The Isobaric-Analogue Resonance States in the Fe56 Nucleus

Gamma ray spectra from the reaction Mn⁵⁵(p, γ) Fe^56ß have been measured at the isobaric-analogue resonances at E_p = 1769 ± 4 keV and 1806 ± 4 keV respectively with a 15 cm³ Ge(Li) dedector. Double correlation for the transition from the resonance level to the second excited state of Fe⁵⁶ has been measured for the two cases. Proton elastic scattering was also studied at each resonance at the angle 150°. Analysis of the (p, y) and (p, p) works yields a J^π assignment 4⁺ or 5⁺ and 3⁺ for the two mentioned resonance states, respectively, which are the isobaric-analogues of the 0.454 MeV and 0.486 MeV states of Mn⁵⁶. The proton partial width and the total width for each resonance state were also determined.     

Isobaric Analogue State of the 341 KeV Level of Mn56 and Fe56

When Mn⁵⁵ is bombarded by protons, a proton capture resonance is detected at E_p = (1678 ± 4) KeV. The spectral and angular distribution studies of the (p, γ) and (p, p) reactions at this resonance have established J^π = 3⁺, l_p, = 1, Γ_p = (1 = 0.2) KeV and Γ = 17 KeV for the energy level at (11836 ± 4) KeV in the Fe⁵⁶ nucleus. Comparison of the present results with those obtained by (n, γ) and (d, p) reactions on the Mn⁵⁵ nucleus suggests that this resonance state is most probably the isobaric analogue of one member of the doublet at 341 KeV in the Mn⁵⁶ nucleus.     

Anomalies in Elastic Scattering at Isobaric Analogue States

Excitation functions for proton elastic scattering on Mn⁵⁵ at proton energies from 1320 KeV to 1480 KeV have been measured at the angles 135° and 150°. Anomalies in the differential elastic scattering were observed at E_p = 1350 ± 4 KeV, 1385 ± 4 KeV and 1445 ± 4 KeV respectively. These resonance states are the isobaric analogues of the ground, first excited and second excited states in Mn⁵⁶ respectively. Analysis of the results showed that these resonance states are best fitted to a J^π = 3⁺, 2⁺ and 1⁺ which is in excellent agreement with the J^π values of the corresponding states in Mn⁵⁶. The total widths and proton widths of these states were determined.     

Derp 3/2-Analogzustand in51V

In an investigation ofT=7/2 analogue states in⁵¹V the⁵⁰Ti(p, γ) excitation curve has been measured for proton bombarding energies 1280–1480 keV and 2340–2660 keV. From the (p, γ) resonances 29 new virtual levels in the region of 9316–9510 keV excitation energy in⁵¹V were determined. The strong resonance atE _p=1 371 keV has been identified as the isobaric analogue state of the⁵¹Ti ground state by determining spin and parity of this resonance to be 3/2^?. There is no evidence for a strong analogue resonance in⁵¹V corresponding to the 1.16 MeV _{p 1/2} state in⁵¹Ti. The γ-decay of the _{p 3/2} analogue state has been studied by measuring branching ratios and angular distributions of primary γ-transitions with a Ge(Li) detector.M1E2 mixing ratios have been determined for these transitions. The total width of the resonance for γ-decay is found to be Γ_γ=1.6±0.4 eV. New bound levels in⁵¹V have been introduced at 3576, 4651 and 4661 keV excitation energy. TheJ ^π values of the 3085, 4770, and 4863 keV states are determined to be 5/2^?, 5/2^?, 3/2^?, respectively. The analogue-antianalogueM1 transition strength is found to be considerably reduced compared to the situation ins-d shell nuclei.     

Alpha decay of isobaric analogue states in24Mg and28Si

Theα-decay of isobaric analogue states (which are forbidden by isospin selection rules) excited in²⁴Mg and²⁸Si through preton capture by²³Na atE _p=677 and 739 keV and by²⁷Al atE _p=295, 327 and 405 keV, respectively, have been studied using solid state track detectors. The ratio ofα-decay widths of the two resonance states in²⁴Mg to the state at 1.632 MeV (2⁺) in²⁰Ne yields the value 0.065 for the mixing parameterε and the value 4.01 keV for the Coulomb matrix element responsible for the isospin mixing in²⁴Mg. In²⁸Si the measurement of theα-decay widths of the three resonance states resulted in the determination of the proton, gamma and alpha partial widths which comprise the total width of the resonance states. Limits have been set for the value of the two mixing parameters involved in this case. Upper limits of 16 and 39 keV have been obtained for the Coulomb matrix elements responsible for the isospin mixing in²⁸Si.     

Widths of the 7.74 MeV analogue state in39K

The³⁸Ar(p, p)³⁸Ar and³⁸Ar(p, γ)³⁹K reactions have been investigated in the analogue resonance region at E_p=1.39 MeV. For the 7.74 MeV state of³⁹K branching ratios, unique spin and parity, \(J^\pi = \tfrac{3}{2} - \) , proton and total width, Γ_p=Γ=1.1±0.2 keV, have been determined.     

Total (p,n) reaction cross section study on51V over the incident energy range 1·56 to 5·53 MeV

The total (p, n) reaction cross section for⁵¹V has been measured as a function of proton energy in the energy range 1·56 to 5·53 MeV with thick and thin targets. The fluctuations in the fine resolution excitation functions were analysed, to extract 〈Γ〉, the coherence width. The thick target excitation function suitably averaged over appropriate energy intervals has been compared with the optical model, Hauser-Feshbach and Hauser-Feshbach-Moldauer calculations. The strong isobaric analog resonance atE _p ～ 2·340 has been shape analysed to extract the proton width Γ _p , the spreading withW and the spectroscopic factor.     

High resolution gamma-ray spectroscopy of the27Al(p,γ)28Si resonance reaction

High resolution gamma-ray spectra have been measured from the²⁷Al (p,γ)²⁸Si reaction for the resonances atE _p=2·482, 2·511 and 2·735 MeV at ϑ _pγ=0°, 30°, 55° and 90° using a Ge (Li) gamma spectrometer. From the spectra and the angular distributions the properties of the resonance states have been obtained. These states are the isobaric analogues of the levels at 4·69, 4·75 and 4·93MeV levels respectively in the parent nucleus A²⁸l.     

Reaction48Ca (p,n)48Sc fromE p =1.885 to 5.1 MeV

The total (p, n) reaction cross section for⁴⁸Ca has been measured as a function of proton energy in the energy range 1.885 to 5.100 MeV with an overall resolution of ∼ 2 keV and in ∼ 5 keV energy steps. The fluctutions in fine resolution data have been analysed to determine the average coherence width 〈Γ〉. The excitation function averaged over large energy intervals has been analyzed in terms of the optical model. The isobaric analogue resonances atE _p ∼ 1.95 and 4 MeV have been shape-analyzed to extract the proton partial width and the spectroscopic factorS _n . A comparison of the gross structures observed in ∼ 55 keV averaged excitation function with the predictions of Izumo’s partial equilibrium model has also been made.     

Line shape and excitation strength of the first excited state in9Be

The line shape and the excitation strength of the very weak first excited J ^π =1/2⁺ state at E_x=1.684 MeV in Zeitschrift für Physik Zeitschrift für Physik⁹Be has been investigated with high-resolution inelastic electron scattering at E₀=45 and 49 MeV and scattering angles θ=105°, 117°, 129° and 165°, and with high-resolution inelastic proton scattering at E₀=13MeV and θ=15° and 18°. Due to lying just above the neutron threshold the level has a strongly asymmetric line shape which in both experiments can be described consistently with a Breit-Wigner expression modified on the low energy side by the threshold behaviour of the cross section. The resonance energy is E_R=1.684 ± 0.007 MeV and the width T=217± 10 keV in thec.m. system. A single particle potential model calculation reproduces the line shape and the resonance parameters fairly well. In addition, the inelastic electron scattering form factor has been measured. In the range of momentum transfersq =0.24-0.46 fm^?1 it is dominated by a 0p_3/2→ 1s_1/2 particle-hole transition. The transition is mainly longitudinal and of isoscalar nature with a strength of B (E1)↑ =0.027 + 0.002 e² fm², but a small M2 contribution ofB(M2)↑=8.8 ±1.5 μ _N ² fm² has also been detected.     

A new determination of the partial widths of the 16.11 MeV state in 12C

The partial widths of the second T = 1 state of ¹²C, at 16.11 MeV excitation energy, have been determined by measuring the ¹¹B(p, γ) and ¹¹B(p, α) cross sections at the E_p = 163 keV resonance corresponding to this state. These measurements result in the new values of Γ_p = 21.7 ± 1.8 eV and Γ_γ = 21.6 ± 3.3 eV, for the partial widths of this state; approximately 3 times smaller and larger, respectively, than the present values in the literature. The new result for the proton width eliminates a serious discrepancy found in an earlier comparison of the partial widths of the T = 1 analogue states of the A = 12 system. Measurements were also made of the ¹¹B(d, n)¹²C¹ reaction to compare the proton widths of the 15.11 and 16.11 MeV T = 1 states; these measurements confirm the new, smaller proton width for the 16.11 MeV state. An attempt was also made to determine the γ-width of the 16.11 MeV state by measuring the γ-branching ratio in the ¹⁰B(³He, p)¹²C¹(γ)¹²C reaction.     

Mass measurements of 19Na and 23Al using the (3He, 8Li) reaction

The mass excesses of ¹⁹Na and ²³Al have been measured with the (³He, ⁸Li) reaction. The values obtained are 12928 ± 12 keV and 6767 ± 25 keV, respectively. The first excited state of ¹⁹Na, observed to lie at 120 ± 10 keV, completes a mass quartet which agrees with a quadratic isobaric multiplet mass equation.     

Nuclear larmor precession of the 14 keV state of57Fe in α-iron following the reaction56Fe (d,p)57Fe

The spin precession of the 14 keV state of⁵⁷Fe, excited by the⁵⁶Fe(d,p) reaction was observed in ferromagnetic Fe. The data yield a magnetic field of ? 330±4 kG and a relaxation time τ _r > 500 ns at room temperature.     

Q-value for the Fermi beta-decay of <Superscript>46</Superscript>V

By comparing the Q -values for the ⁴⁶Ti ( ³He , t ⁴⁶V and ⁴⁷Ti ( ³He , t ⁴⁷V reactions to the isobaric analogue states the Q -value for the superallowed Fermi decay of ⁴⁶V has been determined as Q _EC( ^46V ) = (7052.11±0.27) keV. The result is compatible with the values from two recent direct mass measurements but is at variance with the previously most precise reaction Q -value. As additional input quantity we have determined the neutron separation energy S _n( ^47Ti ) = (8880.51±0.25) keV.     

Total strength of the magnetic dipole resonance in <Superscript>31</Superscript>P

The γ decay of the resonance-like structure observed in the ³⁰Si(pγ)³¹P reaction in the energy range E _p = 1.4–2.7 MeV of accelerated protons has been investigated. The excitation function of this reaction and the spectra and angular distributions of the γ rays formed in the decay of resonances with E _p = 1482, 2350, and 2505 keV have been measured. The M1 resonance on the ground and the first excited states of ³¹P with E _p = 1266 keV is identified. The total strength of the M1 resonance on the ground state of this nucleus is determined. The position and total strength of this resonance on the ground state are explained taking into account pairing forces.     

Investigation of the reaction 34S(p, γ)35Cl: (I). Resonances at proton energies above 2 MeV

The yield curve of the reaction ³⁴S(p, γ)³⁵Cl has been measured over the energy range E_p = 1.95–2.91 MeV. Proton energies and strengths of 84 resonances are given. The decay schemes of 38 selected resonances have been studied, and for these branching ratios and spin limits are presented. The proton energy of the well known $\text{J}{}^{\mathrm{\pi }}\text{=}\text{7}\text{2}{}^{\mathrm{?}}$ analogue resonance has been measured as E_p = 1211.45 ± 0.09 keV. The reaction Q-value is Q = 6371.6 ± 0.4 keV.     

Observation of a narrow resonance formed in e+e− annihilation at 9.46 GeV

An experiment using the PLUTO detector has observed the formation of a narrow, high mass, resonance in e⁺e^? annihilations at the DORIS storage ring. The mass is determined to be 9.46±0.01 GeV which is consistent with that of the Upsilon. The gaussian width σ is observed as 8±1 MeV and is equal to the DORIS energy resolution. This suggests that the resonance is a bound state of a new heavy quark-antiquark pair. An electronic width Γ_ee=1.3±0.4 keV was obtained. In standard theoretical models, this favors a quark charge assignment of $\text{1}\text{3}$.     

Long-range alpha emission inP-wave neutron induced fission of235U

The yield and energy distribution of long-range alpha-particles (lra) emitted from neutron-induced fission of²³⁵U have been measured at neutron energies; thermal, 125±12, 155±11, 185±10, 210±9, 240±9, 365±50 and 480±45 keV. The long-range alpha-particles were detected in cellulose nitrate track detector foils. Results showed an increase of about 50% in the yield at neutron energies in the region 150 keV≤E _n≤220 keV as compared to that of thermal neutrons. A calculation has been carried out to extract thelra to binary fission ratio forp-wave neutron induced fission.     

High-resolution resonance study of the12C+n total cross section in the region of13CT=3/2 states

The¹²C+n total cross section has been studied in the region of the lowestT=3/2 states of¹³C. The firstT=3/2 state at (15108.2±1.2) keV excitation is observed as a weak resonance anomaly. The deduced resonance parameters agree with previous results. At higher excitation energies four sharp anomalies have been observed at (17534±3) keV, (18082±3) keV, (20057±4) keV and (21703±4) keV excitation with total widths between 12 keV and 20 keV. The results are discussed with respect to a possibleT=3/2 assignment. An upper limit of the elasticity (J+1/2) Γ_no/gG is deduced for thoseT=3/2 levels which do not appear as resonance anomalies.     

Resonance strength measurements in the 24Mg(p, γ) 25Al reaction

The strength ωγ of the E_p = 823 keV resonance in ²⁴Mg(p, γ) ²⁵Al was determined to be ωγ = 490 ± 70 me V, by comparison with the Rutherford cross section measured in the energy region of E_p = 600–800 keV. The strength of other low-lying resonances at E_p = 224, 419, 1483, 1623, 1654 and 2010 keV were determined relative to this new value.