THE (γ, n) AND (γ, p) CROSS SECTIONS OF ARGON40

1954 ◽  
Vol 32 (9) ◽  
pp. 593-598 ◽  
Author(s):  
D. McPherson ◽  
E. Pederson ◽  
L. Katz
Keyword(s):  
Cross Section ◽  
Photon Energy ◽  
Cross Sections ◽  
Integrated Cross Section ◽  
Peak Value

The (γ, n) and (γ, p) cross sections in A40 have been measured as a function of photon energy from threshold to 24 Mev. The (γ, n) cross section was found to have a peak value of 38 mbarns at 20 Mev. and an integrated cross section of 0.35 Mev-barn. These values for the (γ, p) cross section were found to be 120 mbarns at > 25 Mev. and 0.54 Mev-barn respectively. In spite of the higher (γ, p) threshold, it was found that the two cross sections were equal at 19.5 Mev. and above this energy the (γ, p) cross section became larger. This interesting result is discussed.

PHOTONEUTRON CROSS SECTIONS IN SILICON AND CALCIUM

1953 ◽  
Vol 31 (1) ◽  
pp. 70-77 ◽  
Author(s):  
R. G. Summers-Gill ◽  
R. N. H. Haslam ◽  
L. Katz
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Neutron Yield ◽  
Threshold Energy ◽  
Threshold Effect ◽  
Monitoring Method ◽  
Dose Monitoring ◽  
Γ Rays ◽  
Integrated Cross Section ◽  
Peak Value

Using the dropping apparatus and dose monitoring method previously reported, the cross sections for the reactions Si28(γ, n)Si27 and Ca40(γ, n)Ca39 have been measured by detecting positron activities in the residual nuclei. The Si28(γ, n)Si27 cross section has a peak value of 21 mbarns at 20.9 Mev. and an integrated cross section to 24 Mev. of 0.070 Mev-barns. The threshold energy is 16.9 ± 0.1 Mev. The Ca40(γ, n)Ca39 cross section has a peak value of 15 mbarns at 19.3 Mev. and an integrated cross section to 24 Mev. of 0.065 Mev-barns. The threshold is 15.8 ± 0.1 Mev.A comparison of our results with the neutron yield measurement of Price and Kerst at 18 and 22 Mev. gives good agreement. A further comparison with the neutron yield work of Baldwin and Elder is made.The sharp discontinuity in (γ, n) yields using lithium γ rays observed by Wäffler and Hirzel is explained as a threshold effect. Integrated cross sections increase more or less smoothly with Z.In addition, improved values for the half-lives of the residual nuclei Si27 and Ca39 have been measured. These are 4.45 ± 0.05 and 1.00 ± 0.03 sec. respectively.

THE MEASUREMENT OF PHOTONUCLEAR CROSS SECTIONS IN ISOTOPES LEADING TO SHORT-LIVED DECAY PRODUCTS

1952 ◽  
Vol 30 (3) ◽  
pp. 257-269 ◽  
Author(s):  
R. N. H. Haslam ◽  
R. G. Summers-Gill ◽  
E. H. Crosby
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Half Life ◽  
Half Width ◽  
Reaction Threshold ◽  
Parent Materials ◽  
Dosage Rate ◽  
Decay Products ◽  
Integrated Cross Section ◽  
Peak Value

A dropping apparatus, including a new means of dosage rate monitoring, has been designed to allow the observation of short-lived activities produced by betatron irradiation of various parent materials. The photonuclear cross section for the reaction S32(γ, n)S31 has been measured by this means. The cross section has a peak value of 24.6 millibarns at 20.1 ± 0.5 Mev., a half width of 4.5 Mev., and an integrated cross section of 0.12 Mev-barns. The reaction threshold was found to be 15.0 ± 0.1 Mev. The experiment has also yielded a new half life for S31 − 2.66 ± 0.03 sec.

Angular distributions and cross sections of the photoneutron reaction in 9Be in the photon energy region 18–26 MeV

1977 ◽  
Vol 55 (4) ◽  
pp. 364-369 ◽  
Author(s):  
A. Buchnea ◽  
R. G. Johnson ◽  
K. G. McNeill
Keyword(s):  
Cross Section ◽  
Photon Energy ◽  
Cross Sections ◽  
Energy Region ◽  
Angular Distributions ◽  
Photoneutron Reaction ◽  
Integrated Cross Section

The 9Be(γ,n0)8Be and 9Be(γ,n1)8Be reactions were studied in the photon energy region 18 to 26 MeV. The integrated cross section of the (γ,n0) reaction was found to be less than 0.1 MeV mb in this energy region. The integrated cross section for the (γ,n1) reaction in the energy region is 2.4 ± 0.4 MeV mb, which is 10 to 15% of the total photoneutron cross section. The measured angular distributions for the (γ,n1) reaction are consistent with the population of 3/2+ and 5/2+ states of 9Be. These results are consistent with slightly re-interpreted predictions of Majling, Kukulin, and Smirnov.

PHOTONEUTRON THRESHOLD AND CROSS SECTION FOR 71Lu175

1958 ◽  
Vol 36 (4) ◽  
pp. 415-418 ◽  
Author(s):  
H. J. King ◽  
L. Katz
Keyword(s):  
Cross Section ◽  
Neutron Yield ◽  
Giant Resonance ◽  
Threshold Energy ◽  
Half Width ◽  
Bremsstrahlung Energy ◽  
Resonance Cross Section ◽  
Integrated Cross Section ◽  
Peak Value

The neutron yield resulting from photoneutron reactions in Lu175 has been measured as a function of peak bremsstrahlung energy up to 23 Mev. The threshold energy for this reaction was found to be 7.77 ± 0.05 Mev. The giant resonance cross section has a peak value of 225 millibarns at 16 Mev., a half-width of 8.4 Mev., and an integrated cross section to 23 Mev. of 1.9 Mev-barns.

Photoneutron Cross Sections in 14N

1972 ◽  
Vol 50 (15) ◽  
pp. 1689-1696 ◽  
Author(s):  
R. W. Gellie ◽  
K. H. Lokan ◽  
N. K. Sherman ◽  
R. G. Johnson ◽  
J. I. Lodge
Keyword(s):  
Excited States ◽  
Cross Section ◽  
Cross Sections ◽  
Neutron Emission ◽  
Giant Resonance ◽  
Sequential Decay ◽  
Dipole Resonance ◽  
Intermediate States ◽  
Integrated Cross Section ◽  
High Degree

Photoneutron distributions from 14N have been obtained by time-of-flight methods, for bremsstrahlung end-point energies increasing in 2 MeV steps from 15.5 to 29.5 MeV. A large part of the neutron yield is associated with the sequential decay of 14N to 12C, through well-defined intermediate states of 13C, at 7.55, 8.86, and 11.80 MeV, which are unstable against neutron emission. The (γ,n0) cross section for neutron emission to the ground state of 13N is found to agree very closely with the corresponding (γ,p0) cross section, implying a high degree of isospin purity for the giant dipole resonance of 14N. It is observed that the decay of the giant resonance proceeds freely through those odd-parity excited states of the A = 13 nuclei which are single hole states formed by the removal of a p-shell nucleon from the parent 14N.The integrated cross section for all neutron-producing interactions is found to be 88 ± 5 MeV mb.

scholarly journals Single photoionization of the Kr-like Rb ii ion in the photon energy range 22–46.0 eV

2019 ◽  
Vol 486 (1) ◽  
pp. 245-250 ◽  
Author(s):  
Brendan M McLaughlin ◽  
James F Babb
Keyword(s):  
Cross Section ◽  
Photon Energy ◽  
Cross Sections ◽  
Large Scale ◽  
Experimental Studies ◽  
Photoionization Cross Section ◽  
Theoretical Work ◽  
Matrix Approximation ◽  
Theoretical Cross Section ◽  
R Matrix

Abstract Single photoionization cross-sections for Kr-like Rb+ ions are reported in the energy (wavelength) range from 22 (564 Å) to 46 eV (270 Å). Theoretical cross-section calculations for this trans-Fe element are compared with measurements from the ASTRID radiation facility in Aarhus, Denmark and from the dual laser plasma technique, at respectively 40 and 35 meV FWHM energy resolution. In the photon energy region 22–32 eV the spectrum is dominated by excitation auto-ionizing resonance states. Above 32 eV the cross-section exhibits classic Fano window resonances features, which are analysed and discussed. Large-scale theoretical photoionization cross-section calculations, performed using a Dirac Coulomb R-matrix approximation are benchmarked against these high-resolution experimental results. Comparison of the theoretical work with the experimental studies allowed the identification of resonance features and their parameters in the spectra in addition to contributions from excited metastable states of the Rb+ ions.

scholarly journals DPS mechanism for associated $$c\bar{c} b\bar{b}$$ production in AA UPCs

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Edgar Huayra ◽  
Emmanuel G. de Oliveira ◽  
Roman Pasechnik
Keyword(s):  
Production Process ◽  
Cross Section ◽  
Photon Energy ◽  
Cross Sections ◽  
Effective Cross Section ◽  
Double Parton Scattering ◽  
Quark Pairs ◽  
Numerical Predictions ◽  
Energy Dependent ◽  
Parton Scattering

Abstract We discuss the associated $$c\bar{c}$$cc¯ and $$b\bar{b}$$bb¯ quark pairs production in the double-parton scattering (DPS) process in ultraperipheral (UPCs) AA collisions. We derive an analogue of the inclusive DPS pocket formula and the photon-energy dependent effective cross section considering an overlap between the hard SPS scatterings. We provide numerical predictions for the DPS cross sections for the $$c\bar{c}b\bar{b}$$cc¯bb¯ production process at the typical energies of AA UPCs at the LHC and FCC colliders and also characterize the A dependence of the total UPC DPS cross section.

CROSS SECTION FOR THE REACTION Be9(γ, p)Li8

1953 ◽  
Vol 31 (2) ◽  
pp. 210-217 ◽  
Author(s):  
R. N. H. Haslam ◽  
L. Katz ◽  
E. H. Crosby ◽  
R. G. Summers-Gill ◽  
A. G. W. Cameron
Keyword(s):  
Cross Section ◽  
Half Width ◽  
X Ray ◽  
Intermittent Operation ◽  
Integrated Cross Section ◽  
The Cross ◽  
Peak Value

The reaction Be9(γ, p)Li8has been investigated by detecting the 0.88 sec. Li8 β-activity, by the use of a cycling apparatus which allows intermittent operation of the betatron, counting taking place during the periods of no X-ray yield. The cross section for the reaction has a peak value of 2.72 mbarns at 22.2 Mev., a half-width of 4.7 Mev., and the integrated cross section to 26 Mev. is 0.013 Mev-barns.

Sum Rule Photo-Disintegration Cross Sections for the Deuteron with Velocity-Dependent and Hard-Core Potentials

1971 ◽  
Vol 49 (17) ◽  
pp. 2211-2214 ◽  
Author(s):  
S. S. Raghavan ◽  
B. K. Srivastava
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Sum Rules ◽  
Hard Core ◽  
Dipole Approximation ◽  
Sum Rule ◽  
Core Potential ◽  
Cross Section Formula ◽  
Dependent Potential ◽  
Integrated Cross Section

We apply the sum rules of Levinger and Bethe to calculate the integrated cross section[Formula: see text]and the bremsstrahlung-weighted cross section[Formula: see text]for the deuteron in the dipole approximation. In our calculations we use (i) Nestor's velocity-dependent potential and (ii) Reid's hard-core potential. Our results for σint and σb obtained with the velocity-dependent potential of Nestor and the hard-core potential of Reid agree well with experiments.

Photodisintegration cross sections of the deuteron

1977 ◽  
Vol 55 (2) ◽  
pp. 158-163 ◽  
Author(s):  
M. L. Rustgi ◽  
O. P. Rustgi ◽  
T. S. Sandhu
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Short Distance ◽  
Tensor Force ◽  
The Other ◽  
State Probability ◽  
Spin Orbit ◽  
Local Potentials ◽  
Integrated Cross Section

Employing a variety of local static potentials, the bremsstrahlung-weighted and integrated cross sections for the photodisintegration of the deuteron are calculated. The effect of variation of the tensor force in the two-nucleon Yale potential in a manner as to affect only the D state probability of the deuteron, while leaving the values of the other two-body observables unchanged, is studied. It is found that though the contribution of the central, tensor, and spin–orbit components of the two-nucleon potentials to the integrated cross section may vary significantly, the integrated cross section does not change by more than a few percent. The sensitivity of the integrated cross section to the short-distance features of the two-nucleon local potentials is also studied.

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