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1.
We have determined the isomeric ratios in 74Se(γ, n) 73m,gSe and 82Se(γ, n) 81m,gSe photonuclear reactions of natural Selenium induced by bremsstrahlungs with end-point energies in the giant dipole resonance
region. The investigated samples were irradiated at electron accelerator Microtron MT-25 of the Flerov Laboratory of Nuclear
Reaction, Joint Institute for Nuclear Research, Dubna, Russia. The gamma spectra of the samples irradiated were measured with
spectroscopic system consisting of 8,192 channel analyzer and high-energy resolution (180 keV at gamma ray 1,332 keV of 60Co) HP(Ge) semiconductor detector Canberra. The GENIE2000 (Canberra) computer program was used for data processing. The results
were discussed and compared with those of other authors. 相似文献
2.
We have determined the isomeric ratios in 130Ba(γ, n) 129m,gBa, 132Ba(γ, n) 131m,gBa and 134Ba(γ, n) 133m,gBa photonuclear reactions of natural barium induced by bremsstrahlungs with end-point energies in the giant dipole resonance
region. The investigated samples were irradiated at electron accelerator Microtron MT-25 of the Flerov Laboratory of Nuclear
Reaction, Joint Institute for Nuclear Research, Dubna, Russia. The gamma spectra of the samples irradiated were measured with
spectroscopic system consisting of 8192 channel analyzer and high-energy resolution (180 keV at gamma ray 1332 keV of 60Co) HP(Ge) semiconductor detector Canberra. The GENIE2000 (Canberra) computer program was used for data processing. The results
were discussed and compared with those of other authors. 相似文献
3.
We have determined the isomeric ratios in 120Te(γ, n) 119m,gTe, 122Te(γ, n) 121m,gTe, 128Te(γ, n) 127m,gTe and 130Te(γ, n) 129m,gTe photonuclear reactions of natural tellurium induced by bremsstrahlungs with end-point energies in the giant dipole resonance
(GDR) region. The investigated samples were irradiated at electron accelerator Microtron MT-25 of the Flerov Laboratory of
Nuclear Reaction, Joint Institute for Nuclear Research, Dubna, Russia. The gamma spectra of the samples irradiated were measured
with spectroscopic system consisting of 8192 channel analyzer and high-energy resolution (180 keV at gamma ray 1,332 keV of
60Co) HP(Ge) semiconductor detector Canberra. The GENIE2000 (Canberra) computer program was used for data processing. The results
were discussed and compared with those of other authors. 相似文献
4.
We have determined the isomeric ratio of 85m,gSr in photonuclear reactions of natural strontium induced by bremsstrahlungs with end-point energies in the giant dipole resonance
(GDR) region as well as the isomeric ratios of 85m,gSr and 84m,gRb produced at 65 MeV bremsstrahlung. In GDR region the target was irradiated at electron accelerator Microtron MT-25 of the
Flerov Laboratory of Nuclear Reaction, Joint Institute for Nuclear Research, Dubna, Russia. The target irradiation with 65 MeV
bremsstrahlung was performed at the linear electron accelerator of the Pohang Neutron Facility, Pohang, South Korea. The gamma
spectra of the samples irradiated in both cases were measured with spectroscopic systems consisting of 8192 channel analyzer
and high-energy resolution (180 keV at gamma ray 1332 keV of 60Co) HP(Ge) semiconductor detector Canberra. The GENIE2000 (Canberra) computer program was used for data processing. The results
were discussed and compared with those of other authors. 相似文献
5.
In geochemistry, the distribution of the Rare Earth Elements (REEs) in earth crust and mantle allows to understand geochemical
cycles and origin and age of igneous rocks. In this article REEs (Ce, Dy, Eu, La, Nd, Sm, Tb, and Yb), Th and U in ores of
the North-Latium (Bracciano area, Ceriti Mt., Fate Mt., Sabatini Mt., Vulsini Mt., Acqua Rossa basin), have been investigated
for evaluating the extraction feasibility for industrial applications. 107 samples were irradiated in the rotating rack of
the TRIGA Mark II reactor of the R.C. Casaccia (ENEA) at neutron flux of 2.6 × 10 12
n × cm −2 × s −1 for 12 h together with primary and secondary standards. The gamma spectrometry measurements were performed after 8 h, 3 and
30 days of decay by means of HPGe detector (FWHM 1.75 keV at 1332.5 keV, peak/Compton ratio 55.1, relative efficiency of 22%)
connected to a multi-channel analyzer. The total REE mean content is 105 μg g −1, ranging widely between 2.23 and 410.5 μg g −1 (average coefficient of variation 112%). A similar behavior is found for Th and U: their average levels are 13.5 and 6.0 μg g −1, respectively. A quite good correlation between REEs and Th (and U) is found for Ceriti Mt. ( r
2 > 0.8) whereas for the other areas the correlation is <0.7. The results obtained evidence the low U content in the investigated
locations. 相似文献
6.
The aim of our studies is to check the possibilities of using proton activation analysis as a competitive method over other
analytical techniques applied for iodine determination. It is well known that long-term irradiation of biological samples
leads to their decomposition and formation of gaseous radiolysis products, which increase the pressure inside the sample container.
In case of using proton beam another problem with liquid samples appears. It is the production of 7Be via spallation reactions 16O(p, spall) 7Be. The Compton effect from 7Be γ-line increases the detection limits for isotopes with low-energy γ-lines. AIC-144 cyclotron at The Niewodniczański Institute
of Nuclear Physics Polish Academy of Science can accelerate protons up to energy of 60 MeV which is sufficient for (p,5n)
reaction needed to obtain 123I ( T
1/2 = 13.27 h, Eγ = 159 keV, I = 83%) from stable 127I, thus the Compton effect from 7Be was the main factor perturbing the analysis. Separation and removal of 7Be is required to improve the detection limit. The paper presents a method and an example of its application to the determination
of iodine concentration in digested fragments of human thyroids obtained during surgical treatment of patients with different
types of thyroid tumor. 相似文献
7.
The determination of gold is based on the photoexcitation reaction 197Au(γ,γ’) 197mAu with the half-life of 7.73 seconds and energy of emitted gamma-rays of 279 keV. Three 100 ml aliquots of coarsely ground
Au-ore (grains <2 mm) corresponding to ca. 150–180 g were irradiated for 20 seconds with bremsstrahlung of maximum energy
10 MeV produced by a microtron at the electron beam current of 30–40 μA, 1–10 times reactivation was applied. After 3 seconds
of decay, samples were measured for 20 seconds using scintillation or semiconductor gamma-spectrometry with the detection
limits for an ideal sample down to 0.5 μg·g −1 and 0.1–0.2 μg·g −1 of Au, respectively. Content of U and Th undergoing photo-fission increases the detection limits several times. 相似文献
8.
This work presents the experimental study of the isomeric ratio of 137mCe–137gCe produced in 138Ce(γ, n) 137m,gCe photonuclear reaction, in neutron capture reaction 136Ce(n, γ) 137m,gCe and in the two simultaneous reactions 138Ce(γ, n) 137m,gCe and 136Ce(n, γ) 137m,gCe in the mixed photon—neutron field by the activation method. The investigated samples were irradiated at the bremsstrahlung photon flux, in the epithermal and thermal-epithermal neutron beam and in the mixed photon-neutron field constructed at the electron accelerator Microtron MT-25 of the Flerov Laboratory of Nuclear Reaction, Joint Institute for Nuclear Research, Dubna, Russia. The results were analyzed, discussed and compared with those of other authors to examine the role of the channel effect in nuclear reaction and provide the nuclear data for theoretical model interpretation of nuclear reactions. 相似文献
9.
The results of experiments on the preparation of carrier-free lanthanides from some targets irradiated in the U-120 cyclotron
are presented. In the reactions 151Eu(α, n) 154m,154Tb, 151Eu(α, 2n) 153Tb, 155Gd(α, 2n) 157Dy, 169Tm(α, n) 172Lu and 169Tm(α, 2n) 171Lu, the isotopes 154m,154+153Tb, 157Dy and 172+171Lu were obtained. These were seaprated by means of ion-exchange chromatography.
Part II: see Ref. 2 相似文献
10.
The thermal neutron cross-sections and resonance integrals of the 186W ( n,γ) 187W and 98Mo ( n,γ) 99Mo reactions in the thermal and 1/ E regions, respectively, of a thermal reactor neutron spectrum have been experimentally determined by the activation method
using 197Au ( n,γ) 198Au reaction as a single comparator. The high purity natural W, Mo, and Zr foils; and Au wire diluted in aluminum, were irradiated
without Cd shield in two neutron irradiation sites, characterized with different values for the thermal-to-epithermal flux
ratios, f at the Second Egyptian Research Reactor (ETRR-2). The induced activities in the samples were measured by high-resolution
γ-ray spectrometry with a calibrated germanium detector. Thermal neutron cross-sections for 2200 m/s neutrons and resonance
integrals for the 186W ( n,γ) 187W and 98Mo ( n,γ) 99Mo reactions have been obtained relative to the reference values, σ 0 = 98.65 ± 0.09 b and I
0 = 1500 ± 28 b for the 197Au ( n,γ) 198Au reaction. The necessary correction factors for thermal neutron and resonance neutron self-shielding effects, and the epithermal
flux index (α) were taken into account in the determinations. The results obtained were: σ 0 = 38.43 ± 0.4 b and I
0 = 502 ± 65 b for 186W ( n,γ) 187W, and σ 0 = 0.137 ± 0.014 band I
0 = 6.47 ± 0.8 for 98Mo ( n,γ) 99Mo. These results are discussed and compared with previous measurements and evaluated data in literature. The traditional
method of determining thermal cross-sections and resonance integrals via neutron irradiation with and without Cd shield in
one irradiation position was avoided in this work by neutron irradiation without Cd shield in at least two different neutron
irradiation positions. This method provides alternative way for determining thermal cross-sections and resonance integrals
simultaneously. 相似文献
11.
A systematic and non-destructive technique is proposed for the determination of boron in coral samples by neutron-induced
prompt γ-ray analysis (PGA) using a thermal neutron guide beam of the JRR-3M reactor. About 50–150 mg samples in sealed FEP
film were irradiated and measured for 5000 s in the PGA system at a neutron flux of 2.4 × 10 7 n cm −2 s −1. In order to determine B content in coral skeletons, the Doppler-broadened γ-ray peak of 478 keV ( 10B) was used together with the correction of interference from the Na-peak of 472 keV. The analytical precision was ~3% for
the JCp-1 coral standard. The data ( n = 56) obtained by the present method showed a range of B content from 40.7 to 76.9 ppm which is similar to reported values.
Boron in corals showed the highest levels in Rukan-sho (Okinawa) with an average B content of 62.5 ppm, whereas corals collected
from Mizugama (Okinawa), Cebu (the Philippines) and Khang Khao (Thailand) exhibited B contents of 56.5, 53.0 and 45.7 ppm,
respectively. The uptake of boron by living corals may be influenced by seawater pH related to higher seawater B(OH) 4−. In this paper we discuss factors controlling the B levels in corals. 相似文献
12.
The induced activity of the 99Mo isotope is mostly determined via the 140.5 keV γ-line, which is the strongest gamma-ray of its daughter, 99mTc. Some recent literature, however, indicates a direct feeding of this energy level from the mother isotope as well. Considering
the importance of this line in practice as well as the large controversy and scattering in relevant nuclear data available
at present, a combined effort was made to remeasure this questionable absolute intensity. A relative method of irradiating
a Mo-target with reactor neutrons and repeatedly measuring its (n,γ) induced activity relative to the 181.1 keV and 739.5
keV gamma lines of 99Mo as internal references was used. The weighted average of different runs yielded γ( 99Mo, 140.5 keV)=(5.07±0.37)%. As a consequence, when the 140.5 keV gamma line is used, the contribution from the 99Mo mother isotope should always be taken into account, e.g. in neutron cross-section measurements and neutron activation analysis. 相似文献
13.
The nucleus 23Na has been investigated by studying the primary γ-rays emitted from 53 keV neutron capture in it using a high resolution
and high efficiency (100%) HPGe detector and NaI(T1) detector for anti-Compton. 24 primary γ-rays were placed in the 24Na, in which 3 primary γ-rays were new ones from a (n, γ) reaction, and reported for the first time. In order to obtain an
exact energy calibration within 7 MeV, 56Fe(n,γ) 57Fe reaction was used at thermal neutron energy. Intensity calibration was obtained from the 27Al(p,γ) 28Si reaction at E
p=2046 keV. The neutron binding energy of 24Na was determined to be 6959.75 keV. 相似文献
14.
The 168mLu ( T
1/2=6.7 min) (EC + β +) decay was reinvestigated by direct γ and γ-γ coincidence measurements using a continuous radiochemical separation from its 168Hf parent produced by 156Gd( 16O,4n) reaction. Energies and intensities of 171 γ-transitions assigned to 168Lu decay were accurately measured, among the 97 were found for the first time. 相似文献
15.
Astatine-211 ( T
1/2 = 7.214 h) is an α-emitter at secular equilibrium by EC with its ultra-short-lived α-emitting daughter, polonium-211g ( T
1/2 = 0.516 s), with a high Linear Energy Transfer (LET — 130 eV·nm −1) and a half-life suitable for metabolic radiotherapy; the overall α branching of the 211At/ 211gPo system is 100%. The direct production of 209Bi(α,2n) 211At/ 211gPo seems the most satisfactory method; Bi targets were irradiated at JRC-Ispra Cyclotron of European Commission, EC, using
α-energy higher than 28.61 MeV in order to produce, via 209Bi(α,3n) reaction, small amounts of the γ-emitter 210At (used as internal spike). 相似文献
16.
In situ gamma-ray measurements were taken at six locations in the Modane Underground Laboratory. Count rates for gamma radiation
within the energy range of 7–2734 keV varied from 15 to 108 γs −1. The arithmetic mean was 79 γs −1 for measurements taken without a collimator. The metamorphic rocks surrounding the Lab are characterized by low activity
concentrations of uranium and thorium equal to 12 and 10 Bq kg −1, respectively. 相似文献
17.
Photon activation analysis has been success-fully applied to the fast and non-destructive analysis of tin in cassiterite ores
based on the 159.7 keV gamma line of 123mSn produced in the 124Sn/γ, n/ 123mSn reaction. In order to improve the accuracy of analytical results, corrections for self-absorption and pile-up effects were
performed. Under typical conditions /15 μA electron beam current, 15 MeV bremsstrahlung energy, 5 min irradiation time and
10 min measurement/ the sensitivity of the analysis is 10 ppm. The proposed method can be used for routine analysis of tin
in geological samples. 相似文献
18.
Thanks to its favorable decay characteristics, 177gLu is finding several applications in nuclear medicine, especially for palliative metabolic radiotherapy of cancer and radioimunotherapy.
177gLu is produced in thermal nuclear reactor either by direct neutron capture 176Lu(n,γ) 177(m+g)Lu on either natural or enriched 176Lu target, or by reaction on enriched 176Yb target followed by negatron decay. The latter method does produce a high radionuclidic purity and high specific activity
radionuclide in no-carrier-added form, since 177Yb decays solely to the ground state 177gLu. Conversely, the first method does produce a low specific activity 177gLu in carrier-added form, 1 contaminated by the long-lived radioisotopic impurity 177mLu. The accurate determination of radionuclidic purity and half-life of 177gLu carried out by HPGe and LSCS is presented in some details. 相似文献
19.
172Lu due to its suitable ( T
1/2 = 6.7 days) and high detection sensitivity, is used as a radiotracer in different fields. 172Lu appears to be suitable as a long-lived rare-earth tracer for compound labelling and biodistribution studies. In the present
study, excitation functions via 172Yb(p,n) 172Lu, natYb(p,xn) 172Lu, 172Yb(d,2n) 172Lu and natYb(d,xn) 172Lu reactions were calculated by ALICE/91, ALICE/ASH and TALYS-1.2 codes. Deposition of natYb 2O 3 on Cu substrate was carried out via sedimentation method for the production of 172Lu. Cementation separation process and liquid–liquid extraction (LLX) of no-carrier-added (nca) radiolutetium from irradiated
ytterbium(III)oxide target hydrochloric solution was described using Na(Hg) amalgam, α-hydroxyisobutyric acid (α-HIB) and
di-(2-ethylhexyl)phosphoric acid (HDEHP). 相似文献
20.
In recent years, there has been a rapid expansion in the use of radio nuclides for therapeutic purposes. Thulium–167 is an
important radionuclide ( T
1/2 = 9.25 d) due to it could be used for tumor and bone studies in nuclear medicine. 167Tm complexed with hydroxy ethylene diamine tetra-acetic acid (HEDTA) could be used with the aim of bone imaging. 167Tm emits a prominent γ ray of 208 keV energy and low energy electrons. This study describes calculations on the excitation
functions of 165Ho(α,2 n) 167Tm, 167Er( p, n) 167Tm, natEr( d, xn) 167Tm and natEr( p, xn) 167Tm reactions by ALICE/ASH (hybrid and GDH models) and TALYS-1.0 codes. In addition, calculated data by codes were compared
to experimental data that earlier were published and TENDL-2010 database. Moreover, optimal thickness of the targets and physical
yield were obtained by SRIM (stopping and range of ions in matter) code for each reaction. According to the results, the 167Er( p, n) 167Tm and 165Ho(α,2 n) 167Tm reactions are suggested as the best method to produce 167Tm owing to minimum impurities. The TALYS-1.0 code, predict the maximum cross-section of about 382 mb at 11 MeV and 849 mb
at 26 MeV for 167Er( p, n) 167Tm and 165Ho(α,2 n) 167Tm reactions, respectively. Finally, deposition of natEr 2O 3 on Cu substrate was carried out via the sedimentation method. The 516 mg of erbium(III)oxide with 103.2 mg of ethyl cellulose
and 8 mL of acetone were used to prepare a natEr 2O 3 layer of 11.69 cm 2. 167Tm was produced via the natEr( p, n) 167Tm nuclear process at 20 μA current and 15 → 7 MeV protons beam (1 h). Yield of about 3.2 MBq 167Tm per μA h were experimentally obtained. 相似文献
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