The Cr(d, p)Cr reaction and ln = 1 J-dependence in the (d, p) reaction

The ⁵⁰Cr(d, p)⁵¹Cr reaction has been studied at an incident energy of 10 MeV. Spin assignments are made on the basis of empirical rules for the J-dependence of the angular distributions for l_n = 1 and l_n = 3 transitions. Zero-range DWBA calculations are used to extract spectroscopic factors.     

DWBA and CCBA analysis of selected transitions in the C(d,τ) B reaction at Ed = 80 MeV

Angular distribution of the reaction ¹²C(d,τ) ¹¹B leading to the 3/2⁻ ground state and the 4.44 MeV excited (5/2⁻ state ¹¹B have measured at E_d = 80 MeV up to about 70° and 40°, respectively. The inclusion of second-order processes in the framework of CCBA calculations gives a good reproduction of the 3/2⁻ as well as of the DWBA forbidden 3/2⁻ angular distribution. The strong dependence of the cross section on the sign of the deformation supports a positive β₂ value for ¹¹B.     

Investigation of the S(d, p)S reaction at Ed = 10 MeV

Angular distributions of proton groups, corresponding to fifteen levels observed in the reaction ³⁴S(d, p)³⁵S at E_d = 10 MeV have been measured with a split-pole spectrograph equipped with position-sensitive detectors. For the levels at E_x = 0, 1.58, 1.99, 2.34, 2.73, 3.68, 3.80 and 4.20 MeV, l_n = 2, 0, 3, 1, (2, 3), (1), 1 and 1, respectively, has been found from a DWBA analysis. Experimental spectroscopic factors and those following from many-particle shell-model calculations for the lowest four states are in satisfactory agreement. The ground state Q-value has been measured as Q = 4757 ± 5 keV.     

Studies on the Ne(p, d)Ne and Ne(d, p)Ne reactions

Angular distribution measurements have been performed on the ²¹Ne(p, d)²⁰Ne and ²¹Ne(d, p)²²Ne reactions at E_p = 20 MeV and E_d = 10.2 MeV, respectively. In the ²¹Ne(p, d) ²⁰Ne reaction, the prolific formation of the J^π = 2⁺, 1.63 MeV state was characterized by l_n = 2 pickup, and the distribution associated with the 4⁴, 4.25 MeV state was suggestive of a weak l_n = 2 pickup. All of the observed l_n = 1 pickup strength is associated with formation of the 2⁻, 4.97 MeV ²⁰Ne level. The ²¹Ne(d, p)²²Ne results indicate that l_n = 2 transfer is involved in the formation of the 1.28, 3.36, 5.52, 5.63 and 6.65 MeV ²²Ne states. The angular distribution observed for the 2⁺, 4.46 MeV state and also the unresolved 5.33, 5.36 MeV composite of states required both l_n = 0 and l_n = 2 components in the associated distorted-wave Born approximation fits. The spectroscopic factors extracted from the present results are compared with those predicted by the Nilsson model without mixing: Applications of the angular momentum projection rule to the ²¹Ne(d, p)²²Ne reaction are considered.     

Prolate and oblate 10 isomers in Sm78 and Gd78

The N = 78 isotones ¹⁴⁰Sm and ¹⁴²Gd have been studied with -particle- and HI-induced reactions. In both nuclei two close-lying 10⁺ isomers at 3.2 MeV have been established, and from the feeding E2 cascades they are characterized as the prolate and the oblate excitations. A third E2 cascade feeding into the ¹⁴²Gd 8⁺ state is interpreted as the continuation of the collective ground state sequence that might assume the properties of a perfect deformed rotor for spins above 10.     

Simultaneous measurements of the p+d→(A=3)+π reactions

A stack of annular detectors made of high-purity germanium was used to measure simultaneously pd → ³H π⁺ and pd → ³He π⁰ differential cross sections at beam momenta of 750 MeV/c, 800 MeV/c, and 850 MeV/c over a large angular range. The extracted total cross sections for the pd → ³He π⁰ reactions bridge a gap between near threshold data and those in the resonance region. The ratio of the cross sections for the two reaction channels taken at the same η=p^cm_π/m_π yields 2.11±0.08 indicating that a deviation from isospin symmetry is very small.     

Cross-section measurements for the reaction B(p, He)Be

Cross sections have been measured for the transitions to the ground state and first excited state of ⁸Be and to the two 2⁺ levels at 16.63 MeV and 16.93 MeV excitation in the reaction ¹⁰B(p, ³He) at E_p = 49.5 MeV. The angular distributions of the cross section were compared with DWBA predictions.     

The C(Li, t)O reaction at 20 MeV

States in ¹⁶O op to an excitation energy of 16.9 MeV were observed from the ¹³C(⁶Li, t)¹⁶O reaction at 20 MeV. Differential cross sections were obtained from θ_lab = 15° to 105° for the triton groups corresponding to the states in ¹⁶O at 6.13, 6.92, 7.12, 8.87, 9.85, 10.35 and 11.09 MeV.     

The (He, t) reaction at intermediate energies : Spin-isospin multipole transitions

Data for the (³He, t) reaction at 900 MeV and 2 GeV on the targets ²⁶Mg, ⁴⁰Ca, ⁴⁸Ca, ⁵⁴Fe, ⁹⁰Zr and ²⁰⁸Pb are presented. A multipole decomposition for the data at 900 MeV has been made and the different distributions have been analysed. From the L = 0 cross section the Gamow-Teller strength distributions are extracted and compared with (p, n) data. The L = 1 and 2 distributions are analysed in a schematic model which describes the general systematics fairly well. The spectra at 2 GeV and Θ = 4° show for all targets a well-developed quasi-elastic peak. The A-dependence of the cross section is analysed in a simple model.     

Polarization of neutrons from the O(d, n)F reaction

The polarizations of neutrons from the ¹⁶O(d, n₀)¹⁷F and ¹⁶O(d, n₁ ¹⁷F reactions have been measured at 30° (lab) in steps of approximately 0.15 MeV from E_d = 3.96 to 5.35 MeV. Polarization angular distributions have been obtained at 3.96 and 5.35 MeV. It is determined that the random phase approximation for the scattering amplitudes is not appropriate for the compound nucleus contributions. The analysis indicates probable interference between the compound nucleus and direct interaction reaction mechanisms.     

Study of the structure of S and Ar

The ³⁷Cl(d, ³He)³⁶S and ³⁹K(d, ³He)³⁸ Ar reactions have been studied at a bombarding energy of 28.9 MeV. The results are compared with theoretical calculations for two or four holes in the sd-shell. The three-hole spectrum of ³⁷Cl is also briefly discussed. In the calculation for ³⁸Ar, additional states of a two-particle four-hole nature are included. In ³⁸Ar, the ground state and levels at 2.166 and 7.14 MeV are excited principally by l = 2 transfer, while transitions with appreciable l = 0 strength are observed to levels at 3.935, 4.569, 5.158 and 5.563 MeV. This fragmentation is quite well reproduced by the inclusion of the 2p-4h states. In particular the level at 3.935 MeV is largely of this type, a conclusion supported by both the spectroscopic factors and γ transition rates. The ³⁶S ground state and levels at 6.511 and 7.12 MeV in ³⁶S have angular distributions characteristic of l = 2. Three transitions with l = 0 strength are observed to levels at 3.295, 4.523 and 4.577 MeV in this nucleus. An additional level was identified at 7.71 MeV but the l-transfer could not be determined. The data are only qualitatively reproduced by the four-hole calculation, which while useful in making probable J^π assignments, suggests that core excitation is important here also.     

Spectroscopy of C

The ¹⁴C(t, p)¹⁶C reaction locates five new states in ¹⁶C, at excitation energies of 3120 ± 15, 3983 ± 10, 4136 ± 10 and 6109 ± 15 keV, in addition to the g.s. and 1.76 MeV states. The 3.02 and 3.98 MeV states appear to be the second 0⁺ and 2⁺ 2p-2h states, respectively. The 4.14 MeV state has J^π = 4⁺ and the 6.11 MeV state has J^π = 2⁺, 3⁻, or 4⁺.     

The contribution of 2N photon absorption in C(γ,2N) reactions for Eγ = 150–400 MeV

The ¹²C(γ,pn) and ¹²C(γ,pp) reactions have been studied using tagged photons of energy E_γ = 150–400 MeV. Recoil momentum distributions are compared to the results of Monte Carlo calculations based on a two-nucleon photon absorption model and two different phase space models. The ¹²C(γ,pn) data at low missing energy are consistent with absorption on 1p² and 1s1p nucleon pairs.     

Unconventional Medium Effect in K+-and π+-Nucleus Scattering

The ratios of total cross section of K⁺-nucleus to K⁺-deuterium at 400 MeV/c≤pk≤800 MeV/c for ⁶Li, ¹²C, ²⁸Si, ⁴⁰Ca and the differential cross section of π⁺-¹²C scattering at p_π= 800 MeV/c are calculated by taking into account the unconventional medium effect.An enhancement of both the K⁺-and π⁺-nucleus scattering cross sections is obtained.     

95Zr(n,γ)96Zr的间接测量

95Zr（n,γ）96Zr是稳定燃烧的恒星中合成96Zr的唯一途径,对研究恒星演化和重元素合成具有重要的意义。由于95Zr半衰期为64 d,直接测量95Zr（n,γ）96Zr截面极为困难,因此,本工作采用替代比率法间接测量95Zr（n,γ）96Zr截面。本工作测量了94Zr（18O,16Oγ）96Zr和90Zr（18O,16Oγ）92Zr反应,得到了复合核96Zr*和90Zr*衰变到γ道的几率比,并利用截面已知的91Zr（n,γ）92Zr截面乘以实验所测比率,得到了E_n=0~8 MeV能区的95Zr（n,γ）96Zr中子俘获截面。95Zr(n, γ)96Zr cross section is important for the study of stellar evolution and heavy elements nucleosynthesis because the reaction is the only way to produce the 96Zr in Asymptotic giant branch stars. The direct measurement of 95Zr(n, γ)96Zr is very difficult due to the short half-life of 95Zr, 64 days. The surrogate ratio method was carried out to measure 95Zr(n, γ)96Zr cross sections. We measured the 94Zr(18O, 16Oγ)96Zr and 90Zr(18O, 16Oγ)92Zr reactions and obtained the γ-decay probability ratio of compound nuclei 96Zr* and 92Zr*. The 95Zr(n, γ)96Zr cross section is determined by the obtained ratio multiplying the known 91Zr(n, γ)92Zr cross section at E_n=0~8 MeV.     

The (1f7/2) multiplet in Ca

The states of ⁴²Ca below 3.2 MeV excitation are studied by the ⁴¹Ca(d,p)⁴²Ca reaction at 12 MeV bombarding energy. The experimental spectroscopic factors are compared to predictions based on Gerace and Green's coexistence model.     

Cross section of the charged current reaction C(ve, e)Ng.s.

The charged current nuclear transition ¹²C(v_e, e⁻)¹²N_g.s. has been observed in the KARMEN experiment. The flux average cross section for v_e from μ⁺ decay at rest is determined to be σ = [8.1±0.9(stat.)±0.75 (syst.)]×10⁻⁴²cm². For the first time also the energy dependence of the cross section has been measured for neutrino energies up to 50 MeV.     

Polarization of protons from the Be(d, p)Be reaction

The polarization of protons from the ⁹Be(d, p)¹⁰Be reaction has been measured for deuteron energies between 1 and 6 MeV. Angular distributions of the polarization for the ground state proton group (Q=4.59 MeV) have been measured for laboratory angles 10° and 135° at 2.5, 4.0 and 5.5 MeV. The polarization at a laboratory angle of 30° was measured in 0.2 MeV steps between 1 and 6 MeV. In addition the polarization of protons leaving ¹⁰Be in its first excited state (Q=1.22 MeV) was measured between 10° and 90° for a deuteron bombarding energy of 5.5 MeV. Measurements were made by conventional double-scattering techniques using elastic scattering from helium at 45° as the analyser. The results show a strong energy dependence contrary to what one might expect on the basis of the lack of structure in the cross section. The maximum polarization observed at each energy is about 0.35.     

Stopping powers of CR-39 nuclear track material for Z=1−14 ions with 0.25–2.8 MeV/u

Experimental studies of the slowing down of ¹H, ⁴He, ⁷Li, ¹¹B, ¹²C, ¹⁴N, ¹⁶O, ²³Na, ²⁷Al and ²⁸Si ions in CR-39 nuclear track etch material in the ion energy range 0.25–2.8 MeV/u are presented. The ion stopping powers obtained are compared to the predictions of two recent semiempirical models for calculating ion stopping powers. The predictions are found to clearly underestimate the observed stopping powers for ⁷Li, ¹¹B, ¹²C, ²³Na, ²⁷Al and ²⁸Si ions.