Monoenergetic Neutron Techniques in the 10- to 30-Mev Range

Fowler, J.L.; Brolley, J.E.

doi:10.1103/revmodphys.28.103

Cited by 193 publications

(14 citation statements)

References 137 publications

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“…Variation of neutron energy was achieved by selection of the deuteron energy as well as by irradiation of samples placed at various angles about the target. 10 The experimental arrangement was such that samples could be placed on a circular arc of 2-in. radius at any angle from 0° to 160° with respect to the incident deuteron beam.…”

Section: Experimental Procedures and Resultsmentioning

confidence: 99%

Excitation Function forZn64(n, 2n)Zn63
Koehler
¹
,
Alford
²

1960
Phys. Rev.
11
1
0
0
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The excitation function for Zn 64 (»,2»)Zn, 68 has been measured for neutron energies from 12.2 to 18.1 Mev by an activation method. An absolute cross section has been obtained by using the previously measured value of 167±11 mb at 14.4 Mev. Above threshold, the cross section is found to increase rapidly with neutron energy reaching a value of 337 mb at 18.1 Mev. A cross-section curve computed on the basis of statistical theory is shown for comparison.

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Section: Experimental Procedures and Resultsmentioning

confidence: 99%

Excitation Function forZn64(n, 2n)Zn63
Koehler
¹
,
Alford
²

1960
Phys. Rev.
11
1
0
0
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“…For each irradiation an average neutron energy was calculated using the tables of Fowler and Brolley (14). The neutron energy is a direct function of the deuteron energy and the angle between the incident deuteron beam and the emitted neutron.…”

Section: Resultsmentioning

confidence: 99%

Th²³² (n,2n)Th²³¹ CROSS SECTION FROM THRESHOLD TO 20.4 MEV

Butler¹,

Santry²

1961

Can. J. Chem.

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The excitation curve for the reaction Th232 (n,2n) Th23l has been measured by the activation method from the threshold energy, 6.34 Mev, to 20.4 Mev, relative to the known cross section for the S32(n,p)P32 reaction. Monoenergetic neutrons were obtained from the D ( d , n ) He3 and T (d,n) He4 reactions employing a Tandem Van de Graaff accelerator. From threshold to 9.0 Mev, the (n,2n) cross section rises rapidly, reaching its maximum value of 1.88f 0.09 barns in the region of 9.5 to 11.0 Mev. Above 11.5 Mev the (n,2n) cross section decreases due t o competition of the (n,3n) and (n,2nf) reactions and a t 20.4 Mev it has a value of 0.226f 0.01j barns. INTRODUCTIONAlthough many measurelnents of fast neutron cross sections (n,2n), (n,p), and (n,a) have been made with 14-Mev neutrons, relatively few data have beell published over a range of neutron energies for which these reactions have appreciable cross sections. Due to the scarcity of data on neutron cross sections as a function of energy and the lack of agreement among existing results, a program has been initiated to measure fast neutron cross sections from threshold energies to about 21 Mev. These cross sections will be determined whenever possible with a n accuracy of f 5%.The recent development of the Tandem Van de Graaff accelerator now makes it possible to obtain measurements of fast neutron cross sections over a greater energy range.By accelerating deuterons to a precise energy, the reactions D (d,n) He3 and T (d,n) He4 can be used t o produce monoenergetic neutrons a t any energy from about 5 t o 21 Mev.Results have been published on the cross section for absorption reactions of fast neutrons with Th232. T h e (nly) reaction has been measured up to 14 Mev (1) and the fission cross section has been measured by several investigators from threshold energies up to 11 Mev (1, 2) and a t 14.5 Mev (1, 3). However, data on the significant (n,2n) cross section are only available a t a few energies (4, 5). T h e present investigation was undertaken t o determine the cross section for the reaction ThZ3"n,2n) ThZ3l from threshold, 6.34 Mev, to 20.4 Mev. The reaction (n,p) P3? was used to monitor the fast neutron flux. After the irradiation, thorium was purified radiochemically, and the as well as the P32 produced were determined by absolute beta counting. The (n,2n) cross section a t a particular neutron energy was then calculated from the ThZ3l-and Pa?-activity measurements and the lcnown cross section for the sulphur (n,p) reaction (6). E X P E R I M E N T A L METHOD A . Neutron SourcesNeutrons with energies froin 6 t o 11.6 Mev were obtained from the reaction D (d,n) He3 employing the Chalk River Tandem Van de Graaff accelerator. A gas target cell similar to that described by Johnson and Banta (7) and illustrated in the lower part of Fig. 1 was used to contain the deuterium. The bombarding deuteron beam was magnetically analyzed, focused with a set of quadrupole magnets, and collimated by a 0.125-in. gold aperture. Deuterons scattered off the edge of the...

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“…In the production of 3.0 Mev neutrons, there are both energy and intensity losses as a function of the center of mass scattering angle shown in Fig. 2.1 [Fowler and Brolley (1956)]. …”

Section: Phantom Arrangement and Reference Gridmentioning

confidence: 99%

EXPERIMENTALLY DETERMINED PROTON-RECOIL SPECTRA IN TISSUE-EQUIVALENT MATERIAL FROM 3- AND 15-MeV NEUTRONS.

Stone¹,

Thorngate²

1967

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Monoenergetic Neutron Techniques in the 10- to 30-Mev Range

Cited by 193 publications

References 137 publications

Excitation Function forZn64(n, 2n)Zn63
Koehler
¹
,
Alford
²

1960
Phys. Rev.
11
1
0
0
View full text Add to dashboard Cite

Excitation Function forZn64(n, 2n)Zn63
Koehler
¹
,
Alford
²

1960
Phys. Rev.
11
1
0
0
View full text Add to dashboard Cite

Th²³² (n,2n)Th²³¹ CROSS SECTION FROM THRESHOLD TO 20.4 MEV

EXPERIMENTALLY DETERMINED PROTON-RECOIL SPECTRA IN TISSUE-EQUIVALENT MATERIAL FROM 3- AND 15-MeV NEUTRONS.

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Monoenergetic Neutron Techniques in the 10- to 30-Mev Range

Cited by 193 publications

References 137 publications

Excitation Function forZn64(n, 2n)Zn63Koehler1, Alford2 1960Phys. Rev.11100View full textAdd to dashboardCite

Excitation Function forZn64(n, 2n)Zn63Koehler1, Alford2 1960Phys. Rev.11100View full textAdd to dashboardCite

Th232 (n,2n)Th231 CROSS SECTION FROM THRESHOLD TO 20.4 MEV

EXPERIMENTALLY DETERMINED PROTON-RECOIL SPECTRA IN TISSUE-EQUIVALENT MATERIAL FROM 3- AND 15-MeV NEUTRONS.

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Excitation Function forZn64(n, 2n)Zn63
Koehler
¹
,
Alford
²

1960
Phys. Rev.
11
1
0
0
View full text Add to dashboard Cite

Excitation Function forZn64(n, 2n)Zn63
Koehler
¹
,
Alford
²

1960
Phys. Rev.
11
1
0
0
View full text Add to dashboard Cite

Th²³² (n,2n)Th²³¹ CROSS SECTION FROM THRESHOLD TO 20.4 MEV