Charge Dependence of Nuclear Forces and the Breakup of Deuterons and Tritons

Cerineo, M.; Ilakovac, K.; Šlaus, I.; Tomaš, P.; Valković, V.

doi:10.1103/physrev.133.b948

Cited by 72 publications

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“…This is smaller than the cross section for the breakup H s (n,d)2r?, 3 but is larger than predicted by Gammel and MacKellar. 4 (2) The simultaneous breakup into three neutrons and a proton would give a proton energy spectrum of the form 5 Ep l/2 (E max -Ep) 3 , with E max = 5-1 MeV. The failure to reproduce the experimental data can be interpreted as an indication of strong final interactions and gives hope 8 that the study of the reactions H 3 (rc,/>)3« and He B (p,n)3p might give some information about possible three-body forces.…”

Section: Reactions H 3 (W/>)3w and H 3 (Rc H 4 )Y Atmentioning

confidence: 97%

Information About the Neutron-Neutron Scattering Length from the ReactionH3(n,d)2n

et al. 1965

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Recently the reactions H 2 (7r"~,y)2n and H 2 (w, p)2n were investigated with the aim of determining the neutron-neutron l S 0 scattering length, a nn . The preferred value for a nn extracted from the first reaction is 1 ' 2 -17 F, unfortunately with an uncertainty of about 5 F. Several investigations 3 " 5 of the second reaction gave values around -22 F. While the theoretical analysis of the reaction H 2 (7T~,y)2« can be performed with an accuracy of ±1 F, 8 the reactions with more than two nucleons in the final state are considerably more difficult for interpretation.In a reaction a+A-~b +n + n the spectrum of the particle b reflects the neutron-neutron final-state interaction. However, distortive effects arise from at least two sources 7 :(i) Interaction between b and the system 2w. It is reasonable to expect that this depends upon the type of the particle b and on the relative b-2n energy.(ii) The interference between the n-n and the n-b resonances 8 and the interference between resonant and nonresonant processes. 9 The study of the reaction H 3 (n,d)2n offers another possibility 4 to extract a nn . The comparison of the reaction E 2 (n f p)2n and E B (n,d)2n allows one also to investigate the influence of the various distortive effects.In order to determine kinematically such a reaction one has to measure five parameters. The measurement of the energy of the charged particle at 0° at a fixed incident energy is, thus, an incomplete measurement, and only that region of the spectrum which corresponds to the strong final-state interaction of the two neutrons is liable to meaningful interpretation.The deuteron spectra from the reaction H 3 (n, d)2n at E n = 14.4 MeV were measured with different detecting systems. The targets used were (1) a solid Cu-Ti-H 3 target containing 0.3 mg of H 3 and 10% of He 3 ; (2) two gas targets, one containing 0.1 mg and the other 1.3 mg of H 3 , with the He 3 content less than 0.4%. The charged particles were detected with a semiconductor counter telescope 10 in conjunction with multidimensional analyzers. 11 The telescope consisted of two thin AE counters and an E counter depleted to detect 11.5-MeV protons.Two pulses (from the A£ 2 and E counters) were analyzed by a lOOxlOO-channel analyzer. The resulting three-dimensional graphs gave proton, deuteron, and triton &E 2 -vs-E spectra simultaneously. 12 In a set of measurements three pulses (from the AE lf &E 29 and E counters) were analyzed by a lOOxlOOxlOO-channel analyzer. All those events for which AE X and AE 2 pulses did not satisfy specific criteria were rejected. 13

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Section: Reactions H 3 (W/>)3w and H 3 (Rc H 4 )Y Atmentioning

confidence: 97%

Information About the Neutron-Neutron Scattering Length from the ReactionH3(n,d)2n

et al. 1965

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“…All the terms independent of the energy of the third particle are included in g (6), which is fixed experimentally by normalizing the theoretical prediction to the experimental data. effective range for the p-p interaction, taken as 2.65 F in our analyses.…”

Section: C(ri)p(ej Chr 1 )E 2p + (Nym P )[-L/a P -H(r } )/R+y P E 2p ]mentioning

confidence: 99%

Two-Proton Final-State Interactions in the ReactionsD(He3, t)2p
Morton
¹
,
Gross
²
,
Malanify
³

et al. 1967
Phys. Rev. Lett.
12
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the static prolate minimum by several tens of MeV and immediate fission should result.For collisions below the barrier these distortion effects are closely related to Coulomb excitation theory, but we have not developed the correspondence. It should be mentioned in this connection that the Geilikman interaction includes moderately large terms which are neglected in the usual multipole expansion of the trajectory and that the large classical oscillation amplitudes which we find imply that high-order perturbation theory is needed. In any case, it is indicated that strong vibrational excitation will be observed in collisions of heavy ions.I wish to thank G. Breit, G. T. Garvey, and J. Weneser for conversations on this work and J. Vitale for programming the integrations.Final-state interactions of two nucleons continue to be of interest, particularly from the point of view of determining the 1 S 0 scattering length for two neutrons, a n . Recently 1 the 3 He spectra at 6 and 8° (lab) from the reaction T(d, 3 He)2n were analyzed using the final-state interaction theory of Watson 2 and Migdal 3 and gave a value of#^ = -16.1±1.0 F. Application of the simple Watson-Migdal theory was justified by analysis of the triton spectrum at 8° (lab) from the reaction 3 He(d,t)2p for the same cm. energy. Using the same theory a value of ap = -7.41"to;49 F was found, 1 which agrees with the results of low energy free p-p scattering. The scattering length a n from this experiment agrees with the result of the D(7r~, y)2n experiment 4 where a n = -16.4± 1.3 F, and also agrees with the theoretical prediction of Heller, Signell, and Yoder 5 based on charge symmetry of nuclear forces and the experimental value for ap. In disagreement with the above results, . similar analyses 6 ? 7 of the proton spectra from the reaction ~D(n,p)2n for an incident neutron energy of 14 MeV gave a n = -21 ± 2 F, and -23.6+^6 F. The final-state interaction of two protons has also been observed 8 in the reaction 3 H.e(p,d)2p for 12-MeV incident protons. However, the high-energy peak was found to be much narrower than the prediction of the Watson-Migdaltheory.The final-state interaction theory as formulated by Watson and Migdal does not include the details of the reaction mechanism other than that the interaction be of short range. As a test of the applicability of this theory we report here results for the reactions D( 3 He, t)2p and 3 Ee(d,t)2pinvolving two protons in the final state. Experimental conditions were chosen so that the tritons correspond to 0 and -180° emission from the same initial reaction: 3 He +d at 21 MeV cm. energy. The two final states presumably result from different reaction mech- TWO-PROTON FINAL-STATE INTERACTIONS IN THE REACTIONS D(Triton spectra were measured at 0 and 3° for the reaction D( z Ke,t)2p and at 5° for the reaction 3 H.e (d,t)2p at the same cm. energy (21 MeV). The results were compared with predictions of the Watson-Migdal final-state interaction theory, and the proton-proton scattering length ap was determined for each ...

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“…Phillips and Crowe 7 have measured the y-ray spectrum from this reaction and obtained a value for a of -15.9 F with probable errors of -<*> F and +7.4 F. A recent measurement by Cerineo et al 8 of the proton spectrum from the d(n,p)2n reaction yields a value for a of -21.7 ± 1 F. Although the statistical accuracy of this latter experiment is quite good, there seems to be considerable uncertainty in the assumptions used in the theoretical analysis.…”

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“…Cerineo et al 8 have compared their measured value for a with that predicted by two different theoretical approaches. When compared with the predictions made by Lin, 5 a 2 to 3% difference in the coupling constants between the 77° meson and the proton and neutron, respectively, is required to achieve agreement between the calculation and the measurement.…”

mentioning

confidence: 97%

Measurement of thennSingletS-State Scattering Length

Ryan

1964

Phys. Rev. Lett.

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A measurement is reported of the spectrum of y rays from the reaction iT+d^n+n+y (1) for r\~ mesons stopped in liquid deuterium. A 180-deg-focusing y-ray pair spectrometer 1 with an energy resolution of 1% was used as the detector. The measured spectrum was compared with theoretical spectra yielding a value for the neutron-neutron singlet S-state scattering length a. It is well known from existing experimental results that for the nucleon-nucleon interaction the np and pp singlet state scattering lengths differ considerably. The apparent violation of charge independence has stimulated considerable work in attempts at a reasonable explanation. 2-6 One of the desirable pieces of information to help clarify the situation is the nn scattering length.One of the cleanest ways of measuring a is by means of Reaction (1), since in the final state only the two neutrons interact strongly. Phillips and Crowe 7 have measured the y-ray spectrum from this reaction and obtained a value for a of -15.9 F with probable errors of -<*> F and +7.4 F. A recent measurement by Cerineo et al. 8 of the proton spectrum from the d(n,p)2n reaction yields a value for a of -21.7 ± 1 F. Although the statistical accuracy of this latter experiment is quite good, there seems to be considerable uncertainty in the assumptions used in the theoretical analysis.A detailed description of the experimental setup for the present measurement is given in reference 1. 7r~ mesons from the Berkeley 184-in. synchrocyclotron were stopped in liquid hydrogen and also in liquid deuterium. The spectrum of y rays from the radiative reaction in hydrogen, 77 +p-~n+y,and Reaction (1) in deuterium were both measured. Identical spectrometer settings were employed for the two measurements. The measured deuterium spectrum was compared with theory in a manner identical to that employed by Phillips and Crowe. 7 In this analysis the energy resolution function for the spectrometer is folded into theoretical spectra evaluated for different values of the nn scattering length. The scattering length is then determined by the best fit of the measured spectrum with the folded theoretical spectra.A theoretical calculation of the spectra has been made by Watson and Stuart 9 who employ the impulse approximation and consider the two finalstate neutrons to interact only in the singlet S state. The nn wave function is approximated by a square well with the correct scattering length and effective range r 0 . For the deuteron S state the Hulthe'n wave function (e~a r -e~@ r )/r is employed. The validity of the approximations made in the calculation are discussed by Watson and Stuart and also by McVoy. 10 Calculations made by McVoy of the integrals which occur in the formula for the spectra were used by us in the numerical calculation. An IBM 7074 computer was employed. For this calculation the following constants were used: r 0 = 2.65 F, /x = 139.58 MeV, M W /JLL = 6.7310, a/\i = 0.3274, /3/JLL = 1.54, [M ~(M n -Mp) -Bo]/M n = 0.9141 /x. Here, /x is the TTmeson mass, M n the neutron mass, Mp...

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Charge Dependence of Nuclear Forces and the Breakup of Deuterons and Tritons

Cited by 72 publications

References 50 publications

Information About the Neutron-Neutron Scattering Length from the ReactionH3(n,d)2n

Information About the Neutron-Neutron Scattering Length from the ReactionH3(n,d)2n

Two-Proton Final-State Interactions in the ReactionsD(He3, t)2p
Morton
¹
,
Gross
²
,
Malanify
³

et al. 1967
Phys. Rev. Lett.
12
0
1
0
View full text Add to dashboard Cite

Measurement of thennSingletS-State Scattering Length

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Charge Dependence of Nuclear Forces and the Breakup of Deuterons and Tritons

Cited by 72 publications

References 50 publications

Information About the Neutron-Neutron Scattering Length from the ReactionH3(n,d)2n

Information About the Neutron-Neutron Scattering Length from the ReactionH3(n,d)2n

Two-Proton Final-State Interactions in the ReactionsD(He3, t)2pMorton1, Gross2, Malanify3 et al. 1967Phys. Rev. Lett.12010View full textAdd to dashboardCite

Measurement of thennSingletS-State Scattering Length

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Two-Proton Final-State Interactions in the ReactionsD(He3, t)2p
Morton
¹
,
Gross
²
,
Malanify
³

et al. 1967
Phys. Rev. Lett.
12
0
1
0
View full text Add to dashboard Cite