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1.
The differential cross section, the vector- and the tensor-analyzing powers of the reaction 2H(d, p)3H have been measured. The polarization data were obtained at 11 energies between 1.0 and 13 MeV at lab angles between 5° and 160°. The data were fitted with Legendre polynomials and the resulting coefficients analyzed for resonances in 4He. Overwhelming evidence for a 1? level at 24.1 MeV and a strong indication of a 4+ level at 24.6 MeV excitation energy have been found.  相似文献   

2.
The 3He spin analysing power of hydrogen (protons) has been measured at a c.m. energy of 20 MeV at 14 c.m. angles from 40° to 160°. The measurement of 3He target polarization was calibrated by measuring the 3He spin analysing power of 4He at an energy and angle where it was ?1.00. The proton-3He differential elastic scattering cross section is also reported at a c.m. energy of 20.0 MeV for 36 c.m. angles from 20° to 170°.  相似文献   

3.
The exclusive 2H( 3He, t)2p reaction has been studied at 2 GeV for energy transfers up to 500 MeV and triton angles up to 3.4°. The protons were measured in the large acceptance magnetic detector DIOGENE, in coincidence with the forward tritons detected in a dedicated magnetic arm. The energy transfer spectra extend well above the pion threshold. However, in the region of Δ excitation, the yield is less than 10% of the inclusive 2H( 3He, t) cross-section, which indicates the small contribution of the ΔN ↦ NN process. The angular distributions of the two protons in their center of mass have been analysed as a function of energy transfer and triton angle and a Legendre polynomial decomposition has been achieved. These data have been compared to a model based on a coupled-channel approach for describing the NN and NΔ systems. Received: 21 October 2002 / Accepted: 15 November 2002 / Published online: 11 March 2003 RID="a" ID="a"e-mail: ramstein@ipno.in2p3.fr RID="†" ID="†"Deceased. RID="†" ID="†"Deceased. RID="d" ID="d"Present adress: School of Engineering, J?nk?ping University, P.O. Box 1026, S-551 11 J?nk?ping, Sweden. Communicated by M. Gar?on  相似文献   

4.
Deuteron spectra from the reaction27Al(n, d)26Mg has been measured at reaction angles 0°→60°, with a spectrometer comprising three multiwire proportional counters followed by a curved plastic scintillator. Spectra were obtained with an energy resolution of ~0.7 MeV and an angle resolution of ~5°. Angular distributions for transitions to the ground state and excited states at 1.81, 2.93 and 4.3 MeV in26Mg were obtained. Distorted waves analysis of the angular distributions yield spectroscopic factors of 0.29(8), 0.9(3), 0.18(7) and 1.9(6) for the ground and excited states, respectively. The results are compared with previous (d,3He) and (n, d) measurements, and with theoretical predictions.  相似文献   

5.
Excitation functions of the 40Ca(d, p)41Ca and 40Ca(d, d)40Ca reactions have been measured at 45°, 90°, 135° and 170° from Ed = 4.50 to 5.43 MeV in 10 keV steps. Angular distributions of these reactions have been taken at Ed = 4.70, 5.00 and 5.30 MeV from 25° to 170° in 5° steps. Transitions were observed to the excited states for the range 0.0 ≦ Ex ≦ 3.74 MeV in 41Ca. Rapid fluctuations in the excitation functions and strong variations of the angular distributions with the incident energy were observed, suggesting that the contribution from compound nucleus processes is very large. Various quantities extracted from the experimental data were compared to the predictions of the statistical theories combined with the DWBA theory for the calculation of the direct reaction amplitudes. The results of the present analysis are consistent with the predictions of the standard statistical theories based on the neglect of the channel-channel correlation.  相似文献   

6.
The 48Ca(3He, d)49Sc reaction has been studied at 25 MeV incident energy. Angular distributions have been measured from 5° to 40° using a split-pole spectrometer, for about 160 levels located up to 18 MeV excitation energy. A local zero-range DWBA analysis has been carried out, using Gamow functions as form factors in the case of unbound states; l-assignments and spectroscopic factors are obtained for a large number of levels, most of them previously unknown. The summed experimental spectroscopic strengths for the T<, l = 1 and l = 3 levels are in good agreement with the shell-model sum-rule limits for 1f-2p proton states, and their energy centroids have been determined. The lg92 strength in 49Sc is strongly fragmented: about 27% of the T< strength is carried by twenty-three levels located between 6.5 and 13.5 MeV. Spectroscopic factors for analog states are compared with those from previous (p, p), (3He, dp) and (d, p) experiments.  相似文献   

7.
本文在Ed=0.1—2.5MeV能量范围内,研究了Be9(d,p0)Be10(0),Be9(d,p1)Be10(3.368MeV),Be9(d,t0)Be8(0),Be9(d,α0)Li7(0)及Be9(d,α1)Li7(0.478MeV)诸反应。在Ed=0.150,0.220,0.401,0.706,1.005,1.301,1.484,1.750,2.000,2.250和2.500MeV共十一个能量上分别测量了这五群出射粒子在θL=10—155°区间的角分布。在θL=135°,Ed=0.1—2.5MeV,在θL=95°,Ed=0.1—2.2MeV,和在θL=112.5°,Ed=0.5—2.5MeV测量了Be9(d,p0)Be10的激发函数。在θL=135°和112.5°,Ed=1.2MeV,用较厚靶(100—300μg/cm2)测量了Be9(d,p0)Be10(0)反应的截面绝对值,结果为σ(p0)L=135°)=1.60mb/sr,σ(p0)L=112.5°)=1.55mb/sr。这样就得到了在此能区内,这五群出射粒子的截面情况。对所得结果进行了一些讨论。  相似文献   

8.
J.F. Clare 《Nuclear Physics A》1973,217(2):342-360
Angular distributions of the polarization of 3He(d, p)4He protons have been measured for unpolarized deuterons with laboratory energies of 1.99, 2.81, 3.94 and 6.00 MeV. The polarizations were determined from the left-right asymmetry of elastic scattering through 60° in 4He gas using a vaned polarimeter whose analyzing power was computed by trajectory tracing from the known p-α polarizations. A contour diagram of proton polarization for deuteron energies of 1 to 12 MeV is presented. A Legendre polynomial expansion of four or five terms has been fitted to the products p(θ)σ(θ). The coefficients of the expansions of these and other measurements show resonance-like behaviour at 5Li excitations of 20.0 and 20.9 MeV. The vector-polarized beam and polarized-target analyzing powers are compared with the proton polarization. The proton polarizations are in good agreement with the 3H(d, n)4He neutron polarizations when compared at the same entrance-channel energy but disagree when compared at equal exit-channel energies or compound-nucleus excitations.  相似文献   

9.
The relative differential cross sections have been measured for the 2H(d, p)3H and the 2H(d, n)3He reactions from 300 keV to 700 keV in 50 keV steps. Angular distributions of all charged particles from the reactions were taken from 20° to 160° in the laboratory system. Energy-dependent asymmetry coefficients from the expansion of the centre-of-mass angular distributions in terms of even powers of cos θ were obtained as were the branching ratios between the two reaction modes. The different energy dependences of the moments of the two cross sections were used to test the need for the existence of a recently reported T = 0 state in 4He.  相似文献   

10.
11.
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   

12.
High-precision measurements of the vector and the three tensor analyzing powers of the mirror reactions 2H(d, p)3H and 2H(d, p)3He are compared between 2.5 and 11.5 MeV incident deuteron energy. Large and complex differences are observed over the whole energy range. Although at the present time proper Coulomb corrections cannot be made, possible charge symmetry violation has to be considered.  相似文献   

13.
The tensor analysing power of the 27Al(d, 3He)26Mg reaction has been measured at Ed = 12.4 MeV. The results are reproduced by predictions of the DWBA including D-state components in the 3He wave function. The magnitude of the tensor analysing power provides information on the asymptotic D-state to S-state ratio in the 3He wave function. The value obtained for 3He is in agreement with the corresponding value for 3H.  相似文献   

14.
The 6Li(p, pd)4He reaction was studied at 200.2 MeV, at the quasi-free angle pair (θp, θd) = (54°, ?48.9°), for noncoplanarity angles φ from 0° to 28°. 6Li αd spectroscopic factors of 0.84 and 0.76 are deduced from our coplanar data at this energy and 120 MeV, respectively, for ground-state 2S Woods-Saxon wave functions. A recent microscopic three-body calculation predicts spectroscopic factors from 0.70 to 0.75; using the ground-state wave functions from this study, we deduce a factor of 0.76 from the 200 MeV data. DWIA calculations fit the measured integrated cross sections versus φ for spectator momenta Pα ? 100 MeV/c at both bombarding energies, but underpredict them for larger Pα. Momentum form factors were better reproduced with 1S αd cluster wave functions for a soft-core bound-state potential than with the 2S Woods-Saxon wave functions, but the former wave functions generate unphysically large (~1.25) spectroscopic factors.  相似文献   

15.
16.
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   

17.
The3He(γ, p)d reaction has been measured in the photon energy region between 200 MeV and 450 MeV at proton c.m. angles between 20° and 150°. Protons and deuterons were detected in coincidence with two time-of-flight spectrometers consisting of scintillation counters; both particles were identified and their energies and angles were measured. The angular distributions show a strong forward peak. The differential cross sections fall off with increasing photon energy without showing a significant influence of theΔ resonance.  相似文献   

18.
The 3H(3He, pα)n reaction has been studied in a kinematically complete experiment at 3He bombarding energies between 0.31 and 2.80 MeV in order to detect a possible resonant energy dependence of the spin singlet (T = 1) neutron-proton final state interaction (FSI). The data in the region of low n-p relative energies have been analyzed in terms of the Watson-Migdal formalism. Only a slight relative increase of the 1S0 n-p FSI is observed with increasing bombarding energy. This result is not easily related to the strong isospin violations found in the two-body reaction 3H(3He, d)4He at similar 3He energies.  相似文献   

19.
The second excited state of8Be has been studied by analysis of the coincidence spectra of the reaction10B(d, α)2α forE d =1.0-2.0 MeV. The excitation energy was found to be 12.0±0.4 MeV, and the reduced width 0.85±0.12 MeV. Differential crosssections of the (d, α 2)-reaction were deduced.  相似文献   

20.
The50Cr(d, n)51Mn and54Fe(d, n)55Co reactions have been studied at an incident deuteron energy of 5.5 MeV. Angular distributions of neutron groups to a number of low-lying levels in the residual nuclei have been recorded. Time-of-flight techniques have been used to record neutron spectra. A liquid scintillator with pulse-shape discrimination property has been used as neutron detector. DWBA calculations have been performed and relative spectroscopic strengths determined for transitions with variousl p values. The ratios between spectroscopic strengths forl p =3 andl p =1 transitions were found to be considerably larger than corresponding ratios obtained from the (3He,d) reactions. Two-step stripping processes competing with the direct stripping process are suggested as explanation of the discrepancy between the (d, n) and the (3He,d) results.  相似文献   

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