Γ-ray Intensities Research Articles

Discovery of the Shape Coexisting0+State inMg32by a Two Neutron Transfer Reaction

The "island of inversion" nucleus 32 Mg has been studied by a (t, p) two neutron transfer reaction in inverse kinematics at REX-ISOLDE. The shape coexistent excited 0+ state in 32 Mg has been identified by the characteristic angular distribution of the protons of the Δ L=0 transfer. The excitation energy of 1058 keV is much lower than predicted by any theoretical model. The low γ-ray intensity observed for the decay of this 0+ state indicates a lifetime of more than 10 ns. Deduced spectroscopic amplitudes are compared with occupation numbers from shell-model calculations.

Alpha-particle emission probabilities in the decay of 240Pu

Sources of enriched (240)Pu were prepared by vacuum evaporation on quartz substrates. High-resolution alpha-particle spectrometry of (240)Pu was performed with high statistical accuracy using silicon detectors and with low statistical accuracy using a bolometer. The alpha-particle emission probabilities of six transitions were derived from the spectra and compared with literature values. Additionally, some alpha-particle emission probabilities were derived from gamma-ray intensity measurements with a high-purity germanium detector. The alpha-particle emission probabilities of the three main transitions at 5168.1, 5123.6 and 5021.2 keV were derived from seven aggregate spectra analysed with five different fit functions and the results were compatible with evaluated data. Two additional weak peaks at 4863.5 and 4492.0 keV were fitted separately, using the exponential of a polynomial function to represent the underlying tailing of the larger peaks. The peak at 4655 keV could not be detected by alpha-particle spectrometry, while gamma-ray spectrometry confirms that its intensity is much lower than expected from literature.

Evaluation of 235U decay data

Evaluation of the complete decay scheme and data for 235U including new measurements are presented in this report; literature data available up to June 2008 are included. The half-life is determined to be (7.04±0.01)×108yr. All known measured γ-ray absolute intensities have been examined; the γ-ray emission probability of the reference γ-ray line of 185.72keV is recommended to be 57.0±0.3%. The calculated internal conversion coefficients and their uncertainties have been used to obtain the complete decay intensity balance. The other decay characteristics are calculated using the ENSDF analysis program. Finally the new decay scheme for 235U is presented.

Determination of the neutron flux and γ radiation in the core of operating and shut-down reactors using quartz glasses and element monitors

The neutron fluxes and the intensity of γ radiation are measured in 26 channels of a WR-SM reactor and its thermal column. The fast neutron fluxes in the channels are determined using Ni, Fe, Co, Au, and Mn element monitors with different threshold energies, together with a theoretical calculation using the MCNP-4C program. The energy distribution of the neutron flux inside the fuel assembly is obtained for selected channels around the core. The flux of neutrons with energies >1 MeV is in the range (0.5-43).10 12 cm -2 sec -1 , depending on the location of the channel. A linear correlation is discovered between the induced optical absorption at the 215 nm line (E' center) of SiO 2 -BaO glass and the fast neutron flux in the channels. The γ-ray intensity in the thermal channel is estimated for the reactor during operation (∼38.4 Gy/sec) and 24 hours after it is shut down (∼24. 7 Gy/sec ) using the E' centers induced in pure quartz glasses. The observed difference in the efficiency with which oxygen defects are formed during dry and wet irradiation of glass owing to the radiolysis of water must be taken into account when developing radiation technology and during the burial of radioactive waste.

Precise Intensity Measurements in the 14N(n, γ)15N Reaction as a γ-Ray Intensity Standard up to 11MeV

The main γ-ray intensities in the 14N(n, γ)15N reaction were determined at an accuracy of 0.3–1.0% based on the intensity balance principle. Measurements were performed at the supermirror neutron guide tube at the Kyoto University reactor (KUR). A liquid nitrogen target and a deuterated melamine (C3D6N6) one were used. We prepared a full-energy-peak efficiency curve by combining the measured and calculated efficiency curves. The previous values widely used as intensity standards agreed with the present results within 4–5% in the 2–11 MeV region, but the ratio to the present values showed a monotonic decrease with the increase in _-ray energy. The results reported by Belgya in 2006 agreed with the present one within 2–3% in the 2–8MeV region; nevertheless, the ratio showed a small oscillation versusγ-ray energy.

Radio waves and γ-ray emission from astrophysical sources

A mechanism of X- and γ-ray emission by relativistic electrons at interaction with astrophysical objects (maser clouds) is considered and the contribution of this mechanism to the formation of a continuous spectrum and its correlation with radio-wave radiation are investigated. The radiation yield upon deexcitation of a quantum system by an electron exceeds that of “conventional” (i.e., without a change in the quantum-system state) bremsstrahlung at small nuclear charges (Z < 10) and may be about 8% of the total γ-ray intensity. It is shown that in the direction in which the γ-ray intensity increases, one should observe radio waves corresponding to a particular maser source.

Investigation on the fuzzy recognition mechanism for γ-ray fingerprints of nuclear materials

Within the scope of the two_dimensional space with the energy and intensity of γ-ray as coordinates, we brought forward the concept of the two_dimensional fuzzy set about spectra, and established the membership function. We also introduced the fundamental principles and method for identifying the γ-ray fingerprints by fuzzy recognition technique. By regularizing the spectra, we succeeded in identifying the types and individuals of nuclear materials. Further more, we introduced the multiplying factor, and thus obtained high degree of confidence in identifying the spectra. We identified the simulation materials as radiation sources with the method, and studied the influence of the detecting distance and the detecting system fluctuation on the membership degree. The results show that the method has strong capabilities of identifying the types and the individuals of radiation sources, and can be applied to the nuclear materials safeguard.

Precise Intensity Measurements in the 14N(n, γ)15N Reaction as a γ-Ray Intensity Standard up to 11 MeV

Precise Intensity Measurements in the 14N(n, γ)15N Reaction as a γ-Ray Intensity Standard up to 11 MeV

Spectral fit of Cygnus X-1 in high energy— a self-consistent study

We fit the spectra of Cyg X-1 using two component advective flows with Keplerian accretion disks on the equatorial plane surrounded by sub-Keplerian disks when standing shocks are present. The soft photons generated by the bremsstrahlung and synchrotron processes in the sub-Keplerian flow, as well as the multi-colour black body emission from the Keplerian disk are Comptonized by the thermal and non-thermal electrons. By varying Keplerian and sub-Keplerian rates we are able to reproduce the observed soft and hard states as far as X-ray region is concerned and ‘low γ-ray intensity’ and ‘high γ-ray intensity’ states as far as the soft γ-ray region is concerned. We also find two pivotal points where the spectra intersect as is observed in Cyg X-1.

Doppler analysis of hydrogen motion on Pt(1 1 1)–Sn surface alloys using the 1H(15N,αγ)12C nuclear reaction

Hydrogen adsorbed on the Pt(111)–Sn surface alloys was investigated by nuclear reaction analysis (NRA) using 1H(15N,αγ)12C. The γ-ray intensity profile as a function of the incident ion energy is analyzed on the basis of the Doppler broadening. From the widths of the resonance profiles, the zero-point vibrational energies in the vertical and in-plane directions are estimated to be 78.2±3.7 and 53.6±5.8meV on Pt(111)2×2–Sn, respectively, and 72.5±3.7 and 58.5±6.7meV on Pt(111)√3×√3–Sn, respectively. The adsorption state and vibrational property of H on the surface alloys are discussed.

Nuclear Data Sheets for A = 221

The 1990 Nuclear Data Sheets for A = 221 mass chain (1990Ak05) have been updated on the basis of the experimental results from various reaction and decay studies leading to nuclides in the A = 221 (Z = 85 to 92) since July 1990 (cutoff date of the last evaluation). The results obtained from various theoretical studies are given as comments. The updated level schemes and decay schemes, and experimental decay and reaction data on which they are based, are summarized and presented for all nuclides with mass number A = 221. The adopted values of level energies, level spins and parities are given, and γ-ray energies, γ-ray intensities, as well as other nuclear properties are presented. The references, Jπ arguments, and necessary comments are given in the text. New measurements have been reported in Rn,Fr,Ra, and Ac and one new nuclide ( 221U) has been given. All Q values have been adopted from 2003Au03.

Evaluation of 225Ac decay data

Evaluation of the complete decay scheme and data for 225Ac including new measurements are presented in this report; literature data available up to March 2006 are included. The half-life is determined to be 10.0±0.1 days. All known measured γ-ray relative intensities have been examined; the γ-ray emission probability of the reference γ-ray line of 150.04 keV is recommended to be 0.693±0.012%. The calculated internal conversion coefficients and their uncertainties have been used to obtain the complete decay intensity balance. The other decay characteristics are calculated using the ENSDF analysis program. Finally, the new decay scheme for 225Ac is presented.

Nuclear Data Sheets for A = 251

Nuclear spectroscopic information for known nuclides of mass number 251 with Z = 96 to 102 (Cm,Bk,Cf,Es, Fm,Md,No) and N = 155 to 149 have been evaluated and presented together with adopted energies and Jπ of levels in these nuclei. No excited state data are yet available for 251Cm. This evaluation supersedes previous full evaluation of A = 251 by A. Artna-Cohen (1999Ar21) with literature cutoff date of Jul 1999. Inconsistencies and discrepancies are noted. The adopted values of level energies, level spins and parities are given, and γ-ray energies, γ-ray intensities, as well as other nuclear properties are presented. The references, Jπ arguments, and necessary comments are given. Theoretical studies are given as comments. New measurements have been reported in 251No, 251Md, 251Cf and 251Es. All adopted Q values are from 2003Au03. 2004Pa31 give calculated neutron separation energy by a macroscopic-microscopic approach.

Can 29 kDa rhGM-CSF expressed by Silkworm pupae bioreactor bring into effect as active cytokine through orally administration?

In order to study the effect of human granulocyte-macrophage colony-stimulating factor (hGM-CSF) as active cytokine through orally administration, we expressed hGM-CSF within silkworm pupae bioreactor. The purified rhGM-CSF named as BmrhGM-CSF is characterized as 29 kDa glycoprotein, and its biological activity was measured both in vitro and in vivo. We found out BmrhGM-CSF could stimulate the colony formation of human bone marrow cells in a dose-dependent manner whether which were treated with or without γ-ray 24 h before. The ability of colony formation induced by BmrhGM-CSF is negatively correlated with γ-ray intensity. As soon as 15 min post oral administration with BmrhGM-CSF labeled with 125I, an approximately 20 kDa protein fragment was detected within mice blood by SDS-PAGE followed by autoradiography. In blood sample of test mice, a protein was also recognized by anti-hGM-CSF antibody using ELISA. The immunohistochemical analysis showed that BmrhGM-CSF was detected within intestinal histiocyte. This indicated it might be absorbed into blood via intestinal microvillus. Pharmacokinetics analysis after orally administered BmrhGM-CSF in animal model of leucopenia including mice, Beagle dogs and macaques showed that: (1) BmrhGM-CSF promoted the CFU-S formation in mice spleen and the synthesis of DNA in bone marrow cells of mice; (2) BmrhGM-CSF induced bone marrow karyocyta granulocyte growth significantly in both macaques and Beagle dogs compared to the negative control group. On the 9th day of orally administration, the animal WBC significantly increased in a dose-dependant manner, in which neutrophilic granulocyte was predominant. The WBC level of dogs in high dose group was about 1.5 × 10 9 cells/L more than that in the negative control. And the bone marrow smear revealed that the percents of both myloblast and progranulocyte in WBC in the hGM-CSF group were obviously higher than those in the negative control. These results proved that BmrhGM-CSF, a 29 kDa glycoprotein expressed by Silkworm pupae bioreactor, could bring into the effect as active cytokine through oral administration.

The Spectral Properties of Shocked Two-Component Accretion Flows in the Presence of Synchrotron Emission

Two-component advective flows have Keplerian accretion disks on the equatorial plane that is surrounded by sub-Keplerian transonic flows. In this Letter, we study the spectral properties of these flows when the shocks are present. The shock acceleration produces nonthermal electrons in the postshock region that in turn produce power-law synchrotron radiation. The soft photons generated by the bremsstrahlung and synchrotron processes in the sub-Keplerian flow, as well as the multicolor blackbody emission from the Keplerian disk, are Comptonized by the thermal and nonthermal electrons. By varying Keplerian and sub-Keplerian rates, we are able to reproduce the observed soft and hard states as far as the X-ray region is concerned and low γ-ray intensity and high γ-ray intensity states as far as the soft γ-ray region is concerned. We also find two pivotal points where the spectra intersect, as is observed in, e.g., Cyg X-1.

Gamma-Ray Spectral Characteristics of Thermal and Non-Thermal Emission from Three Black Holes

Cygnus X-1 and the gamma-ray transients GRO J0422+32 and GRO J1719-24 displayed similar spectral properties when they underwent transitions between the high and low gamma-ray (30 keV to few MeV) intensity states. When these sources were in the high γ-ray intensity state (γ2, for Cygnus X-1), their spectra featured two components: a Comptonized shape below 200-300keV with a soft power-law tail (photon index >3) that extended to ~1MeV or beyond.When the sources were in the low-intensity state (γ0, for Cygnus X-1), the Comptonized spectral shape below 200 keV typically vanished and the entire spectrum from 30 keV to ~1MeV can be characterized by a single power law with a relatively harder photon index ~2–2.7. Consequently the high- and low-intensity gamma-ray spectra intersect, generally in the ~400 keV – ~1MeV range, in contrast to the spectral pivoting seen previously at lower (~10 keV) energies. The presence of the power-law component in both the high- and low-intensity gamma-ray spectra strongly suggests that the non-thermal process is likely to be at work in both the high and the low-intensity situations. We have suggested a possible scenario (Ling & Wheaton, 2003), by combining the ADAF model of Esin et al. (1998) with a separate jet region that produces the non-thermal gamma-ray emission, and which explains the state transitions. Such a scenario will be discussed in the context of the observational evidence, summarized above, from the database produced by EBOP, JPL's BATSE earth occultation analysis system.

High-resolution γ-ray spectroscopy of hyperfragments produced by stopped [formula omitted] reactions

We performed an experiment to measure γ rays of hyperfragments produced by stopped K − reactions on light ( A ⩽ 12 ) targets (KEK-PS E509). We clearly observed an E2 transition ( 5 / 2 + → 1 / 2 + ) in 7 Λ Li with 10B, 11B and 12C targets and obtained the γ-ray intensity to be ( 7.5 ± 1.6 ) × 10 −4 per stopped K − for 10B target. In addition, a candidate for a new hypernuclear γ ray was observed. These results show that this method is quite suitable for the systematic study of hypernuclei.

A Gravitational Mossbauer Spectrometer Based on Long-Lived 109m Ag

Descriptions are given of the operating principle and design of a gravitational Mossbauer spectrometer based on the long-lived isomer 109mAg. The measured quantity is the 88 keV γ-ray intensity from a fairly thick silver source containing atoms of the parent nuclide 109Cd.

Nuclear Data Sheets for A = 197

The 1995 Nuclear Data Sheets for A = 197 (1995Zh27) have been updated on the basis of the experimental results from various decay and reaction studies leading to nuclides in the A = 197 mass chain since January 1995 (cutoff date of the last evaluation). The updated level schemes and decay schemes, and experimental decay and reaction data on which they are based, are summarized and presented for all nuclides with mass number A = 197. The adopted values of level energies, level spins and parities are given, and γ-ray energies, γ-ray intensities, as well as other nuclear properties are presented. The references, Jπ arguments, and necessary comments are given in the text.

Emission probability measurement of γ-ray of 105Rh

105Rh becomes a stable 105Pd after β −-decay with a half-life of 35.36 h. The energies of especially strong γ-rays emitted from 105Rh are 306.1 and 318.9 keV, and the emission probabilities are evaluated to be 5.1±0.3% and 19.1±0.6% by de Frenne et al. To improve the certainty, the γ-ray emission probabilities were determined from the disintegration rate and absolute γ-ray intensities measured using a 4πβ(ppc)-γ(HPGe) coincidence apparatus with two-dimensional data-acquisition system. The results for the 306.1 and 318.9 keV γ-rays were 4.76±0.05% and 16.99±0.17%, respectively.