Decay of the 55 min and 12 min Te isomers

Gamma rays emitted in the decay of the ¹³³Te isomers, 55.4 min ^133mTe and 12.5 min ^133gTe, have been observed with Ge(Li) detectors. Sources were prepared by separating Sb from fission products, allowing several minutes for decay of 2.7 min ¹³³Sb and then separating the Te daughter activities. A total of 29 γ-rays between 312 and 2541 keV were attributed to decay of ^133gTe and 30 from 74 to 2050 keV to that of ^133mTe. Gamma-gamma coincidences in the decay of ^133gTe were observed with a NaI(Tl)---Ge(Li) set-up. The decay scheme of ^133gTe was constructed, involving placement of 25 of the γ-rays emitted. The decay of ^133gTe populates levels in ¹³³I at 0, 312, 720, 787, 1313, 1333, 1374, 1565, 1718, 2137, 2194 and 2541 keV. The decay of ^133mTe is very complicated, and we have not attempted construction of a complete decay scheme for it; however, levels at 913 and 1561 keV in ¹³³I are definitely populated in ^133mTe decay. The value for Q_β of ¹³³Te was measured as 3.52±0.10 MeV. The low-lying levels of the odd-mass iodine isotopes vary smoothly through the series ¹²⁵I through ¹³³I. The levels of ¹³³I are fitted rather well by predictions based on quasi-particle-phonon coupling.     

Two-quasiparticle states in Ho

Thirty-one levels in ¹⁶⁴Ho have been observed up to an excitation energy of 994 keV utilizing 12 MeV deuterons and the reaction ¹⁶⁵Ho(d, t)¹⁶⁴Ho. The ground state Q-value was determined to be −1730±15 keV. The spectrum has been interpreted in terms of the coupling of the [523↑] Nilsson proton orbital with the neutron orbitals prominent in the (d, t) spectrum of ¹⁶³Dy. Based on this interpretation, the singlet-triplet splitting energies for the [523↓], [642↑], [521↑], [402↓] and [400↑] neutron orbitals coupled to the [523↑] proton orbital were determined to be −144, +67, +171, −85 and +102 keV, respectively. Theoretical calculations of these energies made for a zero-range spin-dependent central potential gave values of −248, +74, +160, −82 and +73 keV, respectively.     

Rotational bands in Ho

The excited states of the deformed odd-proton nucleus ¹⁶¹Ho have been studied in the reactions ¹⁵⁹Tb(, 2n), ¹⁶¹Dy(d, 2n) and ¹⁶¹Dy(p, n). Gamma-ray spectra in single and coincidence modes as well as angular distributions and excitation functions of the transitions were measured. The proposed level scheme of ¹⁶¹Ho contains besides of the ground state band ⁻[523] the bands ⁺[404], ⁺[411], ⁺[411] and ⁻ [541] (band heads at 252.7, 298.7, 211.2 and 423.9 keV, respectively). An attempt was made to estimate the influence of Coriolis coupling between the bands ⁺ [411] and ⁺ [411], which are very close in energy. The ⁺ [404] band was found to de-excite by very fast E1 transitions to the ground state band ⁻[523]. Nilsson retardation factors of about 0.03 for these transitions were deduced using the E2/E1 branching ratios. An investigation has also been made of the independent feeding of the levels from high-lying states.     

The decay of Se

The gamma-ray spectrum associated with the electron capture decay of ⁷⁵Se has been studied with Ge(Li) spectrometers. Coincidence spectra were taken with a Ge(Li)---Ge(Li) combination. The data do not support a recent report of several new gamma rays in the decay of ⁷⁵Se. Gamma-gamma angular correlation experiments were performed with a NaI(Tl)---Ge(Li) combination. The value obtained for δ(280 keV) is in excellent agreement with one recently reported value but in poor agreement with another. The ratio P_K/P_tot for the electron capture branch to the 401 keV level of ⁷⁵As has been determined, and the result agrees with previous experimental determinations.     

Cross sections for several (n, 2n) reactions at 14 Mev

Precision measurements of the cross sections of the (n, 2n) reactions to produce ^44mSc, ⁸⁸Y, ⁸⁹Zr, ⁹²Nb, ¹⁵⁰Eu(35y), ¹⁶⁸Tm, ^174m+gLu and ¹⁹⁶Au were made for a range of neutron energies from 13.7 to 15.0 MeV. The samples were irradiated at various positions on the surface of a 20 cm radius sphere centered at the ²H–³H neutron source. This allowed a range of neutron energies to be obtained with good energy resolution. The ²⁷Al(n, )²⁴Na reaction was used to monitor the neutron fluence in the target samples. Particular attention was given to the accurate measurement of the (n, 2n) products, using calibrated Ge(Li) and NaI(Tl) detectors. An uncertainty of about ±5% is assigned to the results, except those for ¹⁵⁰Eu and ¹⁷⁴Lu, which have an additional uncertainty in their decay schemes.     

The decay of 1.2 min Ag and 5.3 h Ag

The decay schemes of 1.2 min and 5.3 h ¹¹³Ag have been studied using Ge(Li) and NaI(Tl) detectors and a 4096-channel multiparameter pulse-height analyser system. The decay of 5.3 h ¹¹³Ag was found to involve 15 γ-rays and to produce 10 excited states in ¹¹³Cd at energies of 264.7, 298.0, 315.6, 583.9, 604.6, 681.1, 883.6, 936.9, 989.0 and 1195.2 keV. The italicized energies refer to negative parity states, through which 1.3% of the decays go to yield the isomer at 264.7 keV. The 604.6 keV level is thought to be a case|9/2⁻ level similar for those found in several odd-mass Te and Xe isotopes. The 1.2 min ^113mAg decay was found to populate several of the same levels in Cd and two additional levels at 452 and 689 keV. The 1.2 min ¹¹³Ag is the upper isomer with high spin, probably .     

Rotational excitations in residual nuclei produced by stopped negative pions on targets of Ho, Lu, Lu, Hf, and Ta

Reactions produced by stopped negative pions on targets of ¹⁶⁵Ho, ¹⁷⁵Lu, ¹⁷⁶Lu, ¹⁷⁹Hf, and ¹⁸¹Ta are investigated by measuring photons coincident with the stopped pions. These photons were detected with an 80 cm³ Ge(Li) detector and identified as pionic X-rays or rotational γ-rays from the residual nuclei. Pion capture is found to result in the excitation of high-spin states. Yields for the residual nuclei are inferred from the observed γ-transitions and compared to calculations based on the exciton model for pre-equilibrium emission followed by particle evaporation. Preliminary results of a pion stop, γn coincidence experiment are presented and compared to the calculations.     

Isomeric E1 transitions with ΔK = 0 INLu

An experimental arrangement for ns lifetime measurements in nuclear reactions is briefly described. The half-life of the level at 208.1 keV in ¹⁷¹Lu has been determined in the reaction ¹⁶⁹Tm(, 2n) ¹⁷¹Lu as . Delayed and populating γ-ray spectra have been measured, applying the method of delayed γ-γ coincidences. In the radioactive decay of ¹⁷³Hf, the lifetime of the level at 425.1 keV in ¹⁷³Lu has been measured as . Comparisons with Weisskopf and Nilsson estimates have been performed taking into account pairing correlations. A modified Nilsson Hamiltonian has been used. The dependence of El transition probabilities between the states and on the difference of the initial- and final-state deformations is studied. Qualitative agreement with semi-microscopic calculations of equilibrium deformations is found. Lifetimes of the states are estimated.     

Pb decay and M4 transition probabilities in neutron-deficient lead isotopes

The decay of 6.1 sec ^203mPb has been examined with a high-resolution Ge(Li) spectrometer, and a 5.1 keV M2 transition was found to compete with the 825.2 keV M4 isometric transition. The M4 transition probability, thus corrected, is now found to be consistent with those of the other M4 transitions in the lead region.     

全剥离离子94mRu44+的衰变研究

在兰州重离子加速器冷却储存环（HIRFL-CSR）上,用等时性质量谱仪首次研究了百微秒量级全剥离离子94mRu44+的衰变。94mRu44+由初级束流112Sn轰击Be靶产生,经过放射性束流线RIBLL2的筛选后注入到等时性设置的实验环CSRe中,并利用安装在实验环中的飞行时间探测器测量离子在CSRe中的循环周期。94mRu44+退激引起的质量改变会带来其循环周期的变化,由此直接观测到了94mRu44+退激到基态的过程。确定了本次实验中衰变事例探测的灵敏区间,并讨论了衰变发生时刻的测量精度。同时,测量了短寿命核素94mRu44+的质量,其半衰期约为100 μs,这是目前储存环质量谱仪测量的最短寿命核素的质量。The decay of the fully stripped ion 94mRu44+ in the order of one hundred microseconds has been studied for the first time by using the Isochronous Mass Spectrometry (IMS) at the HIRFL-CSR facility in Lanzhou. 94mRu44+ was produced via projectile fragmentation of a 112Sn primary beam bombarding on a 9Be production target. After the in-flight separation with RIBLL2, the ions were injected into the experimental ring (CSRe) and then stored there. The revolution times of the stored ions were measured by a Time-of-Flight (TOF) detector. Due to the mass change of a 94mRu44+ ion caused by its de-excitation to the ground state, hence the revolution time change, the decay process of 94mRu44+ could be directly observed in the CSRe. The sensitive window for detection of the decay events and the measurement precision of the decay time have been determined in this work. At the same time, we measured the mass of short-lived 94mRu44+ with the half-life about one hundred microseconds, which is the shortest among nuclides that have been studied by using storage-ring mass-spectrometry.     

New isomeric states in Fr and At

Alpha spectroscopic data from the decay chain ²¹⁸Fr → ²¹⁴At → ²¹⁰Bi have been obtained. Previously unobserved isomeric states were found in both ²¹⁸Fr and ²¹⁴At. The half-life of the ground state of ²¹⁸Fr was measured to be 1.3^+0.5 _−0.4 ms. The half-life of the new isomeric state in ²¹⁸Fr was determined to be 22.0±0.5 ms and its decay was found to be very complex with no fewer than 20 -groups varying in energy between 6837 keV and 7952 keV. Two long-lived states in ²¹⁴At with half-lives of 558±10 ns and 760±15 ns, respectively, were found to be strongly populated in the decay of ^218mFr. These two states are proposed to be a 1⁻ ground state and a 9⁻ isomeric state arising from the coupling between the unpaired h_9/2 proton and g_9/2 neutron.     

Spin-spin effect in the Ho total neutron cross section at energies of 0.4 and 1.0 MeV

Measurements of the spin-spin effect, σ_ss in the total cross section for polarized neutrons on polarized ¹⁶⁵Ho are reported at neutron energies of 0.4 and 1.0 MeV. The absence of an observable effect at 1.0 MeV is in contradiction with a recently reported experimental result. The results of an improved theoretical calculation of σ_ss for neutron energies below 8 MeV are presented and used with the new experimental data to obtain the new limit V_ss < 300 keV for the strength of the spin-spin potential.     

The decay scheme of Ag

The γ-radiations following the decay of ¹¹²Ag have been studied with Ge(Li) detectors. The ¹¹²Ag half-life has been measured as 3.16±0.02 h; twenty gamma radiations ranging in energy from 606.7 keV to 2829.6 keV have been observed.

Gamma-gamma coincidence measurements have been performed with Ge(Li) and NaI(Tl) detectors. A decay scheme consistent with the present data is proposed.     

The electron capture decay of 195Au

The decay of ¹⁹⁵Au has been investigated by means of a 4π internal source scintillation spectrometer and a Ge(Li) detector. Electron capture branching ratios and several L/K and M+…/L capture ratios have been measured. The atomic electron capture transition energy and the cross-over decay probability of the 130 keV state have been calculated.     

时间相关穆斯堡尔谱与GaAs的119mTe离子注入

本文提出并实现了一种新的穆斯堡尔谱——时间相关穆斯堡尔谱。这是利用两步衰变^119mTe→¹¹⁹Sb→¹¹⁹Sn而获得的。测量了110keV ^119mTe加10¹⁵稳定Te/cm²注入并经600℃退火的样品在不同测量时间内的穆斯堡尔谱,分析了各谱线随ξ的变化。这里ξ是我们定义的参量,它等于Φ_Te/Φ_总,由退火时刻t_{a关键词：}     

The K-, L- and M-Auger and L-Coster-Kronig spectra of platinum

The K-, L- and M-Auger and L-Coster-Kronig spectra of platinum in the electron capture decay of ¹⁹⁵Au was measured by means of the Vanderbilt iron-free, double-focussing spectrometer. The energies and relative intensities of 55 peaks were measured in the L-Auger spectrum in the energy range of 5 to 12 keV. The intensities are compared to those calculated theoretically for silver by Asaad. The total L-Coster-Kronig plus M-Auger intensity (0 to 3.25 keV) was measured relative to the L-Auger intensity. The measured relative intensities of the KLL Auger lines are compared to the theoretical and experimental results of others. The measured KLL energies agree with those calculated semi-theoretically by Hörnfeldt and by Listengarten. A value of KLX/KLL = 0.548±0.044 was measured. A measurement of the KL₃L₃(³P₀)/KL₃L₃(³P₀+³P₂) ratio, the first reported in this Z-region, gave a value of 0.095±0.024.     

The decay of Sc and V

The decays of ⁴⁸Sc and ⁴⁸V have been studied with Ge(Li) diodes, scintillation spectrometers and a double focussing beta-ray spectrometer. The 3507 keV level, from which originates the quadruple cascade (9.4±0.5)% in the ⁴⁸Sc decay, is also de-excited by a 1212 keV cross-over transition to the 2295 keV (4⁺) level and supports the assumption, that the 3507 keV level has a spin 6⁺. The first member of the reported triple cascade in the ⁴⁸V decay is shown to be a doublet of 928.9±0.7 (1.2±0.2)% and 944.3±0.5 keV (8.0±0.5)% gamma rays, both followed by the 1311.4–983.3 keV cascade. Evidence was found, that the 2421 keV (2⁺) level is excited by weak gamma rays from high-energy levels. The K/β⁺ ration in the ⁴⁸V decay is 0.69±0.05 The Q-values of ⁴⁸Sc and ⁴⁸V are calculated to be 3986±7 keV and if 4015±4 keV, respectively. The energy of the gamma ray of ⁴⁷Sc, which is present as an impurity, is 159.2±0.5 keV.     

Nuclear spins of neutron-deficient thulium isotopes

Cyclotron-produced thulium isotopes have been investigated using the atomic-beam magnetic resonance method. The spin measurements have given the following results: ¹⁵⁹Tm (9 min) , ¹⁶⁰Tm (9 min) I = 1, ¹⁶¹Tm (37 min) , ¹⁶²Tm (21.5 min) I = 1, ¹⁶⁴Tm (2 min) I = 1, ^164m Tm (5 min) I = 6 and ¹⁶⁸Tm (87 d) I = 3. An interpretation based on the Nilsson diagram for odd protons clearly indicates a systematic variation in the nuclear deformation.     

Messung des Elektroneneinfangs am Kern176m Lu

The electron capture of^176m Lu to the ground state and to the first excited state of¹⁷⁶Yb has been observed by measuring the YbK x-rays and the 82,2 keV gamma-rays from the gamma decay of the first excited state in¹⁷⁶Yb. With the data of the 88,36 keV gammarays following the beta decay of^176m Lu to the first excited state of¹⁷⁶Hf the electron capture/beta decay ratio of^176m Lu was found to be (0,95±0,16)·10^?4. The electron capture branching ratio to the ground state and to the first excited state of¹⁷⁶Yb was found to be 40/60±30%. By analyzing the 88,36keV gamma-rays and the HfKx-rays the halflife of^176m Lu was evaluated to be 3,66±0,04 h. The value for theK-conversion coefficient of the 88,36keV transition was determined from the x-ray/gamma-ray ratio to be 1,19±0,09.     

Low-intensity transitions in the decay of Rb

The γ-rays following the decay of ⁸⁸Rb have been studied with a 40 cm³ Ge(Li) detector with the aim of resolving discrepancies in some recent determinations of the decay scheme of this isotope. The existence of a 1799 keV γ-ray has been confirmed and three new γ-rays with energies of 1218, 1295 and 1368 keV have been found. All of these results are in good agreement with a decay scheme recently proposed by Ragaini and Knight.