A study of the50Cr(d,n)51Mn and54Fe(d,n)55Co reactions

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.     

The88Sr(d,n∼p)88Sr reaction

The⁸⁸Sr(d, n～p)⁸⁸Sr cross section has been measured at 170 ° for deuteron energies from 7.5 to 10.0 MeV, and the total⁸⁸Sr(d, n～p) cross section obtained. The total cross section is compared with results of coupled-channel Born approximation calculations using both empirical and shell-model-reaction-theory form factors to describe the decaying isobaric analog state. It is shown also that the new data and calculations are consistent with earlier⁸⁸Sr(d, p)⁸⁹Sr data.     

Study of the excitation functions of27Al(n, α)24Na,27Al(n,p)27Mg and28Si(n,p)28Al reactions

Cross sections for the reactions²⁷Al(n, p)²⁷Mg and²⁸Si(n,p)²⁸Al were measured by activation method between 13.40 and 14.83 MeV neutron energy. An accuracy of about 4% was achieved using the²⁷Al(n, α)²⁴Na reaction as a reference at 14.1 MeV where the relative excitation function has also been measured. Results obtained were compared to a recent compilation and that calculated by the Hauser-Feshbach model. Using the back-shifted level density formula and taking into account the contribution of the separated levels, the calculations were extended to the energy range from the threshold to 18 MeV. A structure was observed in the²⁷Al(n, α)²⁴Na reaction cross section curve around 14 MeV neutron energy.     

Forward peaking of near Coulomb energy protons in (n,p) reactions at 14.1 MeV

We apply a modified statistical model of compound nucleus reactions to analyse low energy proton angular distributions from the ⁹³Nb(n, p), ^natAg(n, p) and ^natIn(n, p) reactions at E_n=14.1 MeV. The forward peaking at the maximum of the proton evaporation spectrum at E _p = 6–8 MeV is reproduced and interpreted as an indication of the decay of thermalized-nonequilibrated nuclear states.     

A systematic study of (n,d), (n,n' p) and (n,pn) reactions at 14.7 MeV

Cross sections for [(n, d) + (n, n′p) + (n, pn)] reactions induced by 14.7 ± 0.3 MeV neutrons on ⁴⁴Ca, ⁴⁹Ti, ⁵⁰Cr, ^{67, 68}Zn, ⁹²Zr and ^{97, 98}Mo have been measured by the activation technique using enriched isotopes as target materials, modern radiochemical separations and high-resolution counting methods. A brief summary of the literature data and our own earlier measurements is given. Our activation data are generally in agreement with those deduced from emitted charged particle characterisation. Some systematic trends in the activation cross-section data were analysed. Similar to other (n, charged particle) reactions, the [(n, d) + (n, n′p) + (n, pn)] reaction cross section decreases as a function of (N?Z)/A; the data, however, fall on two curves, one for nuclei with neutron separation energies (S_n higher than the proton separation energies (S_p) and the other for nuclei with S_n < S_p. For nuclei with S_n ? S_p the (n, n′p) process is very important. Detailed Hauser-Feshbach calculations show that in general contributions of statistical processes to the (n, d) reaction cross section are very small.     

The RPA nuclear continuum in16O(e,e′) reactions at low momentum transfer decay on (e,e′p) and (e,e′n) reaction channels

A theoretical investigation has been performed of¹⁶O(e, e′) and¹⁶O(e, e′x) reactions at low momentum transfer in the frame of a self-consistent HF and RPA theory with a SK3 interaction. Nuclear responses and their multipole components have been calculated in the whole energy-range for the two electron kinematicsi) ? _i =67 MeV and θ=40°,ii) ? _i =130 MeV and θ=50°. The microscopic structure of HF and RPA resonating states in the energy continuum has been inferred from the calculation. Decay properties in the reaction channels (e, e′p) and (e, e′n) have been discussed in the two cases of a semidirect and a knockout reaction process.     

Be9(d,p),(d,t),(d,a)反应研究

本文在E_d=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E_d=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θ_L=10—155°区间的角分布。在θ_L=135°,E_d=0.1—2.5MeV,在θ_L=95°,E_d=0.1—2.2MeV,和在θ_L=112.5°,E_d=0.5—2.5MeV测量了Be⁹(d,p₀)Be¹⁰的激发函数。在θ_L=135°和112.5°,E_d=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)(θ_L=135°)=1.60mb/sr,σ_(p0)(θ_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。     

Investigation of two resonances in the18O(p,n)18F reaction

Excitation functions for the¹⁸O(p,n)¹⁸F reaction were measured at bombarding energiesE _p=4.6 to 6.6 MeV. In and near two resonances of the yield curves atE _p=5.622 and 6.061 MeV, angular distributions were measured with neutron time-of-flight techniques. The strong neutron decay to theT=1 state in¹⁸F and the similarity of the¹⁸O(p,n) and¹⁸O(n,n) yield curves give good evidence that the structures in the¹⁸O(p,n) yield curve arise from the formation ofT=3/2 states in¹⁹F. A two-level-analysis does not give satisfactory fits to the strongly asymmetric angular distributions.     

Polarisation der Protonen aus der Reaktion10B(d,p 0)11B bei Deuteronenenergien von 1,15, 1,40 und 1,85 MeV

Angular distributions of the polarization of protons from the reaction¹⁰ B(d, p ₀)¹¹ B have been measured between 20 and 148° at deuteron energies of 1.15, 1.40 and 1.85 MeV. Measurements were made by double-scattering techniques using elastic scattering from carbon as the analyser. The results show a strong energy dependence and are in significant accordance with¹⁰ B(d, n ₀)¹¹C data. Calculations have been performed for the mirror reactions¹⁰B(d, p ₀)¹¹B and¹⁰B(d, n ₀)¹¹C in the framework of the Simon and Welton theory assuming two broad compound-states in¹²C, a 2⁺ state at 26.02 MeV and a 3^? state at 26.89 MeV excitation energy.     

Study of the reactions31P(α,p)34S and29Si(α,n)32S

The (α,p) reaction on³¹P in the energy rangeE _α=3.25 to 5.25 MeV and the (α,n) reaction on²⁹Si in the energy rangeE _α=3 to 4.8 MeV, have been used to determine nuclear properties of³⁵Cl and³³S respectively. Resonance energies, strengths and partial widths are reported. The analysis of angular distribution measurements yields spin values for 23 resonance levels in³⁵Cl and 14 levels in³³S.     

The reactions N14(n, α)B11 and N14(n,t)C12 observed with a gridded ionization chamber

The cross sections for the reactions N¹⁴(n, α)B¹¹ and N¹⁴(n, t)C¹² have been measured in the neutron energy range 4.0 to 6.4 MeV and at 2.5 MeV. Mono-energetic neutrons were produced in the D(d, n) He³ reaction using a gas target. The (n, α) and (n, t) disintegrations were detected in a gridded ionization chamber filled with an argonnitrogen mixture. The response of the chamber under different operation conditions is described. The excitation functions, measured with a neutron energy resolution of 40 to 50 keV, are given for theα ₀ group from the N¹⁴(n,α)B¹¹ reaction over the entire neutron energy range and for theα ₁ group and the t₀ group from N¹⁴(n, t) C¹² for neutron energies above 4.3 and 5.6 MeV, respectively.     

The (d,p) Reactions below 3.0 MeV

Excitation functions for a number of proton groups for the reactions ²³Na(d, p)²⁴Na and ²⁷Al(d, p)²⁸Al were measured in the energy range E_d = 1.5 to 3.0 MeV. The angular distributions for a number of proton groups were measured at a number of deuteron energies below 3.0 MeV for the three reactions ¹²C(d, p)¹³C, ²³Na(d, p)²⁴Na and ²⁷Al(d, p)²⁸Al. The theory of deuteron stripping reactions at incident energies below the Coulomb barrier has been considered. A closed analytical form for the differential cross-section has been obtained considering three cases according to the incident deuteron and outgoing proton energies. An attempt has been made to fit the angular distribution measurements at a number of deuterons bombarding energies accordingly.     

Search for a narrow resonance in 6Be with the 4He(3He,n) reaction

The ⁴He(³He, n)⁶Be reaction has been investigated at 36.20 MeV bombarding energy in search for a narrow resonance near the ³He-³He threshold which has been proposed as a possible explanation for the missing solar neutrinos in Davis' experiment. Neutrons have been detected at θ_b = 0° with an effective resolution < 25 keV in the c.m. system, in coincidence with protons emitted at θ_p = 50°. No indication for the existence of such a resonance has been found and an upper limit (dσ/dω)_res ≦ 7.5 μb/sr has been established.     

Bestimmung des Kompoundkern- und Stripping-Anteils der (d,p)- und (d,n)-Reaktionen an Zr94 und Zr96

An experiment has been accomplished which gives information on the reaction mechanism of the (Zr^94,96+d)-reactions. Total cross sections and excitation functions up to 11,8 MeV have been measured for the reactions Zr⁹⁴ (d, p), Zr⁹⁴ (d, n), Zr⁹⁶(d, p), Zr⁹⁶(d, n) and Zr⁹⁶(d, 2n) by the activation method. The results are compared with cross sections calculated according to the statistical theory of nuclear reactions. It is shown that the (d, p) -reactions proceed almost completely by the stripping-mechanism. The (d, n)- and (d, 2n)-excitation functions on the other hand are in good agreement with the predictions of the statistical theory and one can conclude that the compound nucleus mechanism is the dominating process.     

Cross sections of the (n,p) and (n, α) reactions induced in Manganese by 14.7 MeV neutrons

Manganese was irradiated with 14.7 MeV neutrons. By the technique of detecting inducedβ activity in the target material, the σ_n,p+σ_n,σ the reactions induced in⁵⁵Mn has been measured. By detecting inducedγ activity the σ _{n, α} has been measured. Theσ _n,p has been determined from the difference of this two measurements.     

Excitation functions for48Ca(d,p)49Ca(0) in the rangeE d=3.0–5.5 MeV

Excitation curves for⁴⁸Ca(d, p)⁴⁹Ca(0) have been measured at 12 angles in the energy region from 3.0–5.5 MeV with the aim to investigate the charge exchange effect expected at the analogous (d, n) threshold opening at 4.3 MeV. A broad flat minimum is seen in the 165° excitation curve around this threshold which is however much less significant than the charge exchange cusps observed in theA ≈ 90 mass region. More significant structure is seen atE _d≈5 MeV which possibly may be connected with⁴⁸Ca(4.611) core excitation or due to an intermediate state in⁵⁰Sc.     

The (γ, p n) and (γ, 3p3n) reactions in40Ca at intermediate energies

The yields of the reactions⁴⁰Ca(γ, p n)^38g K and⁴⁰Ca(γ, 3p 3n)^34m Cl have been measured by the activation method in the energy range 80–800 MeV. From the measured yields the cross sections are deduced. The experimental cross sections are compared to calculations with a cascade-evaporation model for photo-induced reactions.     

The c(d,n0)n reaction from 3.6 MeV to 12.0 MeV

The excitation function for the reaction ¹²C(d, n₀)¹³N was measured at 0° in the energy range of 3.6 to 12.0 MeV deuteron bombarding energy. Angular distributions were measured at 7.0, 8.0, 9.0, 10.5 and 12.0 MeV deuteron bombarding energies. Cross sections are compared with the ¹²C(d, p₀)¹³C reaction. The yield curves for the neutron and proton groups show a strong similarity in shape. Different sets of deuteron and proton optical-model parameters were used in fitting the 8 MeV energy averaged angular distribution.     

High spin states in73Se observed by the reaction70Ge(α,nγ)

⁷³Se has been investigated by the reaction⁷⁰Ge(α, nγ). Gamma excitation functions (E _α=10–16 MeV), gamma angular distributions (E _α=18 MeV) and gamma-gamma coincidences (E _α=15 MeV)) have been taken. A level scheme has been established, spins and partities have been assigned. States of a rotational band on the 151.2 keV (5/2^?) state and an anomalous band have been identified. Nuclear Reaction⁷⁰Ge(α,nγ)E _α=15 and 18 MeV; measuredE _γ,I _γ,γ-γ-coin.,γ-angular distribution,γ-excitation function.⁷³Se deduced levels,J, π. Enriched target, Ge(Li).