Search results for "beta"

Forbidden nonunique β decays and effective values of weak coupling constants

2016

Forbidden nonunique β decays feature shape functions that are complicated combinations of different nuclear matrix elements and phase-space factors. Furthermore, they depend in a very nontrivial way on the values of the weak coupling constants, gV for the vector part and gA for the axial-vector part. In this work we include also the usually omitted second-order terms in the shape functions to see their effect on the computed decay half-lives and electron spectra (β spectra). As examples we study the fourth-forbidden nonunique ground-state-to-ground-state β− decay branches of 113Cd and 115In using the microscopic quasiparticle-phonon model and the nuclear shell model. A striking new feature …

β-decay half-life of V 50 calculated by the shell model

2014

In this work we survey the detectability of the β− channel of 50 23V leading to the first excited 2+ state in 50 24Cr. The electron-capture (EC) half-life corresponding to the transition of 50 23V to the first excited 2+ state in 50 22Ti had been measured earlier. Both of the mentioned transitions are 4th-forbidden non-unique. We have performed calculations of all the involved wave functions by using the nuclear shell model with the GXPF1A interaction in the full f-p shell. The computed half-life of the EC branch is in good agreement with the measured one. The predicted half-life for the β− branch is in the range ≈2 × 1019 yr whereas the present experimental lower limit is 1.5 × 1018 yr. We…

Penning-trap-assisted study of excitations in $^{88}$Br populated in β decay of $^{88}$Se

2017

Excited levels of 88Br populated in the β decay of 88Se have been studied by means of βγ and γ γ spectroscopy methods. Neutron-rich parent 88Se nuclei were produced with proton-induced fission of 238U using the Ion Guide Isotope Separator On-Line (IGISOL) method and separated from contaminants using a dipole magnet and the coupled JYFLTRAP Penning trap at the Accelerator Laboratory of the University of Jyvaskyl ¨ a. The level scheme ¨ of 88Br has been constructed and log f t values of levels were determined. The ground-state spin of 88Br is now firmly determined to be 1−. Low-energy levels in 88Br were interpreted as members of the πp3/2(νd5/2) 3, πp−1 3/2(νd5/2) 3, πf −1 5/2 (νd5/2) 3, and…

Identification of the crossing point at N=21 between normal and intruder configurations

2017

The β− decay of 34Mg was used to study the 34Al nucleus through γ spectroscopy at the Isotope Separator OnLine facility of CERN. Previous studies identified two β-decaying states in 34Al having spin-parity assignments J π = 4− dominated by the normal configuration π(d5/2) −1 ⊗ ν(f7/2) and J π = 1+ by the intruder configuration π(d5/2) −1 ⊗ ν(d3/2) −1(f7/2) 2. Their unknown ordering and relative energy have been the subject of debate for the placement of 34Al inside or outside the N = 20 “island of inversion.” We report here that the 1+ intruder lies only 46.6 keV above the 4− ground state. In addition, a new half-life of T1/2 = 44.9(4) ms, that is twice as long as the previously measured 20…

Impact of the quenching of gA on the sensitivity of 0νββ experiments

2017

Detection of the neutrinoless ββ (0νββ) decay is of high priority in the particle- and neutrino-physics communities. The detectability of this decay mode is strongly influenced by the value of the weak axial-vector coupling constant gA. The recent nuclear-model analyses of β and ββ decays suggest that the value of gA could be dramatically quenched, reaching ratios of gfree A /gA ≈ 4, where gfree A = 1.27 is the free, neutron-decay, value of gA. The effects of this quenching appear devastating for the sensitivity of the present and future 0νββ experiments since the fourth power of this ratio scales the 0νββ half-lives. This, in turn, could lead to some two orders of magnitude less sensitivit…

Second-forbidden nonunique β− decays of 24Na and 36Cl assessed by the nuclear shell model

2020

We have performed a systematic study of the log f t values, shape factors, and electron spectra for the second-forbidden nonunique β− decays of 24Na(4+) →24Mg(2+) and 36Cl(2+) →36Ar(0+) transitions under the framework of the nuclear shell model. We have performed the shell model calculations in the sd model space, using more recent microscopic effective interactions such as Daejeon16, chiral N3LO, and JISP16. These interactions are derived from the no-core shell model wave functions using Okubo-Lee-Suzuki transformation. For comparison, we have also shown the results obtain from the phenomenological USDB interaction. To test the predictive power of these interactions first we have computed …

Total absorption γ-ray spectroscopy of the β decays of 96gs,mY

2022

The β decays of the ground state (gs) and isomeric state (m) of 96Y have been studied with the total absorption γ-ray spectroscopy technique at the Ion Guide Isotope Separator On-Line facility. The separation of the 8+ isomeric state from the 0− ground state was achieved thanks to the purification capabilities of the JYFLTRAP double Penning trap system. The β-intensity distributions of both decays have been independently determined. In the analyses the deexcitation of the 1581.6 keV level in 96Zr, in which conversion electron emission competes with pair production, has been carefully considered and found to have significant impact on the β-detector efficiency, influencing the β-intensity di…

In vitro digestion of beta glucan enriched pasta and antioxidant potential of digesta

2014

Purification and characterization of an intracellular family 3 β-glucosidase from Lactobacillus sanfranciscensis CB1

2005

Lactobacillus sanfranciscensis CB1 uses cellobiose and other β-glucosides (methyl-β-glucoside, arbutin, amygdalin and salicin) as carbon sources. A hexameric ca. 288 kDa β-glucosidase was purified to homogeneity from Lact. sanfranciscensis CB1 by four chromatographic steps. The enzyme was optimally active at pH 7.5 and 40°C. It had a pI of ca. 4.38 and a D55°C value of ca. 27 sec. Almost total inhibition was found with sulfhydryl-modifying agents and divalent cations such as Cu2+, Co2+, Hg2+, Ni2+ and Fe2+ at a concentration of 2 mM. The enzyme was active towards β-(1→4) substrates such as p-nitrophenyl-β-D-glucoside, -D-galactoside and -L-rhamnoside, and cellobiose. The sequencing of four …

Produktivitātes konverģences tendences Latvijas uzņēmumu līmenī

2020

Maģistra darbs ir veltīts Latvijas uzņēmumu produktivitātes konverģencei periodā no 2010. līdz 2018. gadam. Galvenais datu avots ir ORBIS datubāze, kas apkopoja mikrodatus par vidēji 145 121 uzņēmumiem katru gadu. Darba ietvaros uzņēmuma produktivitāte ir definēta kā reālā pievienotā vērtība uz vienu darbinieku. Izmantojot gan šķērsgriezuma, gan paneļu datu modeļus, tika apstiprināta produktivitātes absolūtā Beta konverģence starp Latvijas uzņēmumiem. Konverģence ātrums atkarībā no šķērsgriezuma modeļiem ir no 2.56% līdz 2.79% gadā, bet tajā pat laikā tika secināts izkliedes palielinājums starp uzņēmumu produktivitātes līmeņiem, kas liecina par sigma-diverģenci. Papildinot regresijas modeļu…