Newβ-delayed proton precursor135Gd

Unknownβ-delayed proton precursor¹³⁵Gd has been synthesized by the reaction¹⁰⁶Cd (³²S, 3n) and identified using a helium-jet recoil fast tape-transport system with aγ(X)-p coincidence measurements. Itsβ-delayed proton spectrum has been observed. The half-life of¹³⁵Gd decay has been determined to be 1.1±0.2 s.     

New β-delayed proton precursor 135Gd

Unknown β-delayed proton precursor ¹³⁵Gd has been synthesized by the reaction ¹⁰⁶Cd ( ³²S, 3n ) and identified using a helium-jet recoil fast tape-transport system with a γ(X)-p coincidence measurements. Its β-delayed proton spectrum has been observed. The half-life of ¹³⁵Gd decay has been determined to be 1.1 ± 0.2 s.     

Theβ + decay of the new isotope86Mo and the first observation of86m Nb

Theβ ⁺ decay of⁸⁶Mo has been firstly investigated by means ofβγ spectroscopy. The⁸⁶Mo nuclei were produced by fusion-evaporation reactions of⁵⁴ Fe (³⁵Cl, 1 p2n) and⁵⁸Ni (³²S,2p 2n) at beam energies of 103 and 120 MeV, respectively. Threeγ rays of 47.3, 49.8 and 187.0 keV were unambiguously identified to follow theβ ⁺ decay of⁸⁶Mo by results ofXγ andβγ coincidence and cross-bombardment. A half life and a maximumβ ⁺-ray energy of⁸⁶Mo were determined to be 19.6±1.1 s and 3.9±0.4 MeV, respectively. A decay scheme of⁸⁶Mo is proposed in this article. Furthermore, a decay of⁸⁶Nb has been studied using the same combinations of projectiles and targets, and a newβ-decaying isomer^86m Nb was observed with a half life of 56.3±8.3 s.     

Decay properties of neutron deficient Kr isotopes

The decay properties of the neutron deficient isotopes^73–77Kr and^73–76Br have been studied at the ISOLDE facility at CERN. The total decay energiesQ, as determined fromβ ⁺ singles orβ ⁺ -γ coincidence measurements, are compared with mass formulae.     

The decay of 4 min 158Tm

The decay of 4 min ¹⁵⁸Tm has been investigated with on-line mass-separated samples obtained from the Orsay ISOCELE separator. Measurements of γ-rays, conversion electron lines and γ-γ bi-dimensional coincidences were performed. About 180 transitions were ascribed to the decay and two thirds of them were placed in a decay scheme. The β-band and the γ-band were identified with bandheads situated at 806.40 and 820.13 keV respectively. In addition, a number of other vibrational bands (β-γ, β-β, K^π = 0^? and 1^?) are proposed. The decay properties of those bands are discussed in the framework of current nuclear models. The log ft values suggest a 2^? assignment for ¹⁵⁸Tm with the possible configuration (p404J↓-n521↑).     

The spectroscopy of 22Al: a βp, β2p and βα emitter

In an experiment at the LISE3 facility of GANIL, we produced the proton-rich isotope ²²Al by the fragmentation of a ³⁶Ar primary beam at 95 MeV/nucleon. After implantation in a detector telescope, the decay of ²²Al via β-delayed proton emission, β-delayed two-proton emission as well as, for the first time, via β-delayed α emission has been studied. An α peak has been observed at (3.27 ± 0.04) MeV with a branching ratio of (0.31 ± 0.09) %. The comparison of the different decay channels to those of the mirror nucleus ²²F and to shell-model calculations favor a 3⁺ state as being the ground state of ²²Al. A half life of T_1/2 = (59 ± 3) ms has been measured.     

The level scheme of91Tc and theβ decay of91Ru(9/2+)

The level scheme of⁹¹Tc has been studied by means of in-beamγ-ray spectroscopy in the irradiations of⁵⁸Ni and⁵⁴Fe targets by⁴⁰Ca beams from the Munich MP tandem and the heavy ion post accelerator. A large number of positive as well as of negative parity yrast-levels with excitation energies up to 8 MeV has been established. The level scheme of⁹¹Tc has been compared with shell model claculations and a good agreement for all identified levels has been found. In parallel investigations of the residual activities of the reaction⁴⁰Ca→⁵⁴Fe, theβ decay of the (9/2⁺ ground) state of⁹¹Ru has been investigated. Aβ decay scheme of⁹¹Ru(9/2⁺) has been established. The half-life of⁹¹Ru(9/2⁺) has been measured to be 9±1 s.     

The half-life for the superallowed fermi beta decay 50Mn(β+)50Cr

The half-life for the decay ⁵⁰Mn(β⁺)⁵⁰Cr has been measured to be 282.8 ± 0.3 ms. This result is ≈ 1% lower than the accepted value. It would bring the ft value for ⁵⁰Mn decay into agreement with recent measurements for other superallowed Fermi decays.     

Nuclear spectroscopic studies of the 23.7 h 248Bk

Main features of the decay of the 23.7 h ²⁴⁸Bk have been determined by spectroscopy with scintillation and semiconductor detectors. The results are as follows: half-life 23.7 ± 0.2 h; branching is (30 ± 5)% to ²⁴⁸Cm (≈ 23% EC decay to 0⁺ ground state and ≈ 7% to first 2⁺ state) and (70 ± 5)%β^? decay to ²⁴⁸Cf(5 % to 592 keV K^π = 2^? state and (65 ± 5)% to the ground-state band). The β^? decay energy, Q_β^?, has been measured to be 860 ± 20 keV, and the electron capture decay energy, Q_EC, has been derived from closed cycle to be 705 ± 25 keV. The deduced logft values of β^? and EC transitions restrict the spin of the ²⁴⁸Bk ground state to 1, with configuration assignment $\text{{}\text{n}\text{[734]}\text{9}\text{2}{}^{\mathrm{?}}$; $\text{p}\text{[633]}\text{7}\text{2}{}^{\mathrm{+}}$. It has also been deduced that the long lived isomer lies 65 ± 40 keV abovethe 23.7h ²⁴⁸Bk ground state.     

Das Positronenspektrum von22Na und die Ruhemasse des Neutrinos aus dem β+-Zerfall

Theβ ⁺ spectrum of²²Na has been measured with the Heidelberg (π/2) √13 iron-freeβ-ray spectrometer. Particular attention was paid to the upper end of the continuum. The maximum energy was found to beE _max=(545.7 ±0.5) keV. The rest mass of the neutrino connected withβ ⁺ decay was found to be zero with an upper limit of 4.1 keV (67 per cent confidence).     

The decay of136Te (20.9 s)

The beta decay of¹³⁶Te has been investigated with the on-line mass separator LOHENGRIN from the Institute Laue-Langevin at Grenoble in conjunction with an air-jet collecting system. A level scheme of¹³⁶I based on coïncidence measurements has been established. The measuredQ _β value is 5100±150 keV.     

Decay of neutron-rich Ga isotopes near N = 50 at PARRNe

The PARRNe facility has been used to produce neutron-rich isotopes ^83,84Gaby the ISOL method. Their decay has been studied, and β-γ coincidence and γ-γ coincidence data were collected as a function of time. The first two excited levels in ⁸³Ge and the first excited level in ⁸⁴Ge have been measured for the first time.     

Beta delayed proton emission from the 14s 21/2+ spin gap isomer in95Pd

The residual activities of the projectile-target system⁴⁰Ca→⁵⁸Ni have been investigated with gamma and proton multi spectrum analyses,γγ andpγ coincidences. Aβ decaying high-spin isomer in⁹⁵Pd withJ ^π=(21/2⁺), a half-life of 14±1 s and an excitation energy of about 2 MeV has been identified. It has been found that⁹⁵Pd ^m is aβ delayed proton precursor. The totalβ branching to proton emitting states has been determined to be (0.74±0.19)·10^?2. It has been observed that the final state in⁹⁴Ru, populated after proton emission, is dominantly the 8⁺ state. A decay scheme of⁹⁵Pd ^m has been derived.     

Effect of synchrotron radiation on nuclear beta decay

The stimulation of the endothermic beta decay of stable nuclei by the field of synchrotron radiation has been analyzed theoretically in the framework of the photobeta decay mechanism. In contrast to works devoted to the effect of laser fields on beta decay, the action of the field directly on a nucleus rather than on a beta electron is considered (a sufficiently intense flux of hard photons whose energies exceed 60 keV allows this action). The rates of such a beta decay are calculated for a number of “parent nucleus-daughter nucleus” pairs for the relativistic case including Coulomb effects. For the most intense available sources of synchrotron radiation, the rate of stimulated beta decay for most nuclei under investigation appears to be characteristic of third-forbidden β^? transitions. The effect of synchrotron radiation on highly forbidden natural nuclear β^? decays is also analyzed. In particular, irradiation increases the rate of the β^? decay of the ₃₇ ⁸⁷ Rb and ₄₉ ¹¹⁵ In nuclei by 2% and by almost two orders of magnitude, respectively.     

Measurement of the nuclear magnetic moment of110Ag(T 1/2=24.4 s)

Nuclear magnetic resonance of¹¹⁰Ag has been observed in silver halides using the polarized neutron capture,β decay anisotropy method. The magnetic moment was determined asμ _I(¹¹⁰Ag)=2.7084 (5) nm (uncorrected).     

Decay of90m,g Rb

The decay of mass separated⁹⁰Rb has been studied usingβ,γ and conversion electron spectrometers in single and coincidence modes. The half-lives of the ground state and the isomeric level have been confirmed to be 162± 3 and 258±4 s, respectively. Theγ-rays from the decays of ground state and metastable state have been identified by measuring the decay of individual photopeaks using Ge(Li) detectors. The multipolarity of the 106.6 keV isomeric transition has been determined to beM3. Separate decay schemes of the ground and metastable states are presented. The levels of⁹⁰Sr are discussed in terms of the available experimental and theoretical information. Radioactivity.^90m,gRb [from²³⁸U(p, f)]; measuredT _1/2,E _γ,I _γ,γ—γ coin,I _ce,cc,E _β deduced logft,⁹⁰Sr levels, mass separated⁹⁰Rb.     

The decay of 20 min179Re

The decay of 20 min¹⁷⁹Re has been studied by means of Ge(Li) and Si(Li) detectors and a magneticβ-ray spectrometer. From the measured positon endpoint aQ-value of 2690±50 keV has been deduced. The decay scheme given is supported by coincidence relations. Fast beta transitions (logft≈5.1) to levels at 720keV and 1680 keV in¹⁷⁹W can be explained by a three quasi-particle character for these states. Nilsson assignments to these and other levels are discussed.     

Der Zerfall des Lu176m

The decay of Lu^176m has been investigated. TheK-conversion coefficient α _K of the 88,3 keV niveau of Hf¹⁷⁶ has been determined to α _K =1,35±0,07. Theβ-branching ratio to the 0+ and 2+ niveau of Hf¹⁷⁶ has been measured by means of aβ-γ-coincidental technique. (60,4±6,1)% of Lu^176m decay into the 2+ niveau and (39,6±6,1)% into the 0+ niveau of Hf¹⁷⁶.K-capture of Lu^176m to Yb¹⁷⁶ was not found. If there is any, it is less than 0,1% of all decays.