ON THE γ-RAY SPECTRUM OF Ra(B + C)

1952 ◽  
Vol 30 (5) ◽  
pp. 442-449 ◽  
Author(s):  
G. N. Whyte
Keyword(s):  
Recent Information ◽  
Γ Rays ◽  
Γ Ray ◽  
Good Agreement

Measurements of the transmission of Ra(B + C) γ rays through lead between 0 and 26 cm. are described and compared with the transmissions predicted on the basis of a modified version of the γ-ray spectrum of Ellis and Aston and on the basis of the spectrum of Latyshev et al. Ellis and Aston's spectrum gives the better agreement. Both the relative and absolute values of the γ-ray intensities given by Ellis and Aston are revised in the light of more recent information. This revised spectrum leads to a predicted value of 0.84 roentgens per hour at a meter for the γ-ray output of a gram of radium and its equilibrium products in 0.5 mm. of platinum, in good agreement with experiment.

Decay of 143Eu

1974 ◽  
Vol 52 (10) ◽  
pp. 847-853 ◽  
Author(s):  
G. Kennedy ◽  
S. C. Gujrathi ◽  
P. F. Hinrichsen
Keyword(s):  
Ground State ◽  
Coupling Model ◽  
Intermediate Coupling ◽  
Ground State Spin ◽  
Reaction Data ◽  
Intermediate Coupling Model ◽  
Γ Rays ◽  
Γ Ray ◽  
State Spin ◽  
Good Agreement

A high resolution study of γ-ray transitions in 143Sm following the β+ decay of 143Eu has been made using Ge(Li) detectors. Fifty-seven γ rays are assigned to the decay of 143Eu, and the ground state spin of 143Eu is established as 5/2+. Spin and parity assignments are made on the basis of γ-ray branching, deduced log ft values, and by comparison with previous (p,d) reaction data. Good agreement between experiment and predictions of the intermediate coupling model suggests that this model adequately accounts for the low lying levels of 143Sm.

A HIGH RESOLUTION FLAT CRYSTAL SPECTROMETER FOR NEUTRON CAPTURE γ-RAY STUDIES

1959 ◽  
Vol 37 (2) ◽  
pp. 203-231 ◽  
Author(s):  
J. W. Knowles
Keyword(s):  
Single Crystal ◽  
Neutron Capture ◽  
Counting Efficiency ◽  
Double Crystal ◽  
Γ Rays ◽  
Γ Ray ◽  
Antiparallel Position ◽  
Crystal Arrangement ◽  
Good Agreement ◽  
Soller Slit

A flat crystal diffraction spectrometer, constructed for the measurement of γ-rays resulting from neutron capture, is discussed both experimentally and theoretically. The spectrometer is used either as a single crystal or a double crystal instrument. In the single crystal arrangement a Laue diffracted γ-ray beam from a broad source proceeds through a Soller slit which gives it a 45-second angular divergence, to a sodium iodide scintillation detector. The energy is determined by the angle between the Soller slit and the crystal. The resolution is determined by the Soller slit, and is 4% at 1 Mev when diffracting from the (440) planes of a single germanium crystal. In the two-crystal configuration a γ-ray which is Laue diffracted from the first crystal is further diffracted from a second crystal set in the antiparallel position. The angle between the reflecting planes of the two crystals determines the γ-ray energy. The Soller slit serves only as shielding for the detector in this arrangement. The resolution depends upon the mosaics and thicknesses of the crystals; it is 0.4% at 1 Mev for diffraction from the (211) planes of two calcite crystals, each 23 mm thick and of 1.7- and 0.9-second mosaics respectively. The range of measurement extends from 80 kev to greater than 5 Mev. Where other values of γ-ray energies exist, agreement to within the expected precision, ± 0.2% is obtained. The counting efficiency as a function of energy depends on the integrated reflectivities of the crystals which may be determined at the time of a γ-ray measurement by means of the double crystal arrangement. The integrated reflectivity as a function of energy has been calculated for a number of crystals of known mosaic and throughout the range of measurement, from 0.2 to 5 Mev, good agreement is obtained.

The total energy of the γ-radiation emitted from the active deposit of actinium

1938 ◽  
Vol 34 (3) ◽  
pp. 429-434 ◽  
Author(s):  
E. Kara-Michailova
Keyword(s):  
Fine Structure ◽  
Absorption Coefficient ◽  
Total Energy ◽  
Excellent Agreement ◽  
Experimental Error ◽  
Γ Radiation ◽  
Γ Rays ◽  
Γ Ray ◽  
Good Agreement ◽  
Α Particles

The disintegrations by which Ac B passes into the inactive AcPb are accompanied by a γ-radiation very weak compared with the intense γ-emission in the case of Ra or Th-active deposit. The analysis of the secondary β-ray spectrum of actinium-active deposit has revealed the existence of at least five γ-rays (1) (see Table I), of which the ray with energy 0·349 × 106 e.V. definitely belongs to the disintegration Ac C—C″ and is associated with the fine-structure of α-particles of Ac C. According to the measurements of Surugue the two rays of 0·4038 × 106 and 0·4257 × 106 e.V. energy are to be attributed to the disintegration AcB—C, whereas the origin of the 0·829 × 106 e.V. ray is less definite. The fit with experiments is best if this ray is assumed to be emitted from Ac B—C; but it may also (within experimental error) be attributed to the disintegration Ac C″—Pb. Experiments on the absorption coefficient of the γ-radiation of RaAc and its disintegration products prove that the 0·829 × 106 e.V. ray is the hardest γ-ray emitted by the active deposit of actinium(2). The value for the absorption coefficient between 4·6 and 10·6 cm. of lead was found to be μ/ρ = 0·76, in good agreement with the value found in previous experiments at smaller absorptions in aluminium (3). There is, on the whole, excellent agreement concerning the energies of the γ-components as measured according to different methods by different observers.

THE MEASUREMENT OF ENERGIES AND INTENSITIES OF γ-RAYS WITH A PAIR SPECTROMETER

1953 ◽  
Vol 31 (4) ◽  
pp. 537-576 ◽  
Author(s):  
B. B. Kinsey ◽  
G. A. Bartholomew
Keyword(s):  
Magnetic Field ◽  
Good Method ◽  
Counting Efficiency ◽  
Coincidence Spectrum ◽  
Slit Width ◽  
Experimental Point ◽  
Γ Rays ◽  
Γ Ray ◽  
The Magnetic Field ◽  
Good Agreement

The performance of a pair spectrometer of the Walker and McDaniel type is discussed from both a theoretical and an experimental point of view. It is shown that the energy of the γ-ray may be measured to a first approximation by the product of the distance between the inner edges of the slits which define the coincidence counters and the highest value of the magnetic field at which coincidences are found. A more accurate value of the energy of the γ-ray may be obtained by adding a small correction, called the "toe" correction, to the result so obtained. The magnitude of this correction is dependent on the γ-ray energy and on the width of the slits and is obtained from calculations of the shape of the coincidence peak based on the Bethe–Heitler formula. The correction depends very little on the length of the slits or on the thickness of the radiator. The relation between the calculated correction and the slit width has been examined experimentally. It is shown that the ultimate accuracy in energy measurement depends on the homogeneity of the magnetic field and on the error involved in the calculated toe correction. The latter error can be minimized by using very narrow slits and may be eliminated by plotting the value of magnetic field at the upper limit of the coincidence spectrum against the slit width and extrapolating the curve so obtained to zero slit width. The uncertainty in the magnetic field of the present instrument introduces a possible systematic error of about 0.05%. Measured values of the energies of a number of neutron capture γ-rays are compared with the values derived from the energy balance in (d, p) reactions. The results are in good agreement (within 0.1%).The relative counting efficiency as a function of energy is calculated theoretically and found to be in good agreement with experiment from 2.75 to 7.4 Mev. Above 7.4 Mev. no good method of checking the theoretical efficiency has been found. The absolute value of the counting efficiency at 2.75 and 7.38 Mev. has been measured by an ionization chamber method and is found to be in rough agreement with theoretical estimates.

Study of the 1459-keV level in 19F by the 19F(p,p′γ)19F reaction

1970 ◽  
Vol 48 (7) ◽  
pp. 827-833 ◽  
Author(s):  
S. T. Lam ◽  
A. E. Litherland ◽  
J. J. Simpson
Keyword(s):  
Angular Distribution ◽  
Single Crystal ◽  
Linear Polarization ◽  
Proton Energy ◽  
Branching Ratios ◽  
Mixing Ratio ◽  
Γ Ray ◽  
Good Agreement

The 1459-keV level of 19F was populated by the 19F(p,p′γ)19F reaction at a proton energy of 2.78 MeV. The E2/M1 mixing ratio for the 1459 → 110 keV transition was determined to be [Formula: see text] from a combination of the γ-ray angular distribution and linear polarization and the nuclear lifetime. The γ-ray angular distribution was measured with a coaxial Ge(Li) detector and the γ-ray linear polarization with a planar Ge(Li) detector. The corresponding E2 and M1 transition strengths for a lifetime of 0.084 ± 0.020 ps are found to be [Formula: see text] and 0.10 ± 0.03 W.u. respectively. They are in good agreement with the particle–hole calculations of Benson and Flowers. The branching ratios of the 1459-keV level agree well with those of Poletti et al. The γ-ray transitions from the 1459-keV level provide a good example for demonstrating the usefulness of a single crystal Ge(Li) polarimeter.

scholarly journals Molecular Clouds Observed by the EGRET Gamma-Ray Telescope

1997 ◽  
Vol 170 ◽  
pp. 22-24 ◽  
Author(s):  
Seth. W. Digel ◽  
Stanley D. Hunter ◽  
Reshmi Mukherjee ◽  
Eugéne J. de Geus ◽  
Isabelle A. Grenier ◽  
...  
Keyword(s):  
Molecular Mass ◽  
Molecular Clouds ◽  
Gamma Ray ◽  
Angular Resolution ◽  
Cosmic Ray ◽  
High Energy ◽  
Background Rejection ◽  
Γ Rays ◽  
Γ Ray ◽  
Production Mechanisms

EGRET, the high-energy γ-ray telescope on the Compton Gamma-Ray Observatory, has the sensitivity, angular resolution, and background rejection necessary to study diffuse γ-ray emission from the interstellar medium (ISM). High-energy γ rays produced in cosmic-ray (CR) interactions in the ISM can be used to determine the CR density and calibrate the CO line as a tracer of molecular mass. Dominant production mechanisms for γ rays of energies ∼30 MeV–30 GeV are the decay of pions produced in collisions of CR protons with ambient matter and Bremsstrahlung scattering of CR electrons.

scholarly journals CROSS-SECTIONS FOR PHOTONUCLEAR REACTIONS 93Nb(γ,n)92mNb AND 93Nb(γ,n)92tNb IN THE END-POINT BREMSSTRAHLUNG ENERGIES 36...91 MeV

2020 ◽  
pp. 148-153
Author(s):  
A.N. Vodin ◽  
O.S. Deiev ◽  
I.S. Timchenko ◽  
S.N. Olejnik ◽  
A.S. Kachan ◽  
...  
Keyword(s):  
Energy Range ◽  
Cross Sections ◽  
Maximum Energy ◽  
Reaction Cross ◽  
Bremsstrahlung Spectrum ◽  
Photonuclear Reactions ◽  
End Point ◽  
Γ Ray ◽  
First Time ◽  
Good Agreement

The flux-weighted averaged over the energy range of bremsstrahlung spectrum from reaction threshold up to the maximum energy of γ-ray cross-sections <σ(E)> of the 93Nb(γ,n)92mNb and 93Nb(γ,n)92tNb photonuclear reactions were determined by the gamma-activation method within the end-point bremsstrahlung energies Еmax = 36…91 MeV. Activation of 93Nb targets has been done by a bremsstrahlung flux using an electron beam at the linear accelerator LUE-40 at RDC "Accelerator" NSC KIPT. The γ-ray spectra of irradiated targets were registered using the HPGe detector with an energy resolution of 1.8 keV for the 1332 keV line 60Co. To control the bremsstrahlung flux we used natMo witness-targets and a reaction cross-section of 100Mo(γ,n)99Mo. Obtained experimental cross-sections <σ(E)> of the studied reactions are in good agreement with the theoretical values calculated within TALYS 1.9 code and the results of other authors. The averaged cross-sections <σ(E)> of the 93Nb(γ,n)92mNb and 93Nb(γ,n)92tNb reactions in the energy range 35...45 MeV and > 70 MeV were obtained for the first time.

scholarly journals High Spin States in 193Hg

2020 ◽  
Vol 4 ◽  
pp. 170
Author(s):  
N. Fotiades ◽  
Et al.
Keyword(s):  
Excited States ◽  
High Spin ◽  
Normal Level ◽  
Beam Energy ◽  
Spin Structure ◽  
Spin States ◽  
Tandem Accelerator ◽  
High Spin States ◽  
Γ Rays ◽  
Γ Ray

The high-spin structure of 193Hg was investigated by in-beam γ-ray spectro­scopic techniques. The tandem accelerator at Daresbury Laboratory, U. K., was used to populate excited states of 193Hg through the reaction 150Nd(48Ca,5n)193Hg at a beam energy of 213 MeV and the EUROGAM detector array was used to de­ tect the γ-rays emitted by the deexciting nuclei. The normal level scheme has been further extended and a new band has been observed. In addition two new ΔI=1 structures of competing dipole and quadrupole transitions were found which will be discussed in detail.

ABSOLUTE STANDARDIZATION OF RADIOACTIVE NEUTRON SOURCES: II. THE USE OF THE F19(α, n)Na22 REACTION

1959 ◽  
Vol 37 (5) ◽  
pp. 550-556 ◽  
Author(s):  
K. W. Geiger
Keyword(s):  
Nuclear Reactions ◽  
Emission Rate ◽  
Neutron Emission ◽  
National Research Council ◽  
Neutron Output ◽  
Neutron Sources ◽  
Neutron Thermalization ◽  
Γ Rays ◽  
Absolute Standardization ◽  
Good Agreement

Fluorine has only one stable isotope, F19. If neutrons are produced by the F19(α, n)Na22 reaction the neutron output can be calculated from the yield of the resulting radioactive Na22. The growth of Na22 (half-life, 2.58 years) has been measured in a neutron source consisting originally of 1.6 curies Po210 mixed with CaF2 powder. Since Na22 is a positron emitter, discrimination against γ-rays from Po210 and from nuclear reactions could be achieved by detecting the two positron annihilation quanta in coincidence. The Na22 growth has been followed over 20 months and is in agreement with the theoretical growth curve. Comparison with a calibrated Na22 source yielded a neutron emission rate of (10.70 ± 0.25) × 104 sec−1. This resulted in a neutron emission rate of (3.16 ± 0.10) × 106 sec−1 for the Ra-α-Be source of the National Research Council, in good agreement with (3.22 ± 0.05) × 106 sec−1 obtained by a neutron thermalization method.

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