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 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.

THE NEUTRON CAPTURE 7-RAYS FROM POTASSIUM

1953 ◽  
Vol 31 (6) ◽  
pp. 927-931 ◽  
Author(s):  
G. A. Bartholomew ◽  
B. B. Kinsey
Keyword(s):  
Excited State ◽  
Potassium Carbonate ◽  
Ground State ◽  
Neutron Capture ◽  
State Transition ◽  
Ground State Transition ◽  
Γ Rays ◽  
Γ Ray

The capture γ-rays from potassium have been re-examined with greater resolution than was used in previous experiments. The upper end of the spectrum has been carefully studied both with a sample of natural potassium carbonate and with another in which the potassium was enriched in K40. From a comparison of the spectra two γ-rays with energies of 9.39 ± 0.06 and 8.45 ± 0.02 Mev. are assigned to capture by that isotope. The strong γ-ray at 7.757 ± 0.008 Mev. previously ascribed to the ground state transition in K40 is now found to represent a transition to a low-lying excited state in that nucleus.

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.

Thermal neutron capture γ-ray spectrum of molybdenum and ruthenium

1991 ◽  
Vol 69 (6) ◽  
pp. 658-664 ◽  
Author(s):  
M. A. Islam ◽  
T. J. Kennett ◽  
W. V. Prestwich
Keyword(s):  
Thermal Neutron ◽  
Neutron Capture ◽  
Nuclear Reactor ◽  
Thermal Neutron Capture ◽  
Global Average ◽  
Transition Level ◽  
Γ Rays ◽  
Γ Ray ◽  
Strength Functions ◽  
Mcmaster University

The thermal neutron capture γ rays from natural molybdenum and ruthenium have been studied using a pair spectrometer and the tangential facility at the McMaster University Nuclear Reactor. Precise transition, level, and neutron separation energies of different isotopes are inferred. The separation energies are: Sn(93Mo) = 8069.76 ± 0.09, Sn(95Mo) = 7369.10 ± 0.10, Sn(96Mo) = 9154.31 ± 0.05, Sn(97Mo) = 6821.15 ± 0.25, Sn(98Mo) = 8642.55 ± 0.07, Sn(99Mo) = 5925.42 ± 0.15, Sn(100Ru) = 9673.48 ± 0.05, and Sn(102Ru) = 9219.64 ± 0.05 keV. The M1 strength functions of 100Ru,102Ru, 96Mo, and 98Mo are (34 ± 15) × 10−9, (82 ± 41) × 10−9, (22 ± 7) × 10−9, and (25 ± 8) × 10−9 MeV−3, respectively. All values but that for 102Ru agree with the global average of (20 ± 6) × 10−9 MeV−3. The average [Formula: see text] of 96Mo observed is 247 ± 175 e2 fm4 MeV−1.

scholarly journals Study of a collimation method as a nondestructive diagnostic diagnostic technique by PGNAA for salt distribution in concrete structures at RANS

2020 ◽  
Vol 231 ◽  
pp. 05007 ◽  
Author(s):  
Yasuo Wakabayashi ◽  
Takao Hashiguchi ◽  
Yuichi Yoshimura ◽  
Maki Mizuta ◽  
Yujiro Ikeda ◽  
...  
Keyword(s):  
Neutron Capture ◽  
Diagnostic Technique ◽  
Steel Corrosion ◽  
Prompt Gamma ◽  
Neutron Capture Reaction ◽  
Γ Rays ◽  
Γ Ray ◽  
A New Technique ◽  
Gamma Neutron Activation ◽  
Salt Distribution

To meet strong demand for realizing an effective tool to diagnose salt distribution in concrete infrastructures, we have started a development of a new technique using a prompt gamma neutron activation analysis (PGNAA) at the RIKEN accelerator-driven compact neutron source (RANS). So far, by applying PGNAA we have experimentally confirmed that neutrons from RANS can detect small enough amounts of chlorine within the marginal concentration of around 1.2 kg/m3 to involve steel corrosion. In this study, we have proposed two methods to derive the salt depth profile which is critical information of steel corrosion start. The first one utilizes a difference in the intensity ratio of two different γ-ray energies of interest, which is depending on the depth where the neutron capture reaction arises inside the concrete. The second is called the collimator method that measure γ-rays coming through a collimator around detector. Detection of γ-ray associated with 35Cl coming from the assembly of concrete has been also simulated with conditions of neutrons from RANS and a collimator. The feasibility of the method was discussed.

NEUTRON CAPTURE GAMMA RAYS FROM FLUORINE, MAGNESIUM, GALLIUM, BROMINE, AND HAFNIUM

1957 ◽  
Vol 35 (12) ◽  
pp. 1361-1379 ◽  
Author(s):  
P. J. Campion ◽  
G. A. Bartholomew
Keyword(s):  
Energy Range ◽  
Gamma Rays ◽  
Ground State ◽  
Neutron Capture ◽  
State Transition ◽  
High Energy ◽  
The Other ◽  
Ground State Transition ◽  
Γ Rays ◽  
Γ Ray

The neutron capture γ-ray spectra of fluorine, magnesium, gallium, bromine, and hafnium have been studied in the energy range above 3 Mev. In fluorine four γ-rays and in magnesium 12 γ-rays have been detected in addition to those previously observed. Most of these new radiations can be assigned to the known level schemes of the product nuclei. The spectrum obtained for each of the other elements is complex with only a few of the high energy γ-rays resolved, and in each case the γ-ray of highest energy is very weak and difficult to distinguish from the background. The most energetic gallium γ-ray at 7.73 ± 0.02 Mev. may be emitted in the direct ground state transition in Ga70 while the 7.879 ± 0.013 Mev. γ-ray from bromine probably corresponds to the ground state transition in Br80. In hafnium none of the observed γ-rays can be identified with a ground state transition in any of the isotopes.

NEUTRON CAPTURE γ-RAYS FROM HEAVY ODD-CHARGE NUCLEI

1953 ◽  
Vol 31 (7) ◽  
pp. 1025-1050 ◽  
Author(s):  
G. A. Bartholomew ◽  
B. B. Kinsey
Keyword(s):  
Neutron Capture ◽  
High Energy ◽  
Γ Rays ◽  
Γ Ray

The neutron capture γ-ray spectra of arsenic, niobium, rhodium, silver, indium, antimony, praseodymium, tantalum, gold, and thallium are described. The energies and intensities of the strongest high energy γ-rays are given for each element.

NEUTRON CAPTURE γ-RAYS FROM HEAVY EVEN-CHARGE NUCLEI

1953 ◽  
Vol 31 (7) ◽  
pp. 1051-1086 ◽  
Author(s):  
B. B. Kinsey ◽  
G. A. Bartholomew
Keyword(s):  
Neutron Capture ◽  
High Energy ◽  
Γ Rays ◽  
Γ Ray

The neutron capture γ-ray spectra of the elements selenium, strontium, zirconium, molybdenum, cadmium, tin, barium, samarium, gadolinium, wolfram, platinum, and mercury are described. The energies and intensities of the strongest high energy γ-rays are given for each element.

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