Photoprotons from lithium and carbon with 100 MeV bremsstrahlung

Matthews, J.; Bertozzi, W.; Kowalski, S.; Sargent, C. P.; Turchinetz, W.

doi:10.1016/0375-9474(68)90084-5

Cited by 41 publications

(8 citation statements)

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“…The calculation of the differential production cross section on basis of the quasi-deuteron model has been carried out in the same way as described by Matthews [13]. The cross section for the production of neutrons of energy E,, and angle 0," by one incident electron may be written…”

Section: Resultsmentioning

confidence: 99%

“…At photon energies below 100 MeV, one sees from the experiments [12][13][14][15], that here the contributions (7,p) and (7, n) from the direct H. J. yon Eyss and G. Ltihrs single-particle mechanism are comparable in size to those from the (~, np) process. The results of Manuzio [16], $anzone [17] and the neutron measurements of Schier and Schoch [18] performed at different electron energies on 12C and 160, show that the production cross sections for nucleons from the single-particle mechanism decrease so fast with increasing v-energy, that above Er= 100 MeV the nucleons originating from the single-particle process are negligible compared with those from the (V, np) process.…”

Section: Introductionmentioning

confidence: 91%

“…For comparison: Alsmiller and Gabriel [33] assumed for the calculation of the photo-nucleon spectra from light and heavy nuclei a Gaussian distribution for the nucleons inside the nucleus with a 1/e-value of 15 MeV (~168 MeV/c). Recent experimental investigations [7,13,34] on 12C and 160 yield values for between 100 and 120 MeV/c whilst in earlier publications [35][36][37], a-values between 168 and 194 MeV/c have been used, even for such light nuclei as beryllium, carbon and oxygen.…”

Section: Differential Production Cross Sections In Relation To Electrmentioning

confidence: 98%

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Photoproduction of high-energy neutrons in thick targets by electrons in the energy range 150 to 270 MeV

Eyss

Lührs

1973

Z. Physik

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Photoneutron spectra with energies greater than 12 MeV produced by electrons incident on a thick lead target have been measured for primary electron energies between 150 and 266 MeV and at a fixed angle of 90 ~ to the beam axis. Measurements of the neutron yield have furthermore been performed at a primary energy of 234 MeV as a function of target depth for the same lead target and as a function of the mass number for C, A1, Cu, Cd and Pb targets. The results were obtained with three independent neutron detectors: two proton recoil counters and one time-of-flight set-up. The high-energy regions of the spectra are compared with the predictions of the phenomenological quasi-deuteron model and a satisfactory agreement in shape and scale of the spectra is found. Additional high-energy neutrons from pion reabsorption processes were observed at electron energies of 234 and 266 MeV.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 91%

Section: Differential Production Cross Sections In Relation To Electrmentioning

confidence: 98%

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Photoproduction of high-energy neutrons in thick targets by electrons in the energy range 150 to 270 MeV

Eyss

Lührs

1973

Z. Physik

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“…In their paper, Gabriel and Alsmiller show the results of a PICA analysis of photo-proton data for carbon irradiated with bremsstrahlung of end-point energy 110 MeV (the data are taken from [7] and [8] Fits of similar quality are found at 70 ~ lab with the same parameter value the range of possible discrepancy in the experimental data and we consider that these comparisons strongly suggest that the model can fit photo-proton data from any one element with one and the same value of quasi-deuteron constant for bremsstrahlung of end-point energies up to about 600MeV. Simpler models [4], on the other hand, demand an increase in the effective value of L in the same energy-region by factors of ~3 (40 ~ and ~2 (70 ~ That agreement with experimental data is found up to such high end-point energies is rather surprising.…”

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confidence: 99%

Photo-protons from high-energy bremsstrahlung

1975

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Abstract. Recent results on the yields of high-energy photo-protons from both bremsstrahlung and monochromatic photons incident mainly on carbon are compared with calculations using the Gabriel-Alsmiller model of high-energy photo-induced reactions. Good agreement is found for photons of energies up to 600 MeV.Recently, extensive sets of data on the cross-sections for nuclei from lithium to gold to produce high-energy photo-protons have become available [1,2]. In [1], data at an end-point energy of 400 MeV were given, while in [2], proton yields mainly from carbon irradiated with bremsstrah~ungofend-point energies between 125 and 1000MeV were listed, as were some data obtained by a "'photon difference" method. Some of the results of [1] have been analyzed in [3], in terms of the "quasi-deuteron" model as formulated by Matthews [4] and of the intra-nuclear cascade model (PICA) of Gabriel and Alsmiller [5]. In this paper, analysis of the data in [1] and [2] is extended, using the latter model. Three specific matters are examined:I. The earlier analysis indicated that, to obtain agreement with experiment, it was necessary to renormalize that part of the flux in the Gabriel-Alsmiller model which originates via the quasi-deuteron mechanism. The values of the quasi-deuteron constant, L, given by fits to the experimental data were _~ 6 for C, ~-8 for Cu and ___13 for Au. Although there thus appears to be a tendency for the value of L to increase with increasing atomic number, this conclusion depends largely on the value for gold. This is, however, the least well-determined of the values, partly due to the fact that the statistical accuracy of the calculations was not good and partly to the fact that the results for gold are not particularly sensitive to the exact value of quasi-deuteron constant used. (Few of the particles photo-produced in gold are protons.) Additional calculations have now been performed for Be and Ag, for comparison with the data of [I]. The calculated values have, as before, been fitted to experiment by treating the value of L as if it were a free parameter. The results are shown in Fig. 1. The values indicated by the comparison are L = 5 +1 for Be and L=10_+2 for Ag, (As in the earlier analysis, these values are determined by the value of L giving the best visual fit to the experimental data. The errors quoted in the values of L do not take into account any errors in the input data, e.g. in the values of the cross-sections for deuteron photo-disintegration. These are usually smaller than the statistical errors in P1CA calculations.) With the present results, PICA analyses have now been performed for six of the elements for which data were reported in [1] (A1 has been studied by Gabriel who finds L=7.2 [6]). All the analyses confirm the trend reported in [1], that, within the framework of the Gabriel-Alsmiller model, the value of quasi-

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“…'3 The investigation of the existence and relative importance of each process is therefore the main experimental prob-7 W. P. Mason, Phys. Rev.…”

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confidence: 99%