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Prostate-specific membrane antigen (PSMA) positron emission tomography (PET) can be used to locate lesions based on PSMA avidity, however guidelines on its use are limited by its infancy. We aimed to compare multiparametric magnetic resonance imaging (mpMRI) and PSMA PET/CT to prostatectomy histopathology. We conducted a chart review from February 2015 to January 2017 of 50 male patients staged for prostate cancer using PSMA PET/CT and mpMRI who then underwent radical prostatectomy. Pre-operative PSMA PET/CT and mpMRI were paired with corresponding histopathology. Correlations, sensitivity, and specificity were used for comparisons. A total of 81 lesions were confirmed by histopathology. Fifty index lesions were detected by histopathology, all of which were detected by PSMA PET/CT (100% detection), and 47 by mpMRI (94% detection). Thirty-one histologically confirmed secondary lesions were detected, 29 of which were detected by PSMA PET/CT (93.5% detection), and 16 by mpMRI (51.6% detection). PSMA had better sensitivity for index lesion localization than mpMRI (81.1 vs. 64.8%). Specificity was similar for PSMA PET/CT and mpMRI (84.6 vs. 82.7%). SUVmax of index lesions ranged from 2.9 to 39.6 (M = 9.27 ± 6.41). Index lesion SUVmax was positively correlated with PSA (rho = 0.48, p

We have studied the ground state of the unbound, very neutron-rich isotope of hydrogen $^{5}\mathrm{H}$, using the $^{6}\mathrm{He}(d,^{3}\mathrm{He})^{5}\mathrm{H}$ reaction in inverse kinematics at a bombarding energy of $E(^{6}\mathrm{He})=55A$ MeV. The present results suggest a ground-state resonance energy ${E}_{R}=2.4\ifmmode\pm\else\textpm\fi{}0.3$ MeV above the $^{3}\mathrm{H}+2n$ threshold, with an intrinsic width of $\mathrm{\ensuremath{\Gamma}}=5.3\ifmmode\pm\else\textpm\fi{}0.4$ MeV in the $^{5}\mathrm{H}$ system. Both the resonance energy and width are higher than those reported in some, but not all previous studies of $^{5}\mathrm{H}$. The previously unreported $^{6}\mathrm{He}(d,t)^{5}\mathrm{He}_{\mathrm{g}.\mathrm{s}.}$ reaction is observed in the same measurement, providing a check on the understanding of the response of the apparatus. The data are compared to expectations from direct two-neutron and dineutron decay. The possibility of excited states of $^{5}\mathrm{H}$ populated in this reaction is discussed using different calculations of the $^{6}\mathrm{He}\ensuremath{\rightarrow}^{5}\mathrm{H}+p$ spectroscopic overlaps from shell-model and ab initio nuclear-structure calculations.

We have studied the $^{14,15}\mathrm{C}(d,^{3}\mathrm{He})^{13,14}\mathrm{B}$ proton-removing reactions in inverse kinematics. The $(d,^{3}\mathrm{He})$ reaction probes the proton occupation of the target ground state, and also provides spectroscopic information about the final states in $^{13,14}\mathrm{B}$. The experiments were performed using $^{14,15}\mathrm{C}$ beams from the ATLAS accelerator at Argonne National Laboratory. The reaction products were analyzed with the HELIOS device. Angular distributions were obtained for transitions from both reactions. The $^{14}\mathrm{C}$-beam data reveal transitions to excited states in $^{13}\mathrm{B}$ that suggest configurations with protons outside the $\ensuremath{\pi}(0{p}_{3/2})$ orbital, and some possibility of proton cross-shell $0p\text{\ensuremath{-}}1s0d$ excitations, in the $^{14}\mathrm{C}$ ground state. The $^{15}\mathrm{C}$-beam data confirm the existence of a broad ${2}^{\ensuremath{-}}$ excited state in $^{14}\mathrm{B}$. The experimental data are compared to the results of shell-model calculations.

This paper describes the implementation and commissioning of a device based on a new concept for measurements of nuclear reactions in inverse kinematics. The HELIcal Orbit Spectrometer, HELIOS, was commissioned at Argonne National Laboratory by studying the 28Si(d,p)29Si reaction in inverse kinematics. This experiment served as a proof of principle for this previously untested concept, and was used to verify the response and performance characteristics of HELIOS.

Isoscaling studies of fragments with Z = 1 – 8 from reconstructed quasiprojectiles of mass A ≃ 40 from the Ar 40 + Sn 124 , 112Sn and Ca 40 + Sn 124 , 112Sn reactions at beam energy of 45 MeV/nucleon were performed. After initial efforts to obtain isoscaling with the “traditional” approach of using pairs of systems differing in their isospin asymmetry (or neutron-to-proton ratio N / Z ), “intra-system” isoscaling for each of these four systems was obtained using fragment sources restricted in two narrow N / Z regions (one neutron-rich and one neutron-poor). The observed isoscaling behavior was excellent and the isoscaling parameter α was found to decrease with increasing excitation energy. Corrections due to undetected neutrons were also taken into account in the source N / Z determination by using the theoretical models DIT (Deep Inelastic Transfer) and SMM (Statistical Multifragmentation Model) along with a software replica of the experimental setup. These corrections were applied to the determination of the parameter Δ (expressing the difference in the isospin asymmetry of the two sources used in the isoscaling). The reduced isoscaling parameter α / Δ was obtained and found to decrease as the excitation energy of the quasiprojectile source increases, in good agreement with recent work on reconstructed mass A ≃ 80 quasiprojectiles. This decrease of α / Δ may point to a decrease of the symmetry energy coefficient with increasing excitation energy.

The near-term radioactive beam capabilities of ATLAS include radioactive beams produced in flight in a gas cell, or starting in the fall of 2009, re-accelerated beams of 252 Cf fission fragments provided by the new CARIBU injector. The availability of such exotic beams will allow for detailed studies of the single-particle aspects of nuclear structure in neutron-rich nuclei reaching out to the astrophysical r-process path by employing light-ion reactions in inverse kinematics. The HELIOS spectrometer is based on a new concept that is especially well suited for such studies. This concept was recently demonstrated using the reactions D (28 Si , p )29 Si with a (stable) 168 MeV 28 Si beam. Since then D (12 B , p )13 B , D (17 O , p )18 O , and D (15 C , p )16 C have been studied successfully. The combination of neutron-rich beams from CARIBU and the HELIOS spectrometer opens a fertile research area of precision studies of the single particle strengths and collective excitations in exotic nuclei, and is likely to have applications in other reactions as well.

The signal of isospin-asymmetric phase transition in the evolution of the chemical potential was observed for hot quasi-projectiles produced in the reactions 40,48Ca + 27Al confirming an analogous observation in the lighter system 28Si + 112,124Sn. With increasing mass, the properties of hot quasi-projectiles become increasingly influenced by the secondary emission. Thermodynamical observables exhibit no sensitivity to the different number of missing neutrons in the two reactions 40,48Ca + 27Al, thus providing a signal of dynamical emission of neutrons, which can be related to formation of a very neutron-rich low-density region (neck) between the projectile and target., Comment: LaTeX, article expanded, 2 figures added, 17 pages, 7 figures

A dual-axis dual-lateral position-sensitive detector has been developed for charged particle detection. This detector consists of a 20×20 mm square double-sided p-on-n silicon structure with a highly uniform resistive junction and ohmic layers with equi-potential channels. This detector was developed for the possible integration into the FAUST array. In-beam experimental results reveal a detector position resolution better than 200 μm with a non-linearity of 0.002% (rms). The energy resolution as determined from a 228Th alpha source is ∼80 keV for the 6.778 MeV alpha.

The upgraded NIMROD–ISiS 4 π detector array is described. The array is composed of 228 detector modules annularly arranged into 14 rings. Telescopes of Si–CsI and Si–Si–CsI provide excellent isotopic resolution throughout the detector array. To enhance event characterization, the entire charged particle array is housed inside the TAMU Neutron Ball.

The production and separation of neutron-rich rare isotope beams in peripheral collisions around the Fermi energy is described in the present work. The experiments were performed at the Cyclotron Institute of Texas A&M University employing beams from the K500 Superconducting Cyclotron. Two magnetic separators were used: the MARS recoil separator and the Superconducting Solenoid Line (BigSol Line). Enhanced production cross sections of neutron-rich nuclides in comparison with high-energy fragmentation mechanisms were observed and attributed to the role of the N/Z and the nuclear periphery of the target. From a practical viewpoint, these reactions below or around the Fermi energy offer a promising way to access very neutron-rich rare isotopes. The experience obtained in the production of rare isotope beams (RIB) in this energy range will be applied in the ongoing RIB upgrade of the Cyclotron Institute that will involve production, stopping and re-acceleration of rare isotopes.

An overview of recent efforts to produce and separate neutron-rich rare isotopes in quasielastic and deep-inelastic collisions around and below the Fermi energy is presented. The experiments have been performed at the Cyclotron Institute of Texas A&M University employing beams from the K500 Superconducting Cyclotron. Two magnetic separators were used: the MARS recoil separator and the Superconducting Solenoid Line (BigSol Line). In these efforts we observed an enhanced production of neutron-rich nuclides in comparison with high-energy fragmentation mechanisms. This trend has been attributed to the role of the N/Z ratio and the nuclear periphery of the target. From a practical viewpoint, we conclude that reactions below or around the Fermi energy offer a novel way to access very neutron-rich rare isotopes. The experience obtained in the production of rare isotope beams (RIB) below the Fermi energy will be exploited in the ongoing RIB Upgrade of the Cyclotron Institute that will involve production, stopping and reacceleration of rare isotopes.

The process of nuclear multifragmentation leads to thermodynamic conditions akin to those encountered in the collapse/explosion of massive stars. Thus, the knowledge obtained from studying multifragmentation may be applied to describe matter distribution in supernova. Along these lines, the present study focuses on the symmetry energy of hot fragments produced in the multifragmentation of neutron-rich systems following collisions near the Fermi energy. The experiments consist of high-resolution mass spectrometric measurements of the isotopic and velocity distributions of heavy projectile fragments. The data were systematically compared to calculations with the Statistical Multifragmentation Model (SMM). The study indicates a gradual decrease of the symmetry energy coefficient from the standard value of ∼25 MeV in the compound nucleus regime ( E ∗ / A E ∗ / A > 4 MeV). The isotopic distributions of the hot fragments are very wide and extend towards or beyond the neutron drip-line. These findings may have important implications to the composition and evolution of hot astrophysical environments, such as core-collapse supernova and the course of the ensuing nucleosynthesis processes, such as the r-process.

The sequential breakup of $E/A=65.5\text{-MeV}\phantom{\rule{4pt}{0ex}}^{7}\mathrm{Be}$ and $E/A=36.6\text{-MeV}\phantom{\rule{4pt}{0ex}}^{6}\mathrm{Li}$ projectiles excited through inelastic interactions with $^{9}\mathrm{Be}$ target nuclei has been studied. For events where the target nucleus remained in its ground state, significant alignment of the excited projectile's spin axis parallel or antiparallel to the beam direction was observed. This unusual spin alignment was found to be largely independent of the projectile's scattering angle and it was deduced that the target nucleus has a significant probability of changing its spin orientation during the interaction. It is proposed that the unusual spin alignment is a consequence of the molecular structure of the $^{9}\mathrm{Be}$ nucleus.

The $(d,\ensuremath{\alpha})$ reaction is highly selective, favoring final states in which the removed neutron and proton are completely aligned in a $J=2j$ configuration. We have studied the $^{14,15}\mathrm{C}(d,\ensuremath{\alpha})^{12,13}\mathrm{B}$ reactions in inverse kinematics using the Helical Orbit Spectrometer (HELIOS) at Argonne National Laboratory. In $^{12}\mathrm{B}$, the reaction strongly favors the population of a known ${3}^{+}$ state at 5.61 MeV, and for $^{13}\mathrm{B}$, we observe a possible unreported doublet of states at high excitation energy, probably corresponding to the $^{12}\mathrm{B}({3}^{+})$ state coupled to the $1{s}_{1/2}$ neutron from the $^{15}\mathrm{C}$ ground state. In contrast to single-nucleon transfer, deuteron-transfer reactions have not been widely studied with exotic nuclei.

The design, construction, and performance of a new highly segmented charged particle detector array, FIRST, are described. This forward angle annular array ( 2 ∘ ⩽ θ lab ⩽ 28 ∘ ) has been developed to study peripheral and mid-central heavy-ion collisions at intermediate energies ( E / A ≈ 50 MeV ). FIRST consists of three individual telescopes that each utilize ion-passivated silicon detectors in either a Si(IP)–Si(IP)–CsI(Tl) stack or a Si(IP)–CsI(Tl) stack. This array provides elemental identification for 1 ⩽ Z ⩽ 50 with isotopic identification of lighter elements, Z ⩽ 13 , over a wide dynamic range in energy. The high segmentation of each silicon detector provides good angular resolution in a compact geometry and allows deconvolution of multiple particles incident on a single telescope. The performance of the array in a commissioning experiment Zn 64 + Zn 64 , Bi 209 at E / A = 45 MeV is shown.

The production of neutron-rich projectile residues in deep-inelastic collisions at Fermi energies and the scaling of their yields are investigated in this work. A large enhancement in the production of neutron-rich fragments was observed in the reactions of a 25 MeV/nucleon 86Kr beam with the neutron rich 64Ni and 124Sn targets. Simulations using a deep-inelastic transfer (DIT) code indicate that the neutron skins of the neutron-rich targets play an important role. From a practical viewpoint, such reactions may offer a novel way to access very neutron-rich rare isotopes. In parallel to the production studies, the scaling properties of the residue yields are investigated. An approach to study the process of N/Z equilibration has been developed based on residue yield ratios. This approach may provide a valuable tool of isospin studies with radioactive beams.

Light charged particle (LCP) emission in the evaporation residue (ER) and fusion fission (FF) channels have been studied for the 200 MeV 32S + 100Mo reaction, leading to 132Ce composite nuclei at E x =122 MeV. The main goal was to study the decay of 132 Ce on the basis of an extended set of observables, to get insights on the fission dynamics. The proton and alpha particle energy spectra, their multiplicities, ER-LCP angular correlations, ER and FF angular distributions, and ER and FF cross-sections were measured. The measured observables were compared with the Statistical Model (SM). Using standard parameters, the model was able to reproduce only the pre-scission multiplicities and the FF and ER cross-sections. The calculation was observed to strongly overestimate the proton and alpha particle multiplicities in the ER channel. Disagreements were also observed for the ER-LCP correlations, the LCP energy spectra and the ER angular distribution. By varying the SM input parameters over a wide range of values, it is shown that it is not possible to reproduce all the observables simultaneously with a unique set of parameters. The inadequacy of the model in reproducing the ER particle multiplicities is also observed analysing data from the literature for other systems in the A ≈ 150 and E x ≈ 100−200 MeV region. These results indicate serious limitations about the use of the SM in extracting information on fission dynamics.

Study of heavy ion induced fusion-fission reactions at near and below barrier energies has attracted a great deal of attention in recent years, due to the observations of anomalous features in the fragment angular distributions for many target-projectile systems. Additionally there are also measurements of the fragment spin distributions and time-scales of the fusion-fission reactions, which have provided important information on the dynamics of these processes. In the present paper, the emphasis would be to highlight some of the recent experimental findings and their implications on the dynamics of the fusion-fission reactions in heavy ion collisions at near and above barrier energies.

Measurement on fragment spin as a function of its mass has been carried out over a wide range of bombarding energy in 12 C, 16 O + 209 Bi and 12 C, 16 O + 232 Th reactions. The mass dependence of fragment spin for 12 C, 16 O + 232 Th reactions is observed to be in marked contrast to that for the 12 C, 16 O + 209 Bi reactions. The present results have been analysed within the statistical model by taking into account the finite relaxation time for the equilibration of the collective spin modes. It is found that the observed feature in 12 C, 16 O + 232 Th reactions are characteristic of incomplete equilibration of the collective spin modes where the mass relaxation process at extreme mass asymmetry terminates before full statistical equilibration of the collective spin modes are reached.

Recent efforts to produce and separate neutron-rich rare isotopes in peripheral collisions below the Fermi energy are presented. The experiments have been performed at the Cyclotron Institute of Texas A&M University employing beams from the K500 Superconducting Cyclotron. Two magnetic separators were used: the MARS recoil separator and the Superconducting Solenoid Line (BigSol Line). An enhanced production of neutron-rich nuclides in comparison with high-energy fragmentation mechanisms has been observed and attributed to the role of the N/Z and the nuclear periphery of the target. From a practical viewpoint, these reactions below or around the Fermi energy offer a novel way to access very neutron-rich rare isotopes. The experience obtained in the production of rare isotope beams (RIB) below the Fermi energy will be exploited in the ongoing RIB upgrade of the Cyclotron Institute that will involve production, stopping and reacceleration of rare isotopes.

The density dependence of the symmetry energy in the equation of state of asymmetric nuclear matter (N/Z $>$ 1) is important for understanding the structure of systems as diverse as the atomic nuclei and neutron stars. Due to a proper lack of understanding of the basic nucleon-nucleon interaction for matters that are highly asymmetric and at non-normal nuclear density, this very important quantity has remained largely unconstrained. Recent studies using beams from the Cyclotron Institute of Texas A$&$M University, constraining the density dependence of the symmetry energy, is presented. A dependence of the form E$_{sym}(\rho)$ = C($\rho/\rho_{o})^{\gamma}$, where C = 31.6 MeV and $\gamma$ = 0.69, is obtained from the dynamical and statistical model analysis. Their implications to both astrophysical and nuclear physics studies are discussed., Comment: Invited talk, Proceedings of CAARI 2006, Forth Worth, Texas, Aug 20 -25, 2006

Pre-scission and post-scission multiplicities of neutrons and alpha particles have been simultaneously measured for the fission-like reactions of 340 MeV Si-28 on Th-232. Dynamical model calculations using HICOL code predict that about 90% of the observed events are of quasi-fission type while the remaining 10% are from compound nucleus fission decay. Moving source fits were carried out to the observed neutron and alpha particle spectra, measured at different angles with respect to the fragment directions. The pre-scission and post-scission neutron multiplicities are deduced to be 8.7+/-2.0 and 9.4+/-2.0, respectively. The corresponding multiplicity values for alpha particles are found to be 0.22+/-0.08 and 0.1+/-0.03. From the measured post-scission neutron multiplicity, it is inferred that about 65+/-20 MeV of the initial excitation energy remains at scission. This may be compared to the value of 85+/-30 MeV estimated from PACE2 statistical model calculations, adjusted to reproduce the measured pre-scission neutron multiplicity. From a comparison of the Statistical Model predictions with the measured pre-scission neutron multiplicity, the fission delay is estimated to be of 5(-3)(+7) X 10(-20) s which overlaps with the average duration of fission-like process from the contact to the scission point (2 x 10(-20) s) as determined from HICOL-based dynamical calculations. For the delay time deduced as above, the pre-scission alpha particle multiplicity calculated by the PACE2 code is about a factor two larger than the experimental one, demonstrating the difficulties in modelling the alpha particle emission from highly elongated shapes that characterize the fissioning system from the contact point to scission.

Measurements of fission fragment gamma ray multiplicity distributions were carried out at near and sub-barrier energies in {sup 12}C, {sup 16}O + {sup 232}Th reactions. The results were analyzed to determine the average values of the total fragment spin, which were used to deduce the average spin of the compound nucleus {l_angle}l{r_angle}{sub CN}. It is observed that {l_angle}l{r_angle}{sub CN} decreases smoothly with decreasing bombarding energy and saturates as the energy falls through the barrier, thereby resembling features analogous to those predicted by various fusion models. The present results do not indicate any anomalous feature in the {l_angle}l{r_angle}{sub CN} at the sub-barrier energies, which imply that the recently observed anomalous fragment anisotropies in these systems are not due to anomalous broadening of fusion l distributions but may result from the narrowing of K distribution in the fission process. {copyright} {ital 1997} {ital The American Physical Society}

We have used the ${}^{13}$B($d,p$)${}^{14}$B reaction in inverse kinematics to study the properties of states in ${}^{14}$B, the lightest particle-bound $N=9$ isotone. The spectroscopic information, including spins, parities, and spectroscopic factors for the states observed in ${}^{14}$B are used to deduce the wave functions for the low-lying negative parity $\ensuremath{\nu}(\mathit{sd})$ levels, as well as provide information about the evolution of the effective neutron $1{s}_{1/2}\ensuremath{-}0{d}_{5/2}$ single-particle energies. The data confirm that the ground and first-excited states are predominantly $s$ wave in character and are single-neutron halo states. The effective single-particle energies are found to match the trends set by other $N=9$ isotones.

Equilibration of N/Z in binary breakup of an excited and transiently deformed projectile-like fragment (PLF*), produced in peripheral collisions of 64Zn + 27Al, 64Zn, 209Bi at E/A = 45 MeV, is examined. The composition of emitted light fragments (3, 6 pages, 4 figures

The single-neutron properties of N = 51 nuclei have been studied with the ( d , p )and( α , 3 He) reactions, at beam energies of 15 and 50 MeV respectively, on 88 Sr, 90 Zr, and 92 Mo targets. The light reaction products were momentum analyzed using a conventional magnetic spectrometer. Additionally, the 2 H( 86 Kr ,p ) reaction was measured at a beam energy of 10 MeV / u, where outgoing light ions were analyzed using a helical-orbit spectrometer. Absolute cross sections and angular distributions corresponding to the population of different final states in the heavy product were obtained for each reaction. Spectroscopic factors were extracted and centroids of the single-particle strength were deduced. The observations appear consistent with calculations based on an evolution of single-particle structure driven by the nucleon-nucleon forces acting between valence protons and neutrons. ispartof: Physical Review C, Nuclear Physics vol:87 issue:1 status: published

The interaction of an E/A=70 - MeV 7Be beam with a Be target was used to populate levels in 6Be following neutron knockout reactions. The three-body decay of the ground and first excited states into the alpha+p+p exit channel were detected in the High Resolution Array. Precise three-body correlations extracted from the experimental data allowed us to obtain insight into the mechanism of the three-body democratic decay. The correlation data are in a good agreement with a three-cluster-model calculation and thus validate this theoretical approach over a broad energy range., 5 pages, 7 figures; Corrected typos

The production cross sections of projectilelike fragments from the interaction of 15 MeV/nucleon 86 Kr with 64 Ni and 58 Ni and with 124 Sn and 112 Sn were measured using a magnetic separator with emphasis on the neutron-rich isotopes. Neutron pickup isotopes (with up to six neutrons picked up from the target) were observed with large cross sections. Calculations involving the the deep-inelastic transfer model as well as the microscopic constrained molecular dynamics model (CoMD) for the primary interaction stage coupled to the statistical deexcitation code GEMINI were used to describe the gross properties of the product distributions. The present results were also compared with our previous data of the same reactions at 25 MeV/nucleon. The data at 15 MeV/nucleon show enhanced production of neutron-rich isotopes very close to the projectile, relative to the corresponding data at 25 MeV/nucleon. This enhancement in the cross sections is possibly associated with very peripheral collisions and longer interaction times of the neutron-rich 86 Kr projectile with the neutron-rich targets. The large cross sections of such reactions well above the Coulomb barrier, but below the Fermi energy, involving peripheral nucleon exchange, suggest that both the N /Z of the projectile and the N /Z of the target may properly be exploited in the production of neutron-rich rare isotopes. These reactions offer a novel and attractive route to access extremely neutron-rich rare isotopes toward the the astrophysical r-process path and, possibly, the neutron drip-line.

Deviations from the isobaric multiplet mass equation are presented and discussed for the $A=7$, $T=3/2$ quartet and the $A=8$, $T=2$ quintet.

The single-neutron properties of the $N=83$ nucleus ${}^{137}$Xe have been studied using the ${}^{136}$Xe($d$,$p$) reaction in inverse kinematics at a beam energy of 10 MeV/u. The helical-orbit spectrometer, HELIOS, at Argonne National Laboratory was used to analyze the outgoing protons, achieving an excitation-energy resolution of \ensuremath{\sim}100 keV. Extraction of absolute cross sections, angular distributions, and spectroscopic factors has led to a more complete understanding of the single-neutron strength in ${}^{137}$Xe. In particular, the centroids of the $\ensuremath{\nu}{h}_{9/2}$ and $\ensuremath{\nu}{i}_{13/2}$ strengths appear to evolve through the $N=83$ isotones in a manner consistent with the action of the tensor force.

The interactions of an E/A=70-MeV {sup 9}C beam with a Be target was used to populate levels in Be, B, and C isotopes, which undergo decay into many-particle exit channels. The decay products were detected in the HiRA array and the level energies were identified from their invariant mass. Correlations between the decay products were examined to deduce the nature of the decays, specifically to what extent all the fragments were created in one prompt step or whether the disintegration proceeded in a sequential fashion through long-lived intermediate states. In the latter case, information on the spin of the level was also obtained. Of particular interest is the five-body decay of the {sup 8}C ground state, which was found to disintegrate in two steps of two-proton decay passing through the {sup 6}Be{sub g.s.} intermediate state. The isobaric analog of {sup 8}C{sub g.s.} in {sup 8}B was also found to undergo two-proton decay to the isobaric analog of {sup 6}Be{sub g.s.} in {sup 6}Li. A 9.69-MeV state in {sup 10}C was found to undergo prompt four-body decay to the 2p + 2{alpha} exit channel. The two protons were found to have a strong enhancement in the diproton region and the relativemore » energies of all four p-{alpha} pairs were consistent with the {sup 5}Li{sub g.s.} resonance.« less

The transverse flow and relative midrapidity yield of isotopically identified light charged particles (LCPs) has been examined for the 35 MeV/nucleon ${}^{70}\mathrm{Zn}+{}^{70}\mathrm{Zn}$, ${}^{64}\mathrm{Zn}+{}^{64}\mathrm{Zn}$, and ${}^{64}\mathrm{Ni}+{}^{64}\mathrm{Ni}$ systems. A large enhancement of the midrapidity yield of the LCPs was observed relative to the yield near the projectile rapidity. In particular, this enhancement was increased for the more neutron-rich LCPs demonstrating a preference for the production of neutron-rich fragments in the midrapidity region. Additionally, the transverse flow of the LCPs was extracted, which provides insight into the average movement of the particles in the midrapidity region. Isotopic and isobaric effects were observed in the transverse flow of the fragments. In both cases, the transverse flow was shown to decrease with an increasing neutron content in the fragments. A clear inverse relationship between the transverse flow and the relative midrapidity yield is shown. The increased relative midrapidity emission produces a decreased transverse flow. The stochastic mean-field model was used for comparison to the experimental data. The results showed that the model was able to reproduce the general isotopic and isobaric trends for the midrapidity emission and transverse flow. The sensitivity of these observables to the density dependence of the symmetry energy was explored. The results indicate that the transverse flow and midrapidity emission of the LCPs are sensitive to the denisty dependence of the symmetry energy.

The transverse flow of intermediate mass fragments (IMFs) has been investigated for the 35 MeV/u ${}^{70}\mathrm{Zn}+{}^{70}\mathrm{Zn}$, ${}^{64}\mathrm{Zn}+{}^{64}\mathrm{Zn}$, and ${}^{64}\mathrm{Ni}+{}^{64}\mathrm{Ni}$ systems. A transition from the IMF transverse flow strongly depending on the mass of the system, in the most violent collisions, to a dependence on the charge of the system, for the peripheral reactions, is shown. This transition was shown to be sensitive to the density dependence of the symmetry energy using the antisymmetrized molecular-dynamics model. The results present an observable, the IMF transverse flow, that can be used to probe the nuclear equation of state. Comparison with the simulation demonstrated a preference for a stiff density dependence of the symmetry energy.

$^{8}\mathrm{C}$ is found to decay to four protons and an $\ensuremath{\alpha}$ particle in two $2p$ emission steps. The correlations between the protons in the first step ($^{8}\mathrm{C}$ to $^{6}\mathrm{Be}$) exhibit a significant enhancement in the region of the decay phase space where the two protons have small relative energy, a region sometimes called the diproton region. The decay of the isobaric analog of $^{8}\mathrm{C}$ in $^{8}\mathrm{B}$ is also found to decay by $2p$ emission. This is the first case of isospin-allowed $2p$ decay between isobaric analog states.

The critical phenomenon of the liquid-gas phase transition has been investigated in the reactions $^{78,86}\mathrm{Kr}$$+$$^{58,64}\mathrm{Ni}$ at beam energy of 35 MeV/nucleon using the Landau free energy approach with isospin asymmetry as an order parameter. Fits to the free energy of fragments showed three minima, suggesting that the system is in the regime of a first-order phase transition. The relation m $=$ \ensuremath{-}\ensuremath{\partial}F/\ensuremath{\partial}H, which defines the order parameter and its conjugate field $H$, has been experimentally verified from the linear dependence of the mirror nuclei yield ratio data on the isospin asymmetry of the source. The slope parameter, which is a measure of the distance from a critical temperature, showed a systematic decrease with increasing excitation energy of the source. Within the framework of the Landau free energy approach, isoscaling provided similar results as obtained from the analysis of mirror nuclei yield ratio data. In the present work, it is shown that the external field is primarily related to the minimum of the free energy, which implies a modification of the source concentration \ensuremath{\Delta} used in isospin studies.

We have studied the $^{15}\mathrm{C}(d,p)^{16}\mathrm{C}$ reaction in inverse kinematics using the Helical Orbit Spectrometer at Argonne National Laboratory. Prior studies of electromagnetic-transition rates in $^{16}\mathrm{C}$ suggested an exotic decoupling of the valence neutrons from the core in that nucleus. Neutron-adding spectroscopic factors give a different probe of the wave functions of the relevant states in $^{16}\mathrm{C}$. Shell-model calculations reproduce both the present transfer data and the previously measured transition rates, suggesting that $^{16}\mathrm{C}$ may be described without invoking very exotic phenomena.

We have studied the ¹⁵C(d,p)¹⁶C reaction in inverse kinematics using the Helical Orbit Spectrometer at Argonne National Laboratory. Prior studies of electromagnetic-transition rates in ¹⁶C suggested an exotic decoupling of the valence neutrons from the core in that nucleus. Neutron-adding spectroscopic factors give a different probe of the wave functions of the relevant states in ¹⁶C. Shell-model calculations reproduce both the present transfer data and the previously measured transition rates, suggesting that ¹⁶C may be described without invoking very exotic phenomena.

Peripheral collisions of $^{40}\mathrm{Ca}$ and $^{48}\mathrm{Ca}$ projectiles at 32 MeV/nucleon on $^{112}\mathrm{Sn}$ and $^{124}\mathrm{Sn}$ targets were studied in this work. The fragments of the projectile-like source (quasiprojectile) were collected with a charged-particle multidetector array. The average value of the neutron-to-proton ratio $N/Z$ of the quasiprojectiles formed in the reactions was determined with two approaches. The first is a direct reconstruction approach using isotopically resolved fragments and is hindered by undetected neutrons leading to lower $N/Z$ values. The second approach, based on the assumption of early fragment formation, employs yield ratios of fragment isobars and is not hindered by undetected neutrons. Using this approach, the amount of $N/Z$ mixing that occurred in the quasiprojectiles (compared to a fully $N/Z$ equilibrated system) was found to be approximately $53%$. The experimental results were compared with model calculations. First, the phenomenological DIT (deep inelastic transfer) model was used, followed by the statistical multifragmentation model (SMM). The results of these calculations are in close agreement with the data and indicate that the mean number of undetected neutrons increases with the $N/Z$ of the composite system, accounting for the difference observed between the two approaches of quasiprojectile $N/Z$ determination. Second, the microscopic transport model IBUU (isospin-dependent Boltzmann-Uehling-Uhlenbeck) was employed, providing preliminary results in reasonable agreement with the data. The determination of the degree of $N/Z$ equilibration employing the present fragment yield ratio approach may provide a valuable probe to study the isospin part of the nuclear equation of state in conjunction with detailed microscopic models of the collisions in the Fermi energy regime.

A first experiment is reported that makes use of a new kind of spectrometer uniquely suited to the study of reactions with radioactive beams in inverse kinematics, the helical orbit spectrometer, HELIOS. The properties of some low-lying states in the neutron-rich $N=8$ nucleus $^{13}\mathrm{B}$ were studied with good resolution. From the measured angular distributions of the $(d,\text{\hskip-0.22em}p)$ reaction and the relative spectroscopic factors, spin and configuration assignments of the first- and third-excited states of this nucleus can be constrained.

The nuclear symmetry energy is a fundamental quantity important for studying the structure of systems as diverse as the atomic nucleus and the neutron star. Considerable efforts are being made to experimentally extract the symmetry energy and its dependence on nuclear density and temperature. In this article, we review experimental studies carried out up-to-date and their current status., Comment: 10 pages, 3 figures, talk presented at the International Symposium in Nuclear Physics, Mumbai, India, Dec. 2009. Added few more references. Minor correction in Reference

A new thermometer based on fragment momentum fluctuations is presented. This thermometer exhibited residual contamination from the collective motion of the fragments along the beam axis. For this reason, the transverse direction has been explored. Additionally, a mass dependence was observed for this thermometer. This mass dependence may be the result of the Fermi momentum of nucleons or the different properties of the fragments (binding energy, spin, etc.) which might be more sensitive to different densities and temperatures of the exploding fragments. We expect some of these aspects to be smaller for protons (and/or neutrons); consequently, the proton transverse momentum fluctuations were used to investigate the temperature dependence of the source.

In heavy-ion collisions, isoscaling provides a method for studying the evolution of nuclear symmetry energy as a function of excitation energy. One challenge in using isoscaling is to accurately determine the neutron-to-proton ratio ($N/Z$) of the fragmenting source. Isoscaling results are presented for the reactions of $^{86,78}\mathrm{Kr}+^{64,58}\mathrm{Ni}$ at 35 MeV/nucleon taken on the NIMROD-ISiS array at Texas A University. The $N/Z$ of the source was calculated from the isotopically identified fragments and experimentally measured neutrons emitted from reconstructed quasiprojectiles. These data exhibit isoscaling for elements with $Z=1\text{\ensuremath{-}}17$ over a broad range of isotopes. The isoscaling parameter $\ensuremath{\alpha}$ is shown to increase with increasing difference in the neutron composition (\ensuremath{\Delta}) of the compared sources. For a selected \ensuremath{\Delta}, the ratio $\ensuremath{\alpha}$/\ensuremath{\Delta} is also shown to decrease with increasing excitation energy. This may reflect a corresponding decrease in the nuclear symmetry energy.

Current advances in technology have enabled dramatic improvements to the performance of multi‐detector arrays within the last 10 years. FAUST is a forward array of 68 Si‐CsI(Tl) detector telescopes that has been in use since 1996. To take full advantage of current technology, FAUST has undergone an overhaul installing new preamplifiers from Zepto Systems and modifications to allow for Dual‐Axis Dual‐Lateral position sensitive detectors to be installed. A new calibration software package has also been developed utilizing a novel linearization algorithm. The combination of these upgrades has led to isotopic identification for elements in the Z = 1–13 range and has greatly increased the angular resolution of the array.

In this work, the isoscaling for the 40Ca+112,124Sn reactions at the beam energy of 45 MeV/A was investigated as a function of the excitation energy of reconstructed quasi‐projectiles. The excitation energy dependence of the isoscaling parameter obtained from the intra‐system isoscaling was investigated and is expected to provide information for the determination of the symmetry energy coefficient of highly excited nuclei.

Assuming a schematic form of the nucleon effective mass as a function of nuclear excitation energy and mass, we provide a simple explanation for understanding the experimentally observed mass dependence of the nuclear caloric curve. It is observed that the excitation energy at which the caloric curve enters into a plateau region, could be sensitive to the nuclear mass evolution of the effective nucleon mass., Comment: 5 pages, 5 figures, Accepted for publication in Phys. Rev. C. Minor changes made

The decrease in the symmetry energy of hot nuclei populated in $^{58}$Ni + $^{58}$Ni, $^{58}$Fe + $^{58}$Ni and $^{58}$Fe + $^{58}$Fe reactions at beam energies of 30, 40, and 47 MeV/nucleon, as a function of excitation energy is studied. It is observed that this decrease is mainly a consequence of increasing expansion or decreasing density rather than the increasing temperature. The results are in good agreement with the recently reported microscopic calculation based on the Thomas-Fermi approach. An empirical relation to study the symmetry energy of finite nuclei in various mass region is proposed., Comment: 10 pages, 2 figures

The density dependence of the symmetry energy in the equation of state of isospin asymmetric nuclear matter is of significant importance for studying the structure of systems as diverse as the neutron-rich nuclei and the neutron stars. A number of reactions using the dynamical and the statistical models of multifragmentation, and the experimental isoscaling observable, is studied to extract information on the density dependence of the symmetry energy. It is observed that the dynamical and the statistical model calculations give consistent results assuming the sequential decay effect in dynamical model to be small. A comparison with several other independent studies is also made to obtain important constraint on the form of the density dependence of the symmetry energy. The comparison rules out an extremely " stiff " and " soft " form of the density dependence of the symmetry energy with important implications for astrophysical and nuclear physics studies., 16 pages, 14 figures