirical one [3], developed in [4] and the Coulomb and proximity potential model (CPPM) [5], proposed in [6]. The results obtained by the two approaches for the half-life of 151 Eu range between 8.5 × 10 18 y [3] using semi-empirical calculations and 8.0 × 10 17 y [5] using CPPM for deformed nuclei (CPPMDN).…”