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Register a new userNew measurement of the excited states in $^{11}$B via the elastic resonance scattering of $^{10}$Be + p
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The elastic resonance scattering protons decayed from $^{11}$B to the ground state of $^{10}$Be were measured using the thick-target technique in inverse kinematics at the Heavy Ion Research Facility in Lanzhou (HIRFL). The obtained excitation functions were well described by a multichannel R-matrix procedure under the kinematics process assumption of resonant elastic scattering. The excitation energy of the resonant states ranges from 13.0 to 17.0 MeV, and their resonant parameters such as the resonant energy E$_{x}$, the spin-parity J$^pi$, and the proton-decay partial width $Gamma_p$ were determined from R-matrix fits to the data. Two of these states around E$_{x}$ = 14.55 MeV [J$^pi$ = (3/2$^+$, 5/2$^+$), $Gamma_p$ = 475 $pm$ 80 keV] and E$_{x}$ = 14.74 MeV [J$^pi$ = 3/2$^-$, $Gamma_p$ = 830 $pm$ 145 keV], and a probably populated state at E$_x$ = 16.18 MeV [J$^pi$ =(1/2$^-$, 3/2$^-$), $Gamma_p$ $<$ 60 keV], are respectively assigned to the well-known states in $^{11}$B at 14.34 MeV, 15.29 MeV, and 16.43 MeV. The isospin of these three states were previously determined to be T = 3/2, but discrepancies exist in widths and energies due to the current counting statistics and energy resolution. We have compared these states with previous measurements, and the observation of the possibly populated resonance is discussed.
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The $^{10}$B(p,$alpha_0$)$^7$Be bare nucleus astrophysical S(E)-factor has been measured for the first time at energies from about 100 keV down to about 5 keV by means of the Trojan Horse Method (THM). In this energy region, the S(E)-factor is strongly dominated by the 8.699 MeV $^{11}$C level (J$^{pi}$=$frac{5}{2}$$^+$), producing an s-wave resonance centered at about 10 keV in the entrance channel. Up to now, only the high energy tail of this resonant has been measured, while the low-energy trend is extrapolated from the available direct data. The THM has been applied to the quasi-free $^2$H($^{10}$B,$alpha_0$$^7$Be)n reaction induced at a boron-beam energy of 24.5 MeV. An accurate analysis brings to the determination of the $^{10}$B(p,$alpha_0$)$^7$Be S(E)-factor and of the corresponding electron screening potential $U_e$, thus giving for the first time an independent evaluation of it.
Background The nuclear structure of the cluster bands in $^{20}$Ne presents a challenge for different theoretical approaches. It is especially difficult to explain the broad 0$^+$, 2$^+$ states at 9 MeV excitation energy. Simultaneously, it is important to obtain more reliable experimental data for these levels in order to quantitatively assess the theoretical framework. Purpose To obtain new data on $^{20}$Ne $alpha$ cluster structure. Method Thick target inverse kinematics technique was used to study the $^{16}$O+$alpha$ resonance elastic scattering and the data were analyzed using an textit{R} matrix approach. The $^{20}$Ne spectrum, the cluster and nucleon spectroscopic factors were calculated using cluster-nucleon configuration interaction model (CNCIM). Results We determined the parameters of the broad resonances in textsuperscript{20}Ne: 0$^+$ level at 8.77 $pm$ 0.150 MeV with a width of 750 (+500/-220) keV; 2$^+$ level at 8.75 $pm$ 0.100 MeV with the width of 695 $pm$ 120 keV; the width of 9.48 MeV level of 65 $pm$ 20 keV and showed that 9.19 MeV, 2$^+$ level (if exists) should have width $leq$ 10 keV. The detailed comparison of the theoretical CNCIM predictions with the experimental data on cluster states was made. Conclusions Our experimental results by the TTIK method generally confirm the adopted data on $alpha$ cluster levels in $^{20}$Ne. The CNCIM gives a good description of the $^{20}$Ne positive parity states up to an excitation energy of $sim$ 7 MeV, predicting reasonably well the excitation energy of the states and their cluster and single particle properties. At higher excitations, the qualitative disagreement with the experimentally observed structure is evident, especially for broad resonances.
In this article a method for lifetime measurements in the sub-picosecond regime via the Doppler-shift attenuation method (DSAM) following the inelastic proton scattering reaction is presented. In a pioneering experiment we extracted the lifetimes of 30 excited low-spin states of $^{96}$Ru, taking advantage of the coincident detection of scattered protons and de-exciting $gamma$-rays as well as the large number of particle and $gamma$-ray detectors provided by the SONIC@HORUS setup at the University of Cologne. The large amount of new experimental data shows that this technique is suited for the measurement of lifetimes of excited low-spin states, especially for isotopes with a low isotopic abundance, where $(n,n^{prime}gamma$) or - in case of investigating dipole excitations - ($gamma,gamma^{prime}$) experiments are not feasible due to the lack of sufficient isotopically enriched target material.
How does nature hold together protons and neutrons to form the wide variety of complex nuclei in the universe? Describing many-nucleon systems from the fundamental theory of quantum chromodynamics has been the greatest challenge in answering this question. The chiral effective field theory description of the nuclear force now makes this possible but requires certain parameters that are not uniquely determined. Defining the nuclear force needs identification of observables sensitive to the different parametrizations. From a measurement of proton elastic scattering on $^{10}$C at TRIUMF and ab initio nuclear reaction calculations we show that the shape and magnitude of the measured differential cross section is strongly sensitive to the nuclear force prescription.
The analyzing powers in proton-deuteron elastic and proton-neutron quasi-elastic scattering have been measured at small angles using a polarized proton beam at the COSY storage ring incident on an unpolarized deuterium target. The data were taken at 796MeV and five higher energies from 1600MeV to 2400MeV. The analyzing power in pd elastic scattering was studied by detecting the low energy recoil deuteron in telescopes placed symmetrically in the COSY plane to the left and right of the beam whereas for pn quasi-elastic scattering a low energy proton was registered in one of the telescopes in coincidence with a fast scattered proton measured in the ANKE magnetic spectrometer. Though the experiment explores new domains, the results are consistent with the limited published information.
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