Neutron-Proton Scattering in the Energy Range 70 to 170 Mev
01 Mar 1958-Vol. 71, Iss: 3, pp 305-324
TL;DR: The angular distribution of neutrons scattered by protons at effective energies of 96, 130 and 137 Mev and at angles between 19.3° and 78.1° in the centre-of-mass system have been measured using photographic emulsions as mentioned in this paper.
Abstract: The angular distributions of neutrons scattered by protons at effective energies of 96, 130 and 137 Mev and at angles between 19.3° and 78.1° in the centre-of-mass system have been measured using photographic emulsions. The differential cross sections have been normalized to the absolute scale by deducing the energy spectrum of the neutrons. The results confirm that at 130 and 137 Mev the cross sections for scattering at angles within 60° of the forward direction in the centre-of-mass system are less than those for a similar range of angles in the backward direction.
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TL;DR: In this paper, the two-nucleon system at N 3 LO was considered and the spectral function regularization for the multi-pion exchanges was employed to show that the three pion exchange contribution is negligibly small.
560 citations
TL;DR: In this article, the authors presented improved nucleon-nucleon potentials derived in chiral effective field theory up to next to next-next-to-next tonext-leading order, which are able to reduce finite-cutoff artefacts by using an appropriate regularization in coordinate space which maintains the analytic structure of the amplitude.
Abstract: We present improved nucleon-nucleon potentials derived in chiral effective field theory up to next-to-next-to-next-to-leading order. We argue that the nonlocal momentum-space regulator employed in the two-nucleon potentials of previous works (Nucl. Phys. A 747, 362 (2005) and Phys. Rev. C 68, 041001 (2003)) is not the most efficient choice, in particular since it affects the long-range part of the interaction. We are able to significantly reduce finite-cutoff artefacts by using an appropriate regularization in coordinate space which maintains the analytic structure of the amplitude. The new potentials do not require the additional spectral function regularization employed in (Nucl. Phys. A 747, 362 (2005)) to cut off the short-range components of the two-pion exchange and make use of the low-energy constants ci and di determined from pion-nucleon scattering without any fine tuning. We discuss in detail the construction of the new potentials and convergence of the chiral expansion for two-nucleon observables. We also employ a simple approach for estimating the theoretical uncertainty in few-nucleon calculations from the truncation of the chiral expansion that replaces previous reliance on cutoff variation.
283 citations
TL;DR: In this paper, Epelbaum et al. presented improved nucleon-nucleon potentials derived in chiral effective field theory up to next-to-next-tonext-leading order, which are able to significantly reduce finite-cutoff artefacts by using an appropriate regularization in coordinate space.
Abstract: We present improved nucleon-nucleon potentials derived in chiral effective field theory up to next-to-next-to-next-to-leading order. We argue that the nonlocal momentum-space regulator employed in the two-nucleon potentials of Refs. [E. Epelbaum, W. Gloeckle, U.-G. Mei{\ss}ner, Nucl. Phys. A747 (2005) 362], [D.R. Entem, R. Machleidt, Phys. Rev. C68 (2003) 041001] is not the most efficient choice, in particular since it affects the long-range part of the interaction. We are able to significantly reduce finite-cutoff artefacts by using an appropriate regularization in coordinate space which maintains the analytic structure of the amplitude. The new potentials do not require the additional spectral function regularization employed in Ref. [E. Epelbaum, W. Gloeckle, U.-G. Mei{\ss}ner, Nucl. Phys. A747 (2005) 362] to cut off the short-range components of the two-pion exchange and make use of the low-energy constants c_i and d_i determined from pion-nucleon scattering without any fine tuning. We discuss in detail the construction of the new potentials and convergence of the chiral expansion for two-nucleon observables. We also introduce a new procedure for estimating the theoretical uncertainty from the truncation of the chiral expansion that replaces previous reliance on cutoff variation.
263 citations
TL;DR: Using the covariant spectator theory (CST), the authors presented two one-boson-exchange kernels that have been successfully adjusted to fit the 2007 world$ data (containing 3788 data) below 350 MeV.
Abstract: Using the covariant spectator theory (CST), we present two one-boson-exchange kernels that have been successfully adjusted to fit the 2007 world $\mathit{np}$ data (containing 3788 data) below 350 MeV. One model (which we designate WJC-1) has 27 parameters and fits with a ${\ensuremath{\chi}}^{2}/{N}_{\mathrm{data}}=1.06$. The other model (designated WJC-2) has only 15 parameters and fits with a ${\ensuremath{\chi}}^{2}/{N}_{\mathrm{data}}=1.12$. Both of these models also reproduce the experimental triton binding energy without introducing additional irreducible three-nucleon forces. One result of this work is a new phase-shift analysis, updated for all data until 2006, which is useful even if one does not work within the CST. In carrying out these fits we have reviewed the entire database, adding new data not previously used in other high precision fits and restoring some data omitted in previous fits. A full discussion and evaluation of the 2007 database is presented.
133 citations
TL;DR: In this article, the authors presented a successful fit to neutron-proton and protonproton scattering data below pion production threshold using the delta-shell representation, which includes data within the years 1950 to 2013.
Abstract: Using the delta-shell representation we present a successful fit to neutron-proton and proton-proton scattering data below pion production threshold. A detailed overview of the theory necessary to calculate observables with this potential is presented. A new data selection process is used to obtain the largest mutually consistent data base. The analysis includes data within the years 1950 to 2013. Using 46 parameters we obtain chi^2/Ndata = 1.04 with Ndata = 6713 including normalization data. Phase shifts with error bars are provided.
110 citations
References
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TL;DR: The neutron total cross sections of carbon, aluminium, copper, cadmium and lead have been determined as a function of energy in the range 30 to 139 mev.
Abstract: The neutron total cross sections of carbon, aluminium, copper, cadmium and lead have been determined as a function of energy in the range 30 to 139 mev. The lead total cross section shows a dip at about 60 mev and corresponding dips in the cadmium and copper cross sections appear to occur between 30 and 40 mev. The neutron total cross section of hydrogen has been measured as 56·9±1·8×10-27 cm2 at a neutron energy of 126±2 mev.
39 citations
35 citations
TL;DR: In this article, the authors measured the differential scattering cross section as a function of the scattering angle of the neutrons produced by 350 Mev protons impinging on beryllium.
Abstract: Neutrons produced by 350 Mev protons impinging on beryllium are scattered by hydrogen. We measure the differential scattering cross section as a function of the scattering angle. Results are summarized in Fig. 3 of the paper.
32 citations
TL;DR: In this paper, an attempt has been made to determine satisfactory processing conditions for Ilford G5 electron-sensitive emulsions up to 600 μ in thickness, where the penetration and temperature characteristics of metol-hydroquinone, para-aminophenol, and p-diaminophenol developers have been investigated.
Abstract: Summary An attempt has been made to determine satisfactory processing conditions for Ilford G5 electron-sensitive emulsions up to 600 μ in thickness. The penetration and temperature characteristics of metol-hydroquinone, para-aminophenol, and p-diaminophenol developers have been investigated. The observations show that a p-diaminophenol developer gives satisfactory results and a suitable procedure for processing is described. In addition the problems of fixing, washing and drying, have been studied.
25 citations