Structure of 23Al from one-proton breakup reaction and astrophysical implications
A. Banu, L. Trache, F. Carstoiu, NL Achouri, A Bonaccorso, WN Catford, M Chartier, M Dimmock, B Fernandez-Dominguez, M Freer, L Gaudefroy, M Horoi, M Labiche, B… 展开作者
A. Banu, L. Trache, F. Carstoiu, NL Achouri, A Bonaccorso, WN Catford, M Chartier, M Dimmock, B Fernandez-Dominguez, M Freer, L Gaudefroy, M Horoi, M Labiche, B Laurent, RC Lemmon, F Negoita, NA Orr, S Paschalis, N Patterson, ES Paul, M Petri, B Pietras, BT Roeder, F Rotaru, P Roussel-Chomaz, E Simmons, GS Thomas, RE Tribble
The ground state of the proton-rich nucleus 23Al has been studied by one-proton removal on a carbon target at about 50 MeV/nucleon using the EXOGAM + SPEG experimental setup at GANIL. Longitudinal momentum distributions of the 22Mg breakup fragments, inclusive and in coincidence with gamma rays de-exciting the residues, were measured. The ground-state structure of 23Al is found to be a configuration mixing of a d-orbital valence proton coupled to four core states - 0$^{+}_{gs}$, 2$^{+}_{1}$, 4$^{+}_{1}$, 4$^{+}_{2}$. We confirm the ground state spin and parity of 23Al as $J^π = 5/2^{+}$. The measured exclusive momentum distributions are compared with extended Glauber model calculations to extract spectroscopic factors and asymptotic normalization coefficients (ANCs). The spectroscopic factors are presented in comparison with those obtained from large-scale shell model calculations. We determined the asymptotic normalization coefficient of the nuclear system $^{23}$Al$_{gs}$ $\rightarrow$ $^{22}$Mg(0$^{+}$) + p to be $C^{2}_{d_{5/2}}$($^{23}Al_{gs}$) = (3.90 $\pm$ 0.44) $\times$ 10$^{3}$ fm$^{-1}$, and used it to infer the stellar reaction rate of the direct radiative proton capture $^{22}$Mg(p,$γ$)$^{23}$Al. Astrophysical implications related to $^{22}$Na nucleosynthesis in ONe novae and the use of one-nucleon breakup at intermediate energies as an indirect method in nuclear astrophysics are discussed.
We show that asymptotic normalization coefficients (ANC) can be extracted from one nucleon breakup reactions of loosely bound nuclei at 30-300 MeV/u. In particular, the breakup of ^{8}B is described in terms of an extended Glauber model. The 8B ANC extracted for the ground state of this nucleus from breakup data at several energies and on different targets, C^2 = 0.450+/-0.039} fm^-1, leads to the astrophysical factor S_{17}(0)= 17.4+/-1.5 eVb for the key reaction for solar neutrino production 7Be(p,gamma)8B. The procedure described here is more general, providing an indirect method to determi…
High precision cross-section data of the deuteron-proton breakup reaction at 130 MeV deuteron energy are compared with the theoretical predictions obtained with a coupled-channel extension of the CD Bonn potential with virtual Delta-isobar excitation, without and with inclusion of the long-range Coulomb force. The Coulomb effect is studied on the basis of the cross-section data set, extended in this work to about 1500 data points by including breakup geometries characterized by small polar angles of the two protons. The experimental data clearly prefer predictions obtained with the Coulomb int…
A study of the deuteron breakup reaction $pd \to (pp)n$ with forward emission of a fast proton pair with small excitation energy $E_{pp}<$ 3 MeV has been performed at the ANKE spectrometer at COSY--Jülich. An exclusive measurement was carried out at six proton--beam energies $T_p=$~0.6,~0.7,~0.8,~0.95,~1.35, and 1.9 GeV by reconstructing the momenta of the two protons. The differential cross section of the breakup reaction, averaged up to $8^{\circ}$ over the cm polar angle of the total momentum of the $pp$ pairs, has been obtained. Since the kinematics of this process is quite similar to that…
Proton-proton correlations and correlations of protons, deuterons and tritons with alpha particles from spectator decays following 197Au + 197Au collisions at 1000 MeV per nucleon have been measured with two highly efficient detector hodoscopes. The constructed correlation functions, interpreted within the approximation of a simultaneous volume decay, indicate a moderate expansion and low breakup densities, similar to assumptions made in statistical multifragmentation models. PACS numbers: 25.70.Pq, 21.65.+f, 25.70.Mn, 25.75.Gz
The 9Be(28Mg,27Na) one-proton removal reaction with a large proton separation energy of Sp(28Mg)=16.79 MeV is studied at intermediate beam energy. Coincidences of the bound 27Na residues with protons and other light charged particles are measured. These data are analyzed to determine the percentage contributions to the proton removal cross section from the elastic and inelastic nucleon removal mechanisms. These deduced contributions are compared with the eikonal reaction model predictions and with the previously measured data for reactions involving the re- moval of more weakly-bound protons f…
We study dynamical effects in proton breakup from a weakly bound state in an exotic nucleus on a heavy target. The Coulomb interactions between the proton and the core and the proton and the target are treated to all orders, including also the full multipole expansion of the Coulomb potential. The dynamics of proton nuclear and Coulomb breakup is compared to that of an equiva- lent neutron of larger binding energy in order to elucidate the differences with the well understood neutron breakup mechanism. A number of experimentally measurable observables such as parallel momentum distributions, p…
Vector and tensor analysing powers of the d(pol)p->(pp)n (charge-exchange) and d(pol)p->(pn)p (non-charge-exchange) breakup reactions have been measured with the ANKE spectrometer at the COSY ring at a deuteron beam energy of 1170 MeV for small momentum transfers to the low excitation energy (pp) or (pn) systems. A quantitative understanding of the values of A_xx and A_yy for the charge-exchange reaction is provided by impulse approximation calculations. The data suggest that spin-flip isospin-flip transitions, which dominate the charge-exchange breakup of the deuteron, are also important in t…
We have used existing data on the one-proton-removal cross section of 9C at 285 MeV/u and Glauber model calculations to extract the asymptotic normalization coefficient for the wave function of the last proton in the ground state of 9C. The calculations are done first using folded potentials starting from two different effective nucleon-nucleon interactions and second in the optical limit using three nucleon-nucleon interactions, and the results are found to be consistent, with no new parameters adjusted. We find C^2(p3/2)+C^2(p1/2)=1.22+/- fm-1. From this result we obtain the astrophysical fa…
The two-proton removal reaction from 28Mg projectiles has been studied at 93 MeV/u at the NSCL. First coincidence measurements of the heavy 26Ne projectile residues, the removed protons and other light charged particles enabled the relative cross sections from each of the three possible elastic and inelastic proton removal mechanisms to be determined. These more final-state-exclusive measurements are key for further interrogation of these reaction mechanisms and use of the reaction channel for quantitative spectroscopy of very neutron-rich nuclei. The relative and absolute yields of the three …
In this paper we show how effective parameters such as effective binding energies can be defined for a proton in the combined nuclear-Coulomb potential, including also the target potential, in the case in which the proton is bound in a nucleus which is partner of a nuclear reaction. Using such effective parameters the proton behaves similarly to a neutron. In this way some unexpected results obtained from dynamical calculations for reactions initiated by very weakly bound proton halo nuclei can be interpreted. Namely the fact that stripping dominates the nuclear breakup cross section which in …
Proton-proton correlations from spectator decays following Au + Au collisions at 1000 AMeV have been measured with an highly efficient detector hodoscope. The constructed correlation functions indicate a moderate expansion and low breakup densities similar to assumptions made in statistical multifragmentation models. In agreement with a volume breakup rather short time scales were deduced employing directional cuts in proton-proton correlations.
Three- and four-cluster breakup reactions in the ${}^{16}$C-proton scattering are studied using three-body core-neutron-neutron model for ${}^{16}$C. Single-scattering approximation (SSA) of four-particle equations for transition operators is used to calculate three- and four-cluster breakup amplitudes at 200 and 300 MeV/nucleon energy near proton-neutron ($pn$) quasi free scattering (QFS) conditions. The differential cross section is sharply peaked at $pn$ QFS point and decreases rapidly whenever kinematical conditions deviate from $pn$ QFS. The accuracy of the SSA for the three-cluster break…
We study the elastic scattering of polarized protons from He isotopes. The central and spin-orbit parts of the optical potential are derived using the Glauber theory that can naturally take account of the breakup effect of the He isotopes. Both the differential cross section and the vector analyzing power for $p+^{4,6,8}$He scattering at 71 MeV are in reasonable agreement with experiment. Scattering observables at 300 MeV are predicted. The Pauli blocking effect is examined at 71 MeV.
Differential cross sections for deuteron breakup $^{1}H(d, pp)n$ reaction were measured for a large set of 243 geometrical configurations at the beam energy of 80 MeV/nucleon. The cross section data are normalized by the luminosity factor obtained on the basis of simultaneous measurement of elastic scattering channel and the existing cross section data for this process. The results are compared to the theoretical calculations modeling nuclear interaction with and without taking into account the three-nucleon force (3NF) and Coulomb interaction. In the validated region of the phase space both t…
We present a semiclassical method to treat the proton breakup from a weakly bound state in an exotic nucleus. The Coulomb interactions between the proton, core and target are treated to all orders and including the full multipole expansion of the Coulomb potential. The nuclear proton-target interaction is also treated to all orders. The core-target interaction is included as an absorption. The method is semi-analytical thus allowing for a detailed understanding of the short range and long range effects of the interactions in the reaction dynamics. It explains also the origin of possible asymme…
This paper gives new insight to the study of dynamical effects in proton breakup as compared to neutron breakup from a weakly bound state in an exotic nucleus. Following our recent work [Ravinder Kumar and Angela Bonaccorso, Phys. Rev. C84 014613 (2011)] there has been some discussion in the literature [B. Paes, J. Lubiana, P.R.S. Gomes, V. Guimarães, Nucl. Phys. A890 1 (2012); Y. Kucuk and A. M. Moro, Phys. Rev. C86 034601 (2012)], thus in order to clarify and asses quantitatively which mechanism would dominate measured observables, we study here several reaction mechanisms separately but als…
Angular distributions of oxygen produced in the breakup of $^{17}$F incident on a $^{208}$Pb target have been measured around the grazing angle at beam energies of 98 and 120 MeV. The data are dominated by the proton stripping mechanism and are well reproduced by dynamical calculations. The measured breakup cross section is approximately a factor of 3 less than that of fusion at 98 MeV. The influence of breakup on fusion is discussed.
Proton-proton correlations and correlations of p-alpha, d-alpha, and t-alpha from spectator decays following Au + Au collisions at 1000 AMeV have been measured with an highly efficient detector hodoscope. The constructed correlation functions indicate a moderate expansion and low breakup densities similar to assumptions made in statistical multifragmentation models. In agreement with a volume breakup rather short time scales were deduced employing directional cuts in proton-proton correlations. PACS numbers: 25.70.Pq, 21.65.+f, 25.70.Mn
High precision cross-section data of the deuteron-proton breakup reaction at 130 MeV are presented for 72 kinematically complete configurations. The data cover a large region of the available phase space, divided into a systematic grid of kinematical variables. They are compared with theoretical predictions, in which the full dynamics of the three-nucleon (3N) system is obtained in three different ways: realistic nucleon-nucleon (NN) potentials are combined with model 3N forces (3NF's) or with an effective 3NF resulting from explicit treatment of the Delta-isobar excitation. Alternatively, the…
The momentum distribution of $^{11}$Be fragments produced by the breakup of $^{12}$Be interacting with a proton target at 700.5 MeV/$u$ energy has been measured at GSI Darmstadt. To obtain the structure information on the anomaly of the $N=8$ neutron shell, the momentum distribution of $^{11}$Be fragments from the one-neutron knockout $^{12}$Be(p,pn) reaction, measured in inverse kinematics, has been analysed in the distorted wave impulse approximation (DWIA) based on a quasi-free scattering scenario. The DWIA analysis shows a surprisingly strong contribution of the neutron $0d_{5/2}$ orbital …
Breakup reactions of loosely-bound nuclei are often used to extract structure and/or astrophysical information. Here we compare three non-perturbative reaction theories often used when analyzing breakup experiments, namely the continuum discretized coupled channel model, the time-dependent approach relying on a semiclassical approximation, and the dynamical eikonal approximation. Our test case consists of the breakup of 15C on Pb at 68 MeV/nucleon and 20 MeV/nucleon.
The angular distribution for the breakup of 8B into 7Be+p on a 58Ni target has been measured at an incident energy of 25.75 MeV. The data are inconsistent with first-order theories but are remarkably well described by calculations including higher-order effects. The comparison with theory illustrates the importance of the exotic proton halo structure of 8B in accounting for the observed breakup angular distribution.
The structure of the unbound nuclei 9He, 10Li and 13Be has been explored using breakup and proton-knockout from intermediate energy 11Be and 14,15B beams. In the case of both N=7 isotones, virtual s-wave strength is observed near threshold together with a higher-lying resonance. A very narrow structure at threshold in the 12Be+n relative energy spectrum is demonstrated to arise from the decay of the 14Be*(2+), discounting earlier reports of a strong virtual s-wave state in 13Be.
Angular distributions of fluorine and oxygen produced from 170 MeV 17^F incident on 208^Pb were measured. The elastic scattering data are in good agreement with optical model calculations using a double-folding potential and parameters similar to those obtained from 16^O+208^Pb. A large yield of oxygen was observed near θ_lab=36 deg. It is reproduced fairly well by a calculation of the (17^F,16^O) breakup, which is dominated by one-proton stripping reactions. The discrepancy between our previous coincidence measurement and theoretical predictions was resolved by including core absorption in th…
The formation of continuum neutron distribution in $^7$Li(p,n) has been identified as due to the coupling of the $^7$Be breakup levels to the final state of the reaction. The continuum neutron spectra produced by $^7$Li(p,n) reaction has been estimated by measuring the double differential cross sections for continuum and resonant breakup of $^7$Be, through $^7$Li(p,n)$^7$Be$^*$ reaction at 21 MeV of proton energy. The breakup contributions from continuum and $5/2^-$, $7/2^-$ states of $^7$Be have been identified. The measured double differential cross sections have been reproduced through CDCC…
We discuss the use of one-nucleon breakup reactions of loosely bound nuclei at intermediate energies as an indirect method in nuclear astrophysics. These are peripheral processes, therefore we can extract asymptotic normalization coefficients (ANC) from which reaction rates of astrophysical interest can be inferred. To show the usefulness of the method, three different cases are discussed. In the first, existing experimental data for the breakup of 8B at energies from 30 to 1000 MeV/u and of 9C at 285 MeV/u on light through heavy targets are analyzed. Glauber model calculations in the eikonal …
The 15O(alpha,gamma)19Ne reaction plays a role in the ignition of Type I x-ray bursts on accreting neutron stars. The lifetimes of states in 19Ne above the 15O + alpha threshold of 3.53 MeV are important inputs to calculations of the astrophysical reaction rate. These levels in 19Ne were populated in the 3He(20Ne,alpha)19Ne reaction at a 20Ne beam energy of 34 MeV. The lifetimes of six states above the threshold were measured with the Doppler shift attenuation method (DSAM). The present measurements agree with previous determinations of the lifetimes of these states and in some cases are consi…
The present paper reports high-accuracy cross-section data for the 2H(n,nnp) reaction in the neutron-proton (np) and neutron-neutron (nn) final-state-interaction (FSI) regions at an incident mean neutron energy of 13.0 MeV. These data were analyzed with rigorous three-nucleon calculations to determine the 1S0 np and nn scattering lengths, a_np and a_nn. Our results are a_nn = -18.7 +/- 0.6 fm and a_np = -23.5 +/- 0.8 fm. Since our value for a_np obtained from neutron-deuteron (nd) breakup agrees with that from free np scattering, we conclude that our investigation of the nn FSI done simultaneo…
The astrophysical factor of the 8B(p,gamma)9C at zero energy, S18(0), is determined from three-body model analysis of 9C breakup processes. The elastic breakup 208Pb(9C,p8B)208Pb at 65 MeV/nucleon and the one-proton removal reaction of 9C at 285 MeV/nucleon on C and Al targets are calculated with the continuum-discretized coupled-channels method (CDCC) and the eikonal reaction theory (ERT), respectively. The asymptotic normalization coefficient (ANC) of 9C in the p-8B configuration extracted from the two reactions show good consistency, in contrast to in the previous studies. As a result of th…
Deuteron-deuteron elastic scattering and transfer reactions in the energy regime above four-nucleon breakup threshold are described by solving exact four-particle equations for transition operators. Several realistic nuclear interaction models are used, including the one with effective many-nucleon forces generated by the explicit $Δ$-isobar excitation; the Coulomb force between protons is taken into account as well. Differential cross sections, deuteron analyzing powers, outgoing nucleon polarization, and deuteron-to-neutron polarization transfer coefficients are calculated at 10 MeV deuteron…
The available data on the forward charge exchange of nucleons on the deuteron up to 2GeV per nucleon are reviewed. The value of the inclusive nd->pnn/np->pn cross section ratio is sensitive to the fraction of spin-independent neutron-proton backward scattering. The measurements of the polarisation transfer in d(\vec{n},\vec{p})nn or the deuteron analysing power in p(\vec{d},pp)n in high resolution experiments, where the final nn or pp pair emerge at low excitation energy, depend upon the longitudinal and transverse spin-spin np amplitudes. The relation between these types of experiments is dis…
Differential cross section for the 1H(d,pp)n breakup reaction at deuteron beam energy of 340 MeV has been measured with the use of WASA detector at COSY-Juelich. The set of proton-proton coincidences registered at Forward Detector has been analysed on dense grid of kinematic variables, giving in total around 5600 data points. The cross section data are compared to theoretical predictions based on the state-of-the-art nucleon-nucleon potentials, combined with three-nucleon force, Coulomb interaction or carried out in a relativistic regime.
The Ayy data for deuteron inclusive breakup off hydrogen and carbon at a deuteron momentum of 9.0 GeV/c and large Pt of emitted protons are presented. The large values of Ayy independent of the target mass reflect the sensitivity of the data to the deuteron spin structure. The data obtained at fixed $x$ and plotted versus Pt clearly demonstrate the dependence of the deuteron spin structure at short internucleonic distances on two variables. The data are compared with the calculations using Paris, CD-Bonn and Karmanov's deuteron wave functions.
Previous studies of $(d,p)$ reactions in three-body (proton, neutron, nuclear core) systems revealed a nontrivial effect of the core excitation: the transfer cross section cannot be factorized into the spectroscopic factor and the single-particle cross section obtained neglecting the core excitation. This observable, up to a kinematic factor, is the angular distribution of the core nucleus in the $(p,d)$ reaction. The study of the core excitation effect for the most closely related observable in the $(p,pn)$ three-body breakup, i.e., the core angular distribution, is aimed in the present work.…
$\rm S^*(E)$ measurement of the $\rm {}^{12}C({}^{12}C,α){}^{20}Ne$ reaction at astrophysical energies via the Trojan horse method with $\rm ^{16}O$ quasi-free breakup
Institute of Radiation Technology, Beijing Academy of Science and Technology（北京辐射技术研究所，北京 Akademija 科学技术研究院）；Department of Nuclear Physics, China Institute of Atomic Energy（原子能科学研究院核物理系）；School of Physics and Materials Science, Anhui University（安徽大学物理与材料科学学院）
Background: Theoretical calculations of the four-particle scattering above the four-cluster breakup threshold are technically very difficult due to nontrivial singularities or boundary conditions. Further complications arise when the long-range Coulomb force is present. Purpose: We aim at calculating proton-${}^3$He elastic scattering observables above three- and four-cluster breakup threshold. Methods: We employ Alt, Grassberger, and Sandhas (AGS) equations for the four-nucleon transition operators and solve them in the momentum-space framework using the complex-energy method whose accuracy a…
The $^9$C nucleus and related capture reaction, ${^8\mathrm{B}}(p,γ){^9\mathrm{C}}$, have been intensively studied with an astrophysical interest. Due to the weakly-bound nature of $^9$C, its structure is likely to be described as the three-body (${^7\mathrm{Be}}+p+p$). Its continuum structure is also important to describe reaction processes of $^9$C, with which the reaction rate of the ${^8\mathrm{B}}(p,γ){^9\mathrm{C}}$ process have been extracted indirectly. We perform three-body calculations on $^9$C and discuss properties of its ground and low-lying states via breakup reactions. We employ…
The proton capture cross sections of the two most proton rich, stable isotopes of Cadmium have been measured for the first time in the energy range relevant to the astrophysical p-process between Ep=2.4 and 4.7MeV. The 106Cd(p,gamma)107In and 108Cd(p,gamma)109In cross sections have been determined using the activation technique. Highly enriched as well as natural Cd targets have been irradiated with proton beams from both the Van de Graaff and Cyclotron accelerators of the ATOMKI. The cross sections have been derived by measuring the gamma-radiation following the beta-decay of the 107In and 10…
The data on investigation of inelastic interactions of $16^O$ nuclei with a proton at 3.25 A GeV/c momentum by the bubble chamber method are presented. The separate characteristics as fragments isotopic composition and as topo-logical cross sections of fragmentation channels are given. The processes of light fragments formation and breakup of $16^O$ nucleus on multicharge fragments have been investigated. The comparison of experimental data with the calculations by statistical multifragmentation model was conducted.
Exact four-body equations of Alt, Grassberger and Sandhas are solved for neutron-${}^3\mathrm{He}$ and proton-${}^3\mathrm{H}$ scattering in the energy regime above the four-nucleon breakup threshold. Cross sections and spin observables for elastic, transfer, charge-exchange, and breakup reactions are calculated using realistic nucleon-nucleon interaction models, including the one with effective many-nucleon forces due to explicit $Δ$-isobar excitation. The experimental data are described reasonably well with only few exceptions such as vector analyzing powers.
The astrophysical factor of $^8$B($p$,$γ$)$^9$C at zero energy, $S_{18}(0)$, is determined by a three-body coupled-channels analysis of the transfer reaction $^{8}$B($d$,$n$)$^{9}$C at 14.4 MeV/nucleon. Effects of the breakup channels of $d$ and $^9$C are investigated with the continuum-discretized coupled-channels method. It is found that, in the initial and final channels, respectively, the transfer process through the breakup states of $d$ and $^9$C, its interference with that through their ground states in particular, gives a large increase in the transfer cross section. The finite-range e…
The cross sections of the 70Ge(p,gamma)71As and 76Ge(p,n)76As reactions have been measured with the activation method in the Gamow window for the astrophysical p process. The experiments were carried out at the Van de Graaff and cyclotron accelerators of ATOMKI. The cross sections have been derived by measuring the decay gamma-radiation of the reaction products. The results are compared to the predictions of Hauser-Feshbach statistical model calculations using the code NON-SMOKER. Good agreement between theoretical and experimental S factors is found. Based on the new data, modifications of th…
As a continuation of a systematic study of reactions relevant to the astrophysical p process, the cross sections of the 74,76Se(p,gamma)75,77Br and 82Se(p,n)82Br reactions have been measured at energies from 1.3 to 3.6 MeV using an activation technique. The results are compared to the predictions of Hauser-Feshbach statistical model calculations using the NON-SMOKER and MOST codes. The sensitivity of the calculations to variations in the optical proton potential and the nuclear level density was studied. Good agreement between theoretical and experimental reaction rates was found for the react…
Nucleon transfer reactions in deuteron-deuteron collisions at energies above the three- and four-body breakup threshold are described using exact four-body equations for transition operators that are solved in the momentum-space framework. Differential cross sections, analyzing powers, polarizations, and spin transfer coefficients are obtained using realistic two-nucleon potentials and including the Coulomb repulsion between protons. Overall good agreement between predictions and experimental data is found. Most remarkable discrepancies are seen around the minima of the differential cross sect…
Reactions involving the group of nuclei commonly known as p nuclei are part of the nucleosynthetic mechanisms at astrophysical sites. The $^{113}$In nucleus is such a case with several open questions regarding its origin at extreme stellar environments. In this work, the experimental study of the cross sections of the radiative proton-capture reaction $^{112}$Cd(p,$γ$)$^{113}$In is attempted for the first time at energies lying inside the Gamow window with an isotopically enriched $^{112}$Cd target. Two different techniques, the in-beam $γ$-ray spectroscopy and the activation method, have been…
The cross section of the radiative proton capture reaction on the drip line nucleus 12N was investigated using the Asymptotic Normalization Coefficient (ANC) method. We have used the 14N(12N,13O)13C proton transfer reaction at 12 MeV/nucleon to extract the ANC for 13O -> 12N + p and calculate from it the direct component of the astrophysical S factor of the 12N(p,gamma)13O reaction. The optical potentials used and the DWBA analysis of the proton transfer reaction are discussed. For the entrance channel, the optical potential was inferred from an elastic scattering measurement carried out at th…
Three-nucleon scattering equations with irreducible three-nucleon force are solved in momentum-space. The Coulomb interaction between the two protons is included using the method of screening and renormalization. The need for the renormalization of the scattering amplitudes is demonstrated numerically. The Coulomb and Urbana IX three-nucleon force effects on the observables of elastic proton-deuteron scattering and breakup are studied.
The total cross sections for the 120Te(p,gamma)121I and 120Te(p,n)120I reactions have been measured by the activation method in the effective center-of-mass energies between 2.47 MeV and 7.93 MeV. The targets were prepared by evaporation of 99.4 % isotopically enriched 120Te on Aluminum and Carbon backing foils, and bombarded with proton beams provided by the FN tandem accelerator at the University of Notre Dame. The cross sections and $S$ factors were deduced from the observed gamma ray activity, which was detected off-line by two Clover HPGe detectors mounted in close geometry. The results a…
In nuclear astrophysics, the experimental scenario is still unclear for BBN relevant energies from 30-300 keV. Here, we report our measurements of cross section and astrophysical S(E) factor for pd capture reaction using proton beam energies 66 keV, 116 keV and 166 keV. Realistic GEANT4 simulations were carried out in order to estimate the energy dependent efficiency of the detector. The measured cross section and astrophysical S(E) factor for three new incident proton energies are found to be in good agreement, within the errors, with the values reported in the literature.
A kinematically complete measurement of the four-body breakup reaction d+2H-->2ps+2ns --> p +p +n +n has been performed at 15 MeV deuteron beam of the SINP MSU. The two protons and neutron were detected at angles close to those of emission of 2ps and 2ns systems. The energy of singlet dineutron state was determined by comparing experimental TOF spectrum of breakup neutrons with simulated spectra depending on this energy. A low value Enn = 0.076 +/- 0.006 keV obtained by fitting procedure apparently indicates an effective enhancement of nn-interaction in the intermediate state of studied reacti…
Nuclear transparency, Tp(A), is a measure of the average probability for a struck proton to escape the nucleus without significant re-interaction. Previously, nuclear transparencies were extructed for quasi-elastic A(e,e'p) knockout of protons with momentum below the Fermi momentum, where the spectral functions are well known. In this paper we extract a novel observable, the transparency ratio, Tp(A)/T_p(12C), for knockout of high-missing-momentum protons from the breakup of short range correlated pairs (2N-SRC) in Al, Fe and Pb nuclei relative to C. The ratios were measured at momentum transf…
A kinematically complete measurement was made of the Coulomb dissociation of 8B nuclei on a Pb target at 83 MeV/nucleon. The cross section was measured at low relative energies in order to infer the astrophysical S factor for the 7Be(p,gamma)8B reaction. A first-order perturbation theory analysis of the reaction dynamics including E1, E2, and M1 transitions was employed to extract the E1 strength relevant to neutrino-producing reactions in the solar interior. By fitting the measured cross section from Erel = 130 keV to 400 keV, we find S17(0) = 17.8 (+1.4, -1.2) eV b.
The study of d(d,p)t reaction is very important for the nucleosynthesis in both standard Big Bang and stellar evolution, as well as for the future fusion reactors planning of energy production. The d(d,p)t bare nucleus astrophysical S(E) factor has been measured indirectly at energies from about 400 keV down to several keV by means of the Trojan horse method applied to the quasi-free process $\rm {}^2H({}^6Li,pt){}^4He$ induced at a lithium beam energy of 9.5 MeV, which is closer to the zero quasi-free energy point. An accurate analysis leads to the determination of the $\rm S_{bare}(0)=56.7 \…
This dissertation investigated selected processes involving baryons and nuclei in hard scattering reactions. Through these processes, this work explored the constituent structure of baryons and the mechanisms through which the interactions between these constituents ultimately control the selected reactions. First, hard nucleon-nucleon elastic scattering was studied considering the quark exchange (QE) between the nucleons to be the dominant mechanism of interaction in the constituent picture. It was found that an angular asymmetry exhibited by proton-neutron (pn) elastic scattering data is exp…
Isotopic effects in spectator fragmentations following heavy-ion collisions at relativistic energies are investigated using data from recent exclusive experiments with SIS beams at GSI. Reactions of 12C on 112,124Sn at incident energies 300 and 600 MeV per nucleon were studied with the INDRA multidetector while the fragmentation of stable 124Sn and radioactive 107Sn and 124La projectiles was studied with the ALADIN spectrometer. The global characteristics of the reactions are very similar. This includes the rise and fall of fragment production and deduced observables as, e.g., the breakup temp…
The proton capture on the unstable nuclei plays a very important role for the nucleonsynthesis. The 12N(p,g)13O reaction rates at the energies of astrophysical interests are estimated with the spectroscopic factor and asymptotic normalization coefficient methods. The present results show that the 12N(p,g)13O reaction may play an important role in x-ray bursts.
We have measured the gamma-ray line production cross sections in proton-induced nuclear reactions on various target nuclei abundant in astrophysical sites over the incident energy range of Ep = 30 - 200 MeV. We carried out experimental campaigns in joint collaboration at the K = 200 cyclotron of iThemba LABS using a high-energy resolution, high-efficiency detection array composed of 8 Compton-suppressed clover detectors comprising 32 HP-Ge crystals for recording the gamma-ray spectra. In the current paper, we focus on de-excitation lines produced in proton irradiations of natC and Mylar target…
The (p,$γ$) cross sections of three stable Sr isotopes have been measured in the astrophysically relevant energy range. These reactions are important for the $p$-process in stellar nucleosynthesis and, in addition, the reaction cross sections in the mass region up to 100 are also of importance concerning the $rp$-process associated with explosive hydrogen and helium burning. It is speculated that this $rp$-process could be responsible for a certain amount of $p$-nuclei in this mass region. The (p,$γ$) cross sections of $^{84,86,87}$Sr isotopes were determined using an activation technique. The…
