Angular distributions for n-p scattering in the energy range 22.5 to 110 MeV

Scanlon, J.P.; Stafford, G.H.; Thresher, J.J.; Bowen, P.H.; Langsford, A.

doi:10.1016/0029-5582(63)90519-4

Cited by 84 publications

(16 citation statements)

References 12 publications

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“…Previous measurements close to the energy of the present experiment and in the same angular range have been made by Scanlon et al [5] and. by Stahl et al [6].…”

Section: R497supporting

confidence: 50%

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Backward anglen-pdifferential cross section at 96 MeV

et al. 1992

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An accurate measurement of the n-p differential cross section, in the angular range 116' -180', at 96 MeV is reported. Between 150' and 180' the angular distribution is steeper than earlier measurements and potential predictions. The sensitivity of the differential cross section to isospinsinglet, J&4 phase-shift parameters was studied, and it was found that the observed difference at the most backward angles is sensitive mainly to L)3 phase shifts.PACS number(s): 13.75.Cs, 21.30. y The upgraded Gustaf Werner cyclotron at the The Svedberg Laboratory, Uppsala, Sweden, has been equipped with a facility designed to produce wellcollimated and energetically well-defined neutron beams in the energy region from about 50 to 200 MeV. A program to study isovector excitations induced by the (n,p) reaction in various nuclei is at present in progress. The measured (n, p) cross sections are normalized to the n pscattering cross section and therefore precise knowledge of the latter at backward angles is of great importance. Accurate measurements of the n pobservables -are also required for a unique phase-shift description of the nucleonnucleon interaction. The relatively sparse and inaccurate previous measurements of the n-p difFerential cross section in the 100 MeV region motivated a new measurement in the angular range 116' -180' (c.m. ).Since the neutron facility has been extensively presented recently [1], only a brief description will be given here. The neutrons are produced by the Li(p, n) Be reaction, using 100 -200 mg/cm thick discs of lithium, enriched to 99.98% in 7Li. A system of collimators defines the shape of the neutron beam which at the (n, p) target position, 8 m from the neutron production target, has a diameter of 7 cm. A multitarget system, which consists of a stack of thin (n, p) target layers, interspaced by multiwire proportional chambers, is used. In this way it is possible to determine in which layer the reaction occurred, and corrections for the energy loss in the subsequent targets can be applied. The momentum of the charged particles emerging from the reaction target is determined in a spectrometer consisting of a dipole magnet and four drift chambers. The scattering angle is found from the trajectory through the first two drift chambers. The trigger signal is generated by a triple coincidence between two large plastic scintillators, located behind the last drift chamber, and a thin scintillator, positioned immediately after the multitarget box. The neutron timeof-fight (TOF) is measured by using signals from the thin scintillator and the radio frequency of the cyclotron as start and stop signals, respectively. This information is used to reject events from low-energy neutrons in the tail of the neutron spectrum. Together with information on the particle momentum, the pulse heights from the two large scintillators are used for particle identification, enabling separation of protons from other charged particles.Measurements of the iH(n, p) cross section were performed at an incident neutron energy ...

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“…Previous measurements close to the energy of the present experiment and in the same angular range have been made by Scanlon et al [5] and. by Stahl et al [6].…”

Section: R497supporting

confidence: 50%

“…The final experimental values of the differential cross section are listed in Table I [5] and Harvard [6] are also shown.…”

Section: R497mentioning

confidence: 99%

Backward anglen-pdifferential cross section at 96 MeV

et al. 1992

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“…7͑a͒. Thus we give in the figure the data of Stahl and Ramsey ͓28͔, Chih and Powell ͓29͔, Scanlon et al ͓30͔,and Bersbach et al ͓31͔. It can be seen in the figure that the present data are higher at the most backward angles, which indicates a larger steepness at those angles.…”

Section: Resultsmentioning

confidence: 61%

npscattering measurements at 96 MeV

et al. 2001

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The differential np scattering cross section has been measured at 96 MeV in the angular range c.m. ϭ74-180°at the neutron beam facility of the The Svedberg Laboratory in Uppsala. A subset of the data, covering 116-180°, has previously been published. The new, extended angular distribution has been normalized to the experimental total np cross section. Between 150°and 180°, the angular distribution is steeper than for most previous measurements and nucleon-nucleon potential predictions. At 180°, the difference amounts to about 10%, implying serious consequences because of the fundamental importance of this cross section. A value of the charged NN coupling constant consistent with our earlier result at 162 MeV has been extracted from the data.

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“…8 shows data from the present experiment together with other forward np scattering data at 90-100 MeV from the literature, i.e., data from Chih et al [32], Griffith et al [33], Bersbach et al [34], and Scanlon et al [35]. The same panel shows the partial wave analyses Nijmegen PWA93 [29] and SAID SP03 [36].…”

Section: Resultsmentioning

confidence: 77%

“…If we use the full experimental data set, ranging from 20 • to 180 • , but distort the shape of it and subsequently normalize it with the prescription described in this paper, we arrive at slightly different values of the differential cross section. We used a distortion that increases the 0 • and 180 • differential cross sections before normalization with 2%, while keeping the 90 • differential cross section unchanged, and all other cross sections modified with a linear function, i.e., a distortion function looking like the letter V. With such a distortion, the differential cross sections change by up to 1.5% at the worst [29] and SAID SP03 [36] partial wave analyses and with experimental data in the energy region 90-100 MeV from the literature [22,[32][33][34][35]. In the lower panel, the present data are compared with the Nijm93 [37], CD Bonn [38,39], and Paris [40] potentials.…”

Section: Resultsmentioning

confidence: 97%

Forward-angle neutron-proton scattering at 96 MeV

et al. 2005

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The differential np scattering cross section has been measured at 96 MeV in the angular range θ c.m. = 20 • -76 • . Together with an earlier data set at the same energy, covering the angles θ c.m. = 74 • -180 • , a new data set has been formed in the angular range θ c.m. = 20 • -180 • . This extended data set has been normalized to the experimental total np cross section, resulting in a renormalization of the earlier data of 0.7%, which is well within the reported normalization uncertainty for that experiment. A novel normalization technique has been investigated. The results on forward np scattering are in reasonable agreement with theory models and partial wave analyses and have been compared with data from the literature.

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Angular distributions for n-p scattering in the energy range 22.5 to 110 MeV

Cited by 84 publications

References 12 publications

Backward anglen-pdifferential cross section at 96 MeV

Backward anglen-pdifferential cross section at 96 MeV

npscattering measurements at 96 MeV

Forward-angle neutron-proton scattering at 96 MeV

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