E3 Coulomb excitation of 19F

1969 ◽  
Vol 47 (21) ◽  
pp. 2335-2342 ◽  
Author(s):  
T. K. Alexander ◽  
O. Häusser ◽  
K. W. Allen ◽  
A. E. Litherland
Keyword(s):  
Cross Section ◽  
Ground State ◽  
Gamma Ray ◽  
Excitation Cross Section ◽  
Coulomb Excitation ◽  
Thick Target ◽  
Transition Strength ◽  
Average Value ◽  
Target Yield ◽  
Model Predictions

The E3 matrix element connecting the ground state with the 5/2−, 1346-keV level in 19F has been measured by projectile excitation of a 19F beam and observation of the 1236-keV de-excitation gamma ray in Ge(Li) detectors. The thick-target yield of the 1236-keV gamma ray was 1.6, 6.0, 9.8, and 23 gammas per 1010 projectiles at bombarding energies of 22, 25, 26, and 28 MeV, respectively. The average value of the strength of the E3 transition deduced from these measurements is [Formula: see text] In addition, the E2 Coulomb-excitation cross section of the 1554-keV level was measured and the reduced transition strength of the E2 transition from the 1554-keV level to the ground state was found to be 6.8 ± 0.7 W.u. Comparisons are made with model predictions.

Coulomb excitation of 24Mg with 35Cl ions

1969 ◽  
Vol 47 (18) ◽  
pp. 1929-1940 ◽  
Author(s):  
D. Pelte ◽  
O. Häusser ◽  
T. K. Alexander ◽  
H. C. Evans
Keyword(s):  
Quadrupole Moment ◽  
Cross Section ◽  
Ground State ◽  
State Transition ◽  
Gamma Ray ◽  
Coulomb Excitation ◽  
Absolute Cross Section ◽  
Ground State Transition ◽  
Section Measurement ◽  
Anisotropy Measurement

The Coulomb excitation of a thick 24Mg target was studied with 35Cl ions of 61, 57, and 52 MeV. The absolute cross section and the anisotropy of the angular distribution of the ground state transition from the 1.369-MeV state in 24Mg was measured, and their dependence on B(E2) and the quadrupole moment, Q, of the 1.369-MeV state was calculated. A B(E2) of 24.5 ± 2.2 Weisskopf units (W.u.) was deduced from the line shape of the 1.369-MeV gamma ray observed with a 40 cm3 Ge(Li) detector. The quadrupole moment determined from the anisotropy measurement was Q = −0.38 ± 0.16 b. From the cross-section measurement, Q = −0.47 ± 0.19 b was obtained using B(E2) = 24.5 ± 2.2 W.u. The dependence of this value of Q on B(E2) is discussed.

Study of the Ep = 1.724 MeV Resonance in the 27Al(p, γ) 28Si Reaction

1971 ◽  
Vol 49 (6) ◽  
pp. 685-703 ◽  
Author(s):  
S. T. Lam ◽  
A. E. Litherland ◽  
R. E. Azuma
Keyword(s):  
Ground State ◽  
Gamma Ray ◽  
Branching Ratios ◽  
Thick Target ◽  
Angular Distributions ◽  
Transition Strength ◽  
Proton Capture ◽  
A Value ◽  
28Si Reaction ◽  
Relative Measurements

The 13.245 MeV level in 28Si has been populated by resonant proton capture at 1.724 MeV in the 27Al(p,γ)28Si reaction. Gamma-ray angular distributions and linear polarizations have been measured respectively with a coaxial and a planar Ge(Li) counter. Branching ratios have been extracted from the angular distributions. Spins have been assigned to the levels of 28Si with the help of the angular distribution and linear polarization results. The spin and parity of the 13.245 and 9.699 MeV levels are most probably 5− with T = 1 and 0 respectively. The assignment Jπ = 4− for the 8.411 MeV level is in agreement with the present data. A spin and parity of 3− for both the 13.245 and 9.699 MeV levels also fits the data but with more adjustable parameters. Arguments are presented to show that these assignments are unlikely. Relative measurements of the gamma-ray yields from a thick target give a value of (7.5 ± 1.5) eV for (2J + 1)ΓγΓp/Γ of the resonance. The M1 transition strength between the 13.245 and the 9.699 MeV levels is then deduced to be (0.7 ± 0.15) W.u. The known properties of the 9.699 MeV level suggest that it may be associated with an E5 oscillation of the ground state of 28Si.

scholarly journals Cross section and reaction rate of determined from thick target yield measurements

2014 ◽  
Vol 922 ◽  
pp. 112-125 ◽  
Author(s):  
Gy. Gyürky ◽  
M. Vakulenko ◽  
Zs. Fülöp ◽  
Z. Halász ◽  
G.G. Kiss ◽  
...  
Keyword(s):  
Cross Section ◽  
Reaction Rate ◽  
Thick Target ◽  
Thick Target Yield ◽  
Target Yield

High-Purity Germanium Technology for Gamma-Ray and X-Ray Spectroscopy

1993 ◽  
Vol 302 ◽  
Author(s):  
L.S. Darken ◽  
C. E. Cox
Keyword(s):  
Cross Section ◽  
Gamma Rays ◽  
Ground State ◽  
High Purity ◽  
Gamma Ray ◽  
Capture Rate ◽  
X Rays ◽  
Hole Capture ◽  
High Purity Germanium ◽  
Energy Gamma

ABSTRACTHigh-purity germanium (HPGe) for gamma-ray spectroscopy is a mature technology that continues to evolve. Detector size is continually increasing, allowing efficient detection of higher energy gamma rays and improving the count rate and minimum detectable activity for lower energy gamma rays. For low-energy X rays, entrance window thicknesses have been reduced to where they are comparable to those in Si(Li) detectors. While some limits to HPGe technology are set by intrinsic properties, the frontiers have historically been determined by the level of control over extrinsic properties. The point defects responsible for hole trapping are considered in terms of the “standard level” model for hole capture. This model originates in the observation that the magnitude and temperature dependence of the cross section for hole capture at many acceptors in germanium is exactly that obtained if all incident s-wave holes were captured. That is, the capture rate is apparently limited by the arrival rate of holes that can make an angular-momentum-conserving transition to a s ground state. This model can also be generalized to other materials, where it may serve as an upper limit for direct capture into the ground state for either electrons or holes. The capture cross section for standard levels σS.L. is given bywhere g is the degeneracy of the ground state of the center after capture, divided by the degeneracy before capture. Mc is the number of equivalent extrema in the band structure for the carrier being captured, mo is the electronic mass, m* is the effective mass, and T is the temperature in degrees Kelvin.

Lifetimes of States in 29Si, 27Al, and 26Mg

1971 ◽  
Vol 49 (23) ◽  
pp. 2886-2897 ◽  
Author(s):  
A. B. McDonald ◽  
T. K. Alexander ◽  
O. Häusser ◽  
G. T. Ewan
Keyword(s):  
Doppler Shift ◽  
Line Shape ◽  
Coulomb Excitation ◽  
Thick Target ◽  
Distance Method ◽  
Model Predictions ◽  
Doppler Shift Attenuation ◽  
Recoil Distance ◽  
Doppler Shift Attenuation Method

The recoil-distance method was used to measure the lifetimes of the 29Si, 3626 keV (7/2−) level (4.2 ± 0.5 ps) from the 12C(19F,npγ)29Si reaction, the 26Mg, 1809 keV (2+) level (0.7 ± 0.3 ps) from the 12C-(19F,αpγ)26Mg reaction, and the 27Al, 843 keV (1/2+) level (45 ± 6 ps) from the 27Al(35Cl,35Cl)27Al Coulomb excitation reaction. The Doppler shift attenuation method was employed to determine the lifetime of the 27Al, 1013 keV (5/2+) level [Formula: see text] from the line shape for thick target Coulomb excitation by 67 MeV 35Cl. The results are compared with model predictions.

Coulomb excitation of 133Cs with protons

1985 ◽  
Vol 63 (4) ◽  
pp. 483-487 ◽  
Author(s):  
K. P. Singh ◽  
D. C. Tayal ◽  
B. K. Arora ◽  
T. S. Cheema ◽  
H. S. Hans
Keyword(s):  
Angular Distribution ◽  
Gamma Ray ◽  
Transition Probabilities ◽  
Coulomb Excitation ◽  
Spin Assignment ◽  
Thick Target ◽  
Angular Distributions ◽  
Distribution Data ◽  
Mixing Ratios ◽  
Reduced Transition Probabilities

Protons of energy 3.2–4.2 MeV have been used to Coulomb excite the states in 133Cs. The thick-target gamma-ray yields and the angular distributions were measured using a 50 cm3 Ge(Li) detector. The measurements were used to extract the reduced transition probabilities, B (E2) and B(M1), and multipole mixing ratios (δ) for the various transitions. A spin assignment has been made to the 871.8 keV level on the basis of angular distribution data. The results obtained have been compared with those of other authors.

Photoneutron cross sections in 7Li

1977 ◽  
Vol 55 (5) ◽  
pp. 428-433 ◽  
Author(s):  
H. Ferdinande ◽  
N. K. Sherman ◽  
K. H. Lokan ◽  
C. K. Ross
Keyword(s):  
Fine Structure ◽  
Excited State ◽  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
Reasonable Agreement ◽  
Branching Ratio ◽  
Energy Spectra ◽  
Average Value ◽  
First Excited State

Photoneutron energy spectra from 7Li have been measured by time-of-flight methods, for bremsstrahlung end-point energies increasing in 2 MeV steps from 13 to 25 MeV. The ground-state and approximate first-excited-state differential cross sections at 90° have been obtained from 8.5 to 23 MeV. No pronounced fine structure has been observed. The measured branching ratio to the first excited state falls from an average value of 0.70 between 10.3 and 14.5 MeV to an average of 0.29 between 14.5 and 18 MeV, and rises again to an average of 0.38 between 18 and 23 MeV. This behaviour can be explained by a crude theoretical model in which 1p → 2s and 1p → 1d single particle transitions dominate below 18 MeV. The calculation predicts a branching ratio of 0.50 near threshold, falling to 0.23 at higher energies, in reasonable agreement with the experiment. The integrated value of the ground-state cross section up to 23 MeV is about (38.7 ± 3.9) MeV mb, while that for the first excited state is about (17.2 ± 3.4) MeV mb. Together they account for 39% of the exchange-augmented dipole sum of 7Li.

scholarly journals A Monte Carlo approach to calculate the production prerequisites of 124I radioisotope towards the activity estimation

2018 ◽  
Vol 33 (1) ◽  
pp. 68-74 ◽  
Author(s):  
Hamid Azizakram ◽  
Mahdi Sadeghi ◽  
Parviz Ashtari ◽  
Farhad Zolfagharpour
Keyword(s):  
Monte Carlo ◽  
Cross Section ◽  
Reaction Cross ◽  
Thick Target ◽  
Stopping Power ◽  
Simulation Code ◽  
Target Yield ◽  
Reported Data ◽  
Activity Estimation ◽  
Good Agreement

The Monte Carlo simulation code MCNPX has been used to simulate the production of 124I by 124,125Te(p, xn) and 123,124Te(d,xn) reactions to form high activity 124I. For this reason, the TALYS-1.8 and ALICE/ASH codes were used to calculate the reaction cross-section. The optimal energy range of projectile is selected for this production by identifying the maximum cross-section and the minimum impurity due to other emission channels. Target geometry is designed by SRIM code based on stopping power calculations with identical dimensions as the experimental data. The thick target yield of reactions is predicted because of the excitation functions and stopping power. All of the prerequisites obtained from the above interfaces are adjusted in MCNPX code and the production process is simulated according to benchmark experiments. Thereafter, the energy distribution of proton in targets, the amount of residual nuclei during irradiation, were calculated. The results are in good agreement with the reported data, thus confirming the usefulness and accuracy of MCNPX as a tool for the optimization of other radionuclides production. Based on the results, the 124Te(p,n)124I process seems to be the most likely candidate to produce the 124I in low-energy cyclotrons.

Photoneutron Reactions in 18O

1975 ◽  
Vol 53 (8) ◽  
pp. 786-794 ◽  
Author(s):  
J. D. Allan ◽  
J. W. Jury ◽  
R. G. Johnson ◽  
K. G. McNeill ◽  
J. G. Woodworth ◽  
...  
Keyword(s):  
Excited State ◽  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Ground State ◽  
Energy Spectra ◽  
Continuum State ◽  
Average Value ◽  
First Excited State ◽  
Time Of Flight Spectroscopy

Photoneutron energy spectra from 18O have been measured by time-of-flight spectroscopy at bremsstrahlung endpoint energies from 11 to 18 MeV in 1 MeV steps to obtain the (γ, n0) and (γ, n1) differential cross sections. The ground state photoneutron cross section contains at least 8 major resonances in the region from 10 to 17 MeV and has an average value of 100 μb/sr. The cross section to the first excited state of 17O contains only two major resonances, at 11.4 and 14.4 MeV, and the average cross section in the region from 11 to 16 MeV is about 40 μb/sr. Of particular interest is a resonance at 14.4 MeV which appears to reflect a simple excitation of one of the valence neutrons to the 2p3/2 state. Analysis of the (γ, n0) and (γ, n1) cross sections for this continuum state leads to estimates of the configuration amplitudes of the 2s1/2 and 1d5/2 components of this state to be 0.62 ± 0.06 and 0.78 ± 0.08 respectively and the ratio of the (2s1/2)2 to (1d5/2)2 amplitudes in the ground state of 18O to be 0.39 ± 0.02.

Total Coulomb excitation cross section measurements of radioactive nuclear beams in low energy inverse kinematics

1998 ◽  
Author(s):  
C. J. Barton ◽  
D. S. Brenner ◽  
R. F. Casten ◽  
N. V. Zamfir ◽  
R. L. Gill ◽  
...  
Keyword(s):  
Cross Section ◽  
Inverse Kinematics ◽  
Excitation Cross Section ◽  
Coulomb Excitation ◽  
Low Energy
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