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1.
We have calculated the3He(3He, 2p)4He and3H(3H, 2n)4He reaction cross sections at low energies within the microscopic multichannel resonating group method. For both reactions, we find good agreement with experiment. For the3H(3H, 2n)4He reaction, our calculated energy dependence reproduces that of each individual low-energy experimental data set, except for a normalization constant. Using this fact, we derive at a low-energy3H(3H, 2n)4He rate by taking the averaged mean of these fits.This work has been supported in part by the National Science Foundation, Grants PHY86-04197 and PHY88-17296.  相似文献   

2.
The formalism required to describe the T(d, n)4He or 3He(d, p)4He reaction when all particles may be polarized is discussed. The relation among the various sets of spin-1 tensors is stated explicitly, so that the formulas applying to a particular experiment may be written easily in terms of any desired system.  相似文献   

3.
Possibility of existence of nn ground state was discussed in 2011 by H. Witala and W. Glöckle based on anomalous enhancement of nn QFS (Quasi-Free Scattering) cross section in nd breakup at E n = 26 MeV reported in 2002. To search for the nn ground state, we have made a feasibility study of D(3H,3He)nn and D(n, p)nn experiments. 3H and n secondary beams are produced respectively by D(d,3H)p and D(d, n)3He reactions at forward angle, and are injected on a CD2 foil target. If an nn ground state exists, a single peak is observed in the 3He and p energy spectra. We conclude that these experiments are feasible.  相似文献   

4.
W. Tornow 《Few-Body Systems》2011,50(1-4):443-446
Data are reported for the photodisintegration cross section of the reaction 3He(??, p)2H at ten energies between 7.0 and 16.0?MeV. Very preliminary data are presented for the reaction 4He(??, p)3H between 22.0 and 29.5?MeV in 0.5?MeV energy steps, and for the reaction 4He(??, n)3He at three energies around 28.0?MeV. High-pressure He/Xe gas scintillators served as target and detector. Our data are in better agreement with recent theoretical calculations than the majority of the existing data for all three reactions, but differ significantly from recent data taken with a mono-energetic photon beam and a time-projection chamber.  相似文献   

5.
The differential cross section and the polarization quantities (T11, T20, T21, T22, Pγ') in the deuteron breakup reaction by an α-particle are calculated in the framework of the recently developed three-body model. All values are discussed under the incomplete kinematical condition. All polarization quantities are caused by the difference of the potential between p32 and p12 waves of the N-α interaction. Results of the calculation are compared with the available measurement of (i) the differential cross section and the deuteron vector analysing power in the 4He(d, p)n4He reaction and (ii) the differential cross section and neutron polarization in the 2H(α, n)p4He reaction. The agreement with experiment is very satisfactory in each case. Among the tensor analysing powers of the deuteron the absolute value of T20 is very large. Observables at the FSI peak corresponding to 5Heg.s. are discussed systematically in the energy region of 5.4–20 MeV of the incident deuteron in the 4He(d, p)n4He reaction. Although the differential cross section is not sensitive to the energy of the three-body resonance, the polarization quantities T11, T20, Pγ' are quite sensitive to it.  相似文献   

6.
It is shown that in the angular distributions of the2H(d, p)3H (using polarized and unpolarized deuterons) and likewise in the neutron polarization of the mirror reaction2H(d, n)3He the resonance found atE d ≈105 keV can be understood as a threshold resonance. From the experimental dataJ)π=2(+),T=0 is derived for spin, parity and isospin of the resonance. Additionally it is found, that the resonant part of the reaction has a small coupling matrix element, linking the2H+d channel with the3H+p and3He+n channels.  相似文献   

7.
The neutron-transfer reaction d(6He, p)7He is investigated. The data obtained show that, in the range between 1 and 7 MeV above its ground-state resonance, 7He does not have well-pronounced narrow excited states with a single-particle structure. A resonance state of 5H with an energy of 2 MeV above the n+n+3H decay threshold is obtained for the first time by making use of the reaction p(6He, 2He)5H.  相似文献   

8.
The 2H(d,p)3H and 2H(d,n)3He reactions have been indirectly studied by means of the Trojan Horse Method applied to the quasi-free 2H(3He, p3H)1H?2H(3He, n3He)1H reaction at 18?MeV of beam energy. This is the first experiment where the spectator (here 1H) has been detected in coincidence with the charged participant, avoiding the limitations of standard neutron detectors. The d ? d relative energy has been measured from 1.5?MeV down to 2?keV, at center of mass angles from 40° to 170°. Indirect angular distributions are compared with the direct behaviour in the overlapping regions.  相似文献   

9.
The angular distribution of the photonuclear reaction3He(γ,p)2H was measured with an exitation energyE x=16 to 27 MeV using a 32.5 MeV betatron. In agreement with a theoretical calculation of Böschet al. we found for the coefficients of the distributionf(θ)=b (a/b+sin2θ(1+β·cosθ+γ·cos2θ)) the values:a/b≦0.14; β=0.77 (+0.14; ?0.07); γ≦0.30. This was the first attempt to use spark chambers as a detection device for photonuclear reactions in the low energy range. We found it to be a promising new facility.  相似文献   

10.
Precision measurement of the angular distribution of polarized protons from the2H(d,p)3H reaction at about 1 MeV is compared with experimental polarization data from the mirror reaction2H(d,n)3He at the same entrance and exit channel energies. In both comparisons, differences in polarizations of outgoing nucleons from the d + d charge symmetric reactions were found to be larger than experimental uncertainties.  相似文献   

11.
Using a photon-particle delayed coincidence method the energy distributions of H +H(2p) and H++H(2p) fragment pairs have been measured arising from collisional dissociation of 10 keV H 2 + ions incident on various target gases. H fragments in their 2p state are identified by the Lymanα radiation emitted. The distribution of H+H(2p) fragment pairs arising from dissociative charge exchange reveals a sharp increase below 0.2 eV in the center-of-mass frame of the H 2 + ion. This is ascribed to predissociation of vibrational levels of higher H2 Rydberg states close above then=2 dissociation limit by those H2 Rydberg states which separate into H+H(2p) fragments. Only direct transitions into the continuum of theGK 1 g + state may compete. Some structure at 0.3–0.5 eV is attributed to the three statesI 1 П g,i 3 П g, andh 3 bE g + having potential barriers of this height. The distributions for H++H(2p) have maxima at 3.4, 3.8, and 4.2 eV for a H2, Ar, and He target, respectively, indicating that the 2 u state as well as the 3 g state ofH 2 + is excited. The H+H(2p) process has a greater probability than the H++H(2p) process for Ar and H2 targets, though all electronic H2 states under consideration are bound.  相似文献   

12.
Ab initio calculation of the total cross section for the reactions 4He(γ, p)3H and 4He(γ, n)3He is presented, using state-of-the-art nuclear forces. The Lorentz integral transform (LIT) method is applied, which allows exact treatment of the final state interaction (FSI). The dynamic equations are solved using the effective interaction hyperspherical harmonics method. In this calculation of the cross sections the three-nucleon force is fully taken into account, except in the source term of the LIT equation for the FSI transition matrix element.  相似文献   

13.
The (p, 2p) cross sections on 2H, 3He and 4He were measured at 65, 85 and 100 MeV. The experimental data show rather strong energy and target mass dependence, particularly for 4He.  相似文献   

14.
For deuteron energies below 7 MeV, the evaluation of the differential cross sections of the3H(d,n)4He reaction was improved by including three associated4He particle excitation functions between 4 and 11 MeV. Above 7 MeV, the scale agrees within error limits with that of a previous evaluation, and no energy-dependent systematic deviations between measured and predicted values are observed. However, deviations of up to 20% from the Liskien and Paulsen evaluation are observed.  相似文献   

15.
The left-right asymmetry for the3He(d, p)4He reaction has been measured with a polarized3He target at a bombarding energy of 12 MeV. The experimental results are compared with proton polarization measurements for unpolarized target and beam. The construction of the optically pumped3He target is described. A special design has been chosen to overcome the difficulty that the target contamination caused by the bombarding particles destroys the polarization. The target can easily be purified without removing it from the experimental set-up.  相似文献   

16.
To investigate 5H resonance states with a better instrumental resolution, we utilized the two-neutron transfer reaction 3H(t, p)5H accomplished with the use of a cryogenic liquid-tritium target and 57.5-MeV triton beam. As a result of this study, a valuable fraction of protons detected at ? lab=18°–32° in ptn coincidence events was attributed to the states of the 5H nucleus. Two resonance states situated at 1.8±0.1 and 2.7±0.1 MeV above the t + n + n decay threshold were obtained in the missing mass energy spectrum of the 5H nucleus. The peak located close to E5H was clearly seen in the 5H spectrum obtained from the energy distributions of 3H nuclei emitted in the reaction 2H(6He, 5H)3He at ? lab=17°–32°. The width (Γobs≤0.5 MeV) obtained for the two 5H resonance states is surprisingly small. A state of 4H with E res=3.3 MeV and γ 2=2.3 MeV was obtained in the reaction 2H(t, p)4H from the spectra of protons leaving the target at ? lab=18°–32° and detected in coincidence with neutrons emitted in the decay of 4H nuclei.  相似文献   

17.
New experimental data on the cross sections for the yield of excited 6Li* and 7Li* nuclei and on their contributions to the production of 4He + 2H and 4He+3H light dinuclear systems in 16O p collisions at a momentumof 3.25 A GeV/c per nucleon are presented.  相似文献   

18.
A proper treatment of various electromagnetic contributions toN-4He scattering enables one to determinen(p)-4He observables fromp(n)-4He data. Several calculations ofn-4He observables considering different electromagnetic effects are presented. It is shown that the contribution of thep-4He Coulomb corrections ton-4He polarizations and differential cross sections dominates over other electromagnetic effects forθ c.m.≧30°. For smaller scattering angles, neutron magnetic scattering is important and produces a divergingn-4He differential cross section atθ=0° and a large peak (Mott-Schwinger effect) in the polarization. The influence of thep- andn-4He vacuum polarizations on then-4He observables is found to be small.  相似文献   

19.
We have studied the3H(d, n)4He reaction at low energies within a multi-channel resonating-group calculation based on many-bodyn+ andd+3H configurations and pseudo-states as well as on an effective nucleonnucleon interaction containing central, spin-orbit, and tensor components. The low-energy fusion cross section is excellently reproduced within our approach.Dedicated to Prof. Erich Schmid on the occasion of his 60th birthday  相似文献   

20.
The parametrization of cross-section, polarization, analysing powers, spin-correlation and polarization transfer observables in terms of (l, s, J) matrix elements is given for the3H(d, n)4He reaction at low energies. It is shown that a complete set of matrix elements can be obtained from these observables.  相似文献   

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