Thick Target Inverse Kinematics Method Research Articles

Novel thick-target inverse kinematics method for the astrophysical 12C+12C fusion reaction

Novel thick-target inverse kinematics method for the astrophysical 12C+12C fusion reaction

Resonant scattering measurement for 11C using thick target in inverse kinematics

The resonant scattering of 10B+p reaction was measured at θ c.m.= 180°, 170°, 160°, 150° and 140° using a 35.93 MeV 10B beam to investigate the spectroscopy of 11C with the thick target inverse kinematic method at RIBRAS facility, IFUSP, São Paulo. Influence of the stopping power uncertainty on the resonant scattering cross section values for 11C in the 10B(p, p)10B reaction is shown. The data measured for the reaction channels p(10B,α) and p(10B,3He) is also presented. Interestingly, the cross sections for the 3He channel are observed upto 2 MeV below the lowest energy measurement available in literature.

New resonances in C11 above the B10 + p threshold investigated by inverse kinematic resonant scattering

The spectroscopy of $^{11}\mathrm{C}$ has been investigated by the resonant scattering of $^{10}\mathrm{B}+p$ with the thick target inverse kinematic method. The $^{1}\mathrm{H}(^{10}\mathrm{B},p)^{10}\mathrm{B}$ reaction was measured at ${\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}={180}^{\ensuremath{\circ}}, {170}^{\ensuremath{\circ}}, {160}^{\ensuremath{\circ}}, {150}^{\ensuremath{\circ}}$, and ${140}^{\ensuremath{\circ}}$ using a 35.93 MeV $^{10}\mathrm{B}$ beam. Resonances in $^{11}\mathrm{C}$ between the excitation energy of 9.6 and 11.8 MeV are observed. The excitation functions are compared with previous data using thin target direct kinematics measurements. A multichannel $R$-matrix calculation under the kinematics assumption of resonant elastic scattering is performed and the resonant parameters, such as the resonant energy ${E}_{x}$, the spin-parity ${J}^{\ensuremath{\pi}}$, and the proton-decay partial width ${\mathrm{\ensuremath{\Gamma}}}_{p}$ are extracted.

α -cluster structure in F19 and Ne19 in resonant scattering

The nuclear structure of $^{19}\mathrm{F}$ and $^{19}\mathrm{Ne}$ is important for understanding of $\ensuremath{\alpha}$ clustering in the $A=20$ mass region and in questions related to astrophysics. However, the only high-resolution broad angular and energy range study of the $^{19}\mathrm{F}$ resonance structure in $\ensuremath{\alpha}+^{15}\mathrm{N}$ scattering was published over 60 years ago, and a detailed analysis of complex excitation functions of overlapping resonances with several decay channels was simply impossible at that time. We performed a modern $R$-matrix analysis of these old data to assign spins and specify resonant parameters of levels up to excitation energy of 8.2 MeV in $^{19}\mathrm{F}$. We successfully tested our $R$-matrix parameters in a fit of the recent data on $\ensuremath{\alpha}+^{15}\mathrm{N}$ obtained by thick target inverse kinematics (TTIK) method at 180 degrees. We used the new parameters for $^{19}\mathrm{F}$ to fit TTIK data for $\ensuremath{\alpha}+^{15}\mathrm{O}$, the mirror resonant reactions. The comparison of the data for isobaric mirror resonant reactions provides an interesting insight into the nuclear structure.

Thick target inverse kinematics approach for neutron emission

We applied Thick Target Inverse Kinematics Method for a study of resonances decaying through neutron emission. As a test we used a well-studied, because of its role in s-process in stars, $^{13}$C($\alpha$; n) reaction. The observed energy resolution for the $^{13}$C($\alpha$; n) excitation function was $\sim$60 keV, the largest contributions coming from the time structure of the beam and the thickness of the neutron detector. These measurements demonstrated the high efficiency of the approach and revealed a disagreement with R-matrix calculations based on parameters of the most recent previous analysis.

Evidence for α -cluster structure in Ne21 in the first measurement of resonant O17+α elastic scattering

The first study of resonances in $^{17}$O+$\alpha$ elastic scattering was carried out using the Thick Target Inverse Kinematics (TTIK) method. The data were analyzed in the framework of an $\textit{R}$-matrix approach. Many $\alpha$-cluster states were found in the $^{21}$Ne excitation region of the 9-13 MeV excitation energy including the first observation of a broad $\textit{l}$=0 state in an odd-even nucleus, which is likely the analog of the broad 0$^+$ at 8 MeV in $^{20}$Ne. The observed structure in $^{21}$Ne appeared to be strikingly similar to that in $^{20}$Ne populated in the resonance $^{16}$O+$\alpha$ scattering. The results are also useful for refinement of data on an $^{17}$O($\alpha$,$\textit{n}$) reaction important for astrophysics.

Thick-target inverse kinematic method in order to investigate alpha-clustering in212Po

The inverse-kinematic thick-target method has been used in order to investigate 212Po alpha-structure by the elastic scattering of 208Pb on 4He target. A 208Pb beam, accelerated by the Superconducting Cyclotron (CS) of Laboratori Nazionali del Sud - INFN, at the incident energy of 10.1 A MeV was impinging onto a specifically designed 4He gas cell, two meter long. The gas cell wasacting both as target and as beam degrader, stopping the beam before reaching the alpha-particle detection system placed at 0° with respect to the beam axis. In order to disentangle the elastic contribution from other reaction channels (e.g. inelastic scattering) a microchannel plate was used to measure the Time of Flight(ToF) of both the 208Pb beam particles and the ejectiles along the gas cell. The 208Pbstopping power in the 4He gas target was also measured, as a key ingredient in order to establish theinteraction point inside the gas cell, in turn determining the solid angle covered by the detector. In the following, the experimental technique will be described, and the results of a preliminary data analysis will be shown.

Searching for states analogous to the C12 Hoyle state in heavier nuclei using the thick target inverse kinematics technique

Identification of alpha cluster states analogous to the 12C Hoyle state in heavier alpha- conjugate nuclei can provide tests of the existence of alpha condensates in nuclei. Such states are predicted for 16O, 20Ne, 24Mg, 28Si etc. at excitation energies slightly above the multi-alpha particle decay threshold, but have not yet been experimentally identified. The Thick Target Inverse Kinematics (TTIK) technique can be used to study the breakup of excited self-conjugate nuclei into many alpha particles. The reaction 20Ne+{\alpha} was studied using a 20Ne beam at 12 MeV/nucleon from the K150 cyclotron at Texas A&M University. The TTIK method was used to study both single {\alpha}-particle emission and multiple {\alpha}-particle decays. Events with alpha multiplicity up to four were analyzed. The analysis of the three {\alpha} - particle emission data allowed the identification of the Hoyle state and other 12C excited states decaying into three alpha particles. The results are shown and compared with other data available in the literature. Although the statistics for events with alpha multiplicity four is low, the data show a structure at about 15.2 MeV that could indicate the existence in 16O of a state analogous to the 12C Hoyle state. This structure is confirmed by the re-analysis of alpha multiplicity four events from a previous experiment performed at 9.7 MeV/nucleon with a similar setup but lower granularity. Moreover, the reconstructed excitation energy of 24Mg for these events peaks at around 34 MeV, very close to the predicted excitation energy for an excited state analogous to the 12C Hoyle state in 24Mg.

Direct measurements and detection techniques with low-energy RIBs

Astrophysical reactions involving radioactive isotopes (RI) are of importance for the stellar energy generation and nucleosynthesis especially in high-temperature astrophysical sites, such as X-ray bursts, core-collapse supernovae, and supermassive metalpoor stars. In spite of the essential diffculties in the experimental evaluation of those reaction rates, there are several successful approaches to study them, owing to the recent technical developments in the beam production, measurement method, and detectors. Among them, the measurements of α resonant scattering and (α, p) reactions using the thick-target method in inverse kinematics are discussed. The experiments at the low-energy RI beam separator CRIB, operated by Center for Nuclear Study (CNS), the University of Tokyo, are introduced as examples for such studies.

Nuclear astrophysics projects at the low-energy RI beam separator CRIB

Studies on nuclear reactions relevant for astrophysics have been performed using the radioactive-isotope (RI) beams at the low-energy RI beam separator CRIB, operated by Center for Nuclear Study (CNS), the University of Tokyo. A type of measurement to study astrophysical reactions at CRIB is by the elastic resonant scattering with the thick-target method in inverse kinematics. We introduce the α resonant scattering with 7 Be beam, related to the astrophysical 7 Be(α, γ) reactions, which is relevant in the hot p-p chain and νp-process in supernovae. Other α resonant scattering measurements with 30 S, 10 Be, 15 O, and 18 Ne beams have been performed at CRIB, using the thick-target method.

Implementation of TTIK method and time of flight for resonance reaction studies at heavy ion accelerator DC-60

To study resonance reactions of heavy ions at low energy we have combined the Thick Target Inverse Kinematics Method (TTIK) with Time of Flight method (TF). We used extended target and TF to resolve the identification problems of various possible nuclear processes inherent to the simplest popular version of TTIK. Investigations of the 15N interaction with hydrogen and helium gas targets by using this new approach are presented.

The cluster and single-particle states in 13C (α,α)13C reactions

The excitation functions of elastic scattering of 13C on alpha particle have been measured using the thick-target inverse kinematic method at the heavy ion DC-60 cyclotron. The helium gas was used as a target and also as a degrader to stop the beam. New data (including 180°degree) of the resonances close to the threshold in 17O have been obtained.

Two measurements of the22Na+p resonant scattering via thick-target inverse-kinematics method

Na-22 is an important isotope for the study of extinct radioactivity, meanwhile its sufficiently long half life provides the possibility to observe live Na-22 in nearby nova explosions. The Na-22(p,gamma)Mg-23 is one of the key reactions that influence the Na-22 abundance in nova ejecta. To study the proton resonant states in Mg-23 relevant to the astrophysical Na-22(p,gamma)Mg-23 reaction rates, two measurements have been carried out at the CRIB separator of University of Tokyo, and the RIBLL secondary beamline in Lanzhou, respectively. The Na-22 secondary beam was produced via the H-1(Ne-22,Na-22) n charge exchange reaction. Thick-target inverse-kinematics method is applied to obtain the excitation function of Na-22+ p elastic scattering. Extended gas target and solid state polyethylene foil were used in the two measurements, respectively, to map the different excitation energy region of the compound nucleus Mg-23. Several new resonant levels are observed and their contribution to the Na-22(p,gamma)Mg-23 reaction rate is evaluated.

Study of the excitation function for the 13C + 4He elastic scattering with the thick-target inverse kinematics method

The results of the study of the resonance α + 13C interaction using the thick-target inverse kinematic method at the heavy ion DC-60 cyclotron are presented. The helium gas was used as a target and also as a degrader to stop the beam. New data (including 180°-scattering) of the resonances close to the threshold in 17O have been obtained.

Exploring the alpha cluster structure of nuclei using the thick target inverse kinematics technique for multiple alpha decays

We explored alpha clustering in 24 Mg using the reaction 20 Ne+ and the Thick Target Inverse Kinematics (TTIK) technique. 20 Ne beams of energy 3.7 AMeV and 11 AMeV were delivered by the K150 cyclotron at Texas A&M University. The reaction chamber was filled with 4 He gas at a pressure sufficient to stop the beam before the detectors. The energy of the light reaction products was measured by three silicon detector telescopes. The time relative to the cyclotron radiofrequency was also measured. For the first time the TTIK method was used to study both single and multiple -particle decays. New results were obtained on elastic resonant  scattering, as well as on inelastic processes leading to high excitation energy systems decaying by multiple -particle emission. Preliminary results will be shown on events with -multiplicity one and two.

Resonant scattering of22Na + pstudied by the thick-target inverse-kinematic method

Background: In presolar low-density graphite grains, an extraordinarily large ${}^{22}$Ne/${}^{20}$Ne ratio or even nearly pure ${}^{22}$Ne is found, pointing to the condensation of radioactive ${}^{22}$Na in grains. Supernovae and neon-rich novae are the main events that produce ${}^{22}$Na via the explosive hydrogen burning process. The ${}^{22}$Na($p$, $\ensuremath{\gamma}$)${}^{23}$Mg reaction is one of the key reactions that influences the ${}^{22}$Na abundance in ejecta.Purpose:The present work aims to explore the proton resonant states in ${}^{23}$Mg relevant to the astrophysical ${}^{22}$Na($p$, $\ensuremath{\gamma}$)${}^{23}$Mg reaction. The determined ${}^{23}$Mg resonant parameters can be used to evaluate the ${}^{22}$Na($p$, $\ensuremath{\gamma}$)${}^{23}$Mg reaction rate.Method:A low-energy ${}^{22}$Na radioactive ion beam is produced via the ${}^{1}$H(${}^{22}$Ne, ${}^{22}$Na)$n$ reaction, and used to measure the experimental excitation function of the ${}^{22}$Na + $p$ resonant scattering with a conventional thick-target inverse kinematic method. $R$-matrix analysis is applied to deduce the ${}^{23}$Mg resonance parameters from the experimental excitation function.Results: Three proton resonance states in ${}^{23}$Mg are observed. Spins/parities and the proton partial widths are determined. The deduced excitation energies agree with the compiled values.Conclusions: The new spin and parity assignments allow us to perform a shell-model calculation of the $\ensuremath{\gamma}$ widths of the ${}^{23}$Mg resonant states for the evaluation of the ${}^{22}$Na($p$, $\ensuremath{\gamma}$)${}^{23}$Mg astrophysical reaction rate. The two $s$-wave resonant states established in this work at 8.793 and 8.916 MeV in ${}^{23}$Mg, respectively, increase the total reaction rate by about 5% at a temperature greater than 2 GK.

Angular distribution of 6He+p elastic scattering

The angular distribution of 1H(6He,p)6He elastic scattering has been measured at Ec.m. = 4.3 MeV by using a thick-target inverse kinematic method. The experimental differential cross sections are reproduced by the distorted-wave Born approximation calculation utilizing the CH89 global optical potential parameter set. The real part of CH89 is reduced comparing with other potentials, which may be attributed to the couplings necessary for the weakly bound nuclei.

Isobaric analog resonances of theN=21nucleus35Si

Neutron single-particle states in the neutron-rich nucleus ${}^{35}$Si, which is located beside the $N=20$ shell breaking nucleus ${}^{32}$Mg, were investigated through their isobaric analog resonances. The excitation function for ${}^{34}$Si$+p$ elastic scattering was measured around ${0}^{\ensuremath{\circ}}$ in the laboratory frame by the thick target inverse kinematics method with a ${}^{34}$Si beam around 5 MeV/nucleon and a thick polyethylene target. Eight resonances were successfully observed. Angular momenta and proton and total widths of the resonances were assigned using $R$-matrix analysis. With the help of information of the $\ensuremath{\beta}$ decay study, six isobaric analog resonances were identified. Spectroscopic factors and spin-parities of the corresponding parent states in ${}^{35}$Si are presented.

Proton resonance elastic scattering in inverse kinematics on the medium heavy nucleus 68Zn

An isobaric analog resonance of 69Zn was studied by the resonance elastic scattering of p ( 68Zn , p with a 5.5MeV/nucleon 68Zn beam and a thick polyethylene target. The excitation function of the differential cross-section of proton elastic scattering was measured around 0 degrees in the laboratory frame by the thick target inverse kinematics method. The angular momentum, and proton and total widths of the resonance assigned using an R -matrix calculation are in good agreement with earlier measurements performed using normal kinematics, demonstrating that the thick target inverse kinematics method is a useful tool for studying the single-particle structures of neutron-rich nuclei.

Highly excited alpha-cluster states in 32S studied with the thick-target inverse kinematics method

Excitation functions of elastic 28Si + $ \alpha$ scattering were measured employing the relatively new thick-target inverse kinematics technique, confirming the usefulness of the method. Data were taken at a 28Si beam energy of 150MeV in a reaction chamber filled with 4He gas, corresponding to the excitation region of 10-24MeV in 32S . Results are compared to earlier studies, in order to validate the method and explore its limitations. The data were treated in the framework of a simplified R -matrix approach. Energies, widths and spin assignments were obtained for 129 resonances in this mid-shell nucleus. The structure is discussed within the concept of $ \alpha$ -cluster structure in the quasi-continuum of 32S .