Magnetic moment of the 2140.2 keV 5− state in136Ba

We have determined theg-factor of the 2140.2 keV 5^– state of¹³⁶Ba using the timeintegral perturbed angular correlation (IPAC) method at an external magnetic field of 17.0 kG;g=–0.38±0.04. The half-lives of the 2140.2 keV 5^– and 2207.1 keV 6⁺ states were redetermined to be 1.5±0.1 ns and 3.1±0.1 ns, respectively. The radioactive source of¹³⁶Cs was prepared by the¹³⁸Ba(, pn) reaction.     

The penetration parameter λ of the anomalousM1-conversion of the 482 keV transition in181Ta

Byγ- e _K ^? ande _K ^? -γ TDPAC measurements with the 133 keV–482 keV cascade of¹⁸¹Ta in a polycrystalline beryllium matrix theA ₂(e _K ^? )-coefficient of the 482 keV transition was determined as: A₂(482e _K ^? )=?0.095±0.015. The theoretical value is 6.0 times larger. A remeasurement of the E2/M1 mixing ratio of the same transition by integralγ- γ angular correlation measurements with a system of three 20 ccm Ge(Li)-detectors gave the result:δ(482)=4.96±0.25. Theα _K -coefficient was redetermined as:α _K (482)=0.0246±0.0018. From these data the penetration parameter:λ=157±11 is derived and compared with previously published values and theoretical estimates.     

Evaluation of the 1077 keV γ-ray emission probability from 6SGa decay

6SGa decays to the excited states of aSzn through the electron capture decay mode. New recommended values for the emission probability of 1077 keV γ-ray given by the ENSDF and DDEP databases all use data from absolute measurements. In 2011, JIANG Li-Yang deduced a new value for 1077 keV γ-ray emission probability by measuring the 69Ga（n,2n） 6SGa reaction cross section. The new value is about 20% lower than values obtained from previous absolute measurements and evaluations. In this paper, the discrepancies among the measurements and evaluations are analyzed carefully and the new values are re-recommended. Our recommended value for the emission probability of 1077 keV γ-ray is （2.72±0.16）%.     

Measurement of the 15N(α, γ)19F resonances at Ec.m. = 536 keV and 542 keV

The E_c.m. = 536 keV and E_c.m. = 542 keV resonances in the ¹⁵N(α, γ)¹⁹F reaction have been studied using a thick Ti¹⁵N target, determining ωγ = (9.7 ± 2.0) × 10⁻⁵ eV and ωγ < 1 × 10⁻⁵ eV for these two resonances, respectively. For the 542 keV resonance this value is substantially smaller than had been assumed in earlier model calculations, and this reduces the rate of the analog ¹⁵O(α, γ)¹⁹Ne reaction (connecting the Hot CNO cycle and the rp-process) by a factor of ≈ 3 for temperatures in the region of T₉ = 1.     

The half-life of the 1437 keV 11/2− state in97Mo

Using the (,n) reaction, the half-life of the first 11/2^– level in⁹⁷Mo has been determined as T_1/2(1437.0 keV)=2.5±0.3 ns by means of the pulsed beam method. The experimentally obtainedB(M2) value between theh _11/2 andg _7/2 configurations in⁹⁷Mo has been satisfactorily described within the quasiparticle-phonon model usingg _s ^eff =0.6g _s ^free . Similar calculations and comparisons with experminental data have been performed also for^95,99Mo as well as for⁹⁹Ru and¹⁰¹Pd.This work is partly supported by the Bulgarian National Research Foundation     

keV量级光子的线辐射源

在天体空间或实验室的等离子体中可能存在能量为若干keV量级的光子的线辐射,它们源于一种新的原子核物质结构形态(核核两体的松聚合)形成之时.对两个原子核组成的体系,采用库仑势垒与核力方势阱相组合的作用势,求解核核两体的定态薛定谔方程,得到了两体松束缚态的波函数和可能的能量本征量(核的长程库仑能的数量级)并说明了这种松束缚态的存在条件.对某些轻核,基态的结合能为若干keV.     

100 keV回旋电子束参数测量

 利用电子束轰击快响应荧光屏获得电子束横截面图像的方法,对100 keV大回旋轨道空心电子束(Cusp电子束)在横截面上的束轮廓及电荷密度分布进行了测量,计算出回旋电子束半径、螺旋角等参数,并与相同条件下的计算机数值模拟结果进行了对比和分析。测量结果表明初始磁场强度从0.003 5 T增加到0008 2 T时,电子束的拉莫半径从3.2 mm增加到3.9 mm,螺旋角从0.7增加到1.0,满足使用此电子束的回旋行波放大器的调试需求。     

Absolute efficiency calibration of high-purity germanium detector in the range 120–8500 keV

This article reports the efficiency response curve of the high-purity germanium detector over the wide energy range, covering from 120 to 8500 keV. The efficiencies were measured for different counting geometries by using point radionuclide standards (mono-energetic as well as multi-gamma emitters) supplied by IAEA and the capture gamma-ray facility installed at PINSTECH nuclear reactor PARR-1. The measured efficiencies were required to fit with a suitable fitting function for interpolation within the energy range of interest. Several fitting functions were proposed in the literature covering different energy ranges. The functions giving the best fit to experimental data are presented. The work has successfully extended the response curve beyond 1500–8500 keV, which is the region where the standard calibration radionuclides are not available. The thermal neutron capture gamma-ray facility provided the collimated neutron beam, extracted from the core of the reactor and made to react with ammonium chloride target to produce the capture gamma rays for determining the efficiencies in the extended region. It was found that the capture gamma-ray provides a satisfactory solution to extend the absolute efficiency calibration in the MeV range. It was also found that the fitting function that is linear in its parameter was highly satisfactory up to 1500 keV but proved insufficient upto 8500 keV. The exponential function giving the good fit over the range has been presented. Good agreement has been found between the experimentally measured absolute efficiencies and the predicted result.     

能量范围从20keV到34keV的锆元素K壳层电离截面

 用20~34keV能量的电子束轰击锆靶,从而测得锆元素的K壳层电离截面。这些数据是国际上首次报道。在实验中采用电子输运双群模型修正了由厚衬底产生的反射电子对计数的影响。同时用蒙特卡罗EGS4程序计算了电子在质量厚度为24.3mg/cm²的锆靶中的平均路径长度。     

Elastic scattering and the associated anomalous dispersion in the energy range 8.63⩽E⩽42.75 keV from heavy atoms

Elastic scattering cross-sections for Pt, Au and Pb were measured using nearly monoenergetic unpolarized Kα x-ray photons in the energy range 8.63⩽E⩽42.75 keV at an angle of 90°. The experimental results were compared with theoretical elastic scattering cross-sections calculated using relativistic form factors (RFFs), relativistic modified form factors (RMFs), a combination of RFFs, RMFs with angle-independent anomalous scattering factors (ASFs) and relativistic numerical calculations based on the multipole expansion of the second-order S-matrix approach. The experimental results were in reasonable agreement with the S-matrix values and values based on an RMF+ASF approach compared with an RFF+ASF approach. © 1988 John Wiley & Sons, Ltd.     

Search for the 70 keV resonance in17O(p, α)14N

A direct search for theE _R =70 keV resonance in¹⁷O(p, )¹⁴N was carried out using¹⁷O enriched Ta₂O₅ targets in combination with a 1 mA proton beam and suitable detectors of large solid angle. The observed upper limit for the resonance strength is8×10^–10 eV.Work supported in part by Deutsche Forschungsgemeinschaft (Ro429/21-2) and the Science Program SC1-0065 of the European Economic Community     

Measurement of the nuclear g-factor of the 1579 keV 3- state of 146Gd using a β-free measurement system

A target heating system which consists of an infrared lamp and quartz rods has been constructed. Using this system, the g-factor of the 1579 keV 3^- state of ¹⁴⁶Gd has been measured to be g(3^-)=+1.14± 22. As a result, the amplitude of the (ν f_{7/2} \otimes 3^-) component admixture in 13/2⁺ state of ¹⁴³Nd is evaluated to be 40± 9%. This revised version was published online in August 2006 with corrections to the Cover Date.     

Measurement of attenuation cross-sections of some fatty acids in the energy range 122–1330 keV

The mass attenuation coefficients (μ_m) have been measured for undecylic acid (C₁₁H₂₂O₂), lauric acid (C₁₂H₂₄O₂), tridecylic acid (C₁₃H₂₆O₂), myristic acid (C₁₄H₂₈O₂), pentadecylic acid (C₁₅H₃₀O₂) and palmitic acid (C₁₆H₃₂O₂) using ⁵⁷Co, ¹³³Ba, ¹³⁷Cs, ⁶⁰Co and ²²Na emitted γ radiation with energies 122, 356, 511, 662, 1170, 1275 and 1330 keV, respectively. The accurate values of the effective atomic number (Z_eff), atomic cross-section (σ_t,), electronic cross-section (σ_e) and the effective electron density (N_eff) have great significance in radiation protection and dosimetry. These quantities were obtained by utilizing experimentally measured values of mass attenuation coefficients (μ_m). A NaI(Tl) scintillation detector with 8.2% (at 662 keV) resolution was used for detecting of attenuated γ-photons. The variation in Z_eff and N_eff of fatty acids with energy is discussed. The experimental and theoretical results are in good agreement within 2% deviation.     

Calibrated binding energies of some core levels in the energy range between 1.5–4 keV

A commercial photoelectron spectrometer equipped with four interchangeable anodes (Mg, Al, Ag, Ti) has been utilized after careful calibration for accurately measuring binding energies of several deep core levels in the energy range between 1.5–4 keV.     

Evaluation of the 1077 keV γ-ray emission probability from ~(68)Ga decay

68Ga decays to the excited states of68Zn through the electron capture decay mode. New recommended values for the emission probability of 1077 keV γ-ray given by the ENSDF and DDEP databases all use data from absolute measurements. In 2011, JIANG Li-Yang deduced a new value for 1077 keV γ-ray emission probability by measuring the69Ga(n,2n)68Ga reaction cross section. The new value is about 20% lower than values obtained from previous absolute measurements and evaluations. In this paper, the discrepancies among the measurements and evaluations are analyzed carefully and the new values are re-recommended. Our recommended value for the emission probability of 1077 keV γ-ray is(2.72±0.16)%.     

Evaluation of the 1077 keV γ-ray emission probability from 68Ga decay

⁶⁸Ga decays to the excited states of ⁶⁸Zn through the electron capture decay mode. New recommended values for the emission probability of 1077 keV γ-ray given by the ENSDF and DDEP databases all use data from absolute measurements. In 2011, JIANG Li-Yang deduced a new value for 1077 keV γ-ray emission probability by measuring the ⁶⁹Ga(n,2n) ⁶⁸Ga reaction cross section. The new value is about 20% lower than values obtained from previous absolute measurements and evaluations. In this paper, the discrepancies among the measurements and evaluations are analyzed carefully and the new values are re-recommended. Our recommended value for the emission probability of 1077 keV γ-ray is (2.72± 0.16)%.