Beta-decay properties of 25 Si and 26 P

Abstract

The β-decay properties of the neutron-deficient nuclei 25 Si and 26 P have been investigated at the GANIL/LISE3 facility by means of charged-particle and γ-ray spectroscopy. The decay schemes obtained and the Gamow-Teller strength distributions are compared to shell-model calculations based on the USD interaction. B(GT ) values derived from the absolute measurement of the β-decay branching ratios give rise to a quenching factor of the Gamow-Teller strength of 0.6. A precise half-life of 43.7 (6) ms was determined for 26 P , the β −(2)p decay mode of which is described.PACS. 29.30.Ep Charged-particle spectroscopy -29.30.Kv X-and gamma-ray spectroscopy -23.90.+w

Resonances above the proton threshold inSi26

“…Accounting for the new value of S p = 5513.8 keV, the 412 keV resonance energy measured by Thomas et al [17] produces an excitation energy of 5925.8 keV, reduced from 5929 keV. In the proton decay Q value measurement of Peplowski et al [26], the shift in S p results in a new E x of 5873.8 keV, reduced from 5878 keV (this E x is not reported explicitly, but is calculated from the reported Q = 0.36 MeV and S p = 5518 keV which the measurement adopts).…”

“…Resonance D has, by far, received the most attention [6,15,17,18,21,24,26,28,29]. These measurements have generally converged on the spin assignment of this level being 3 + ; those measurements with a particular sensitivity to this important ℓ = 0 resonance have verified this assignment beyond a reasonable doubt [6,17,26,29] (see also Section III D).…”

“…The majority of works [15, 16, 18, 20-22, 24, 26] adopted the old value of S p = 5518 keV or something close to it; several [27,29,30,32,33] adopted the newer value of 5513.7 keV from Ref. [37], a 4.3 keV difference; the remainder adopted differing values (5517 [17], 5513 [19], 5512.3 [25,28], and the AME2012 value of 5513.8 [6]) or do not mention any value for S p [13,14].…”

“…26 P decay [17] and 25 Al(d,n) [26]. In these two measurements, the resonance energy (or decay Q value) was measured directly, but in each the adopted proton threshold S p differs from the updated, most precise value [37,41].…”

26Si excited states via one-neutron removal from a27Si radioactive ion beam

“…Since a direct measurement of the 25 Al(p,γ) 26 Si reaction is presently untenable due to insufficiently intense beams of 25 Al, transfer reactions and in-beam gamma-ray spectroscopic studies have been used extensively to determine indirectly the important level properties of 26 Si, such as resonance energies and spin-parity assignments [1,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. The rate has been re-evaluated recently [23,[26][27][28], and Ref.…”