First direct measurement of 22^{22}Mg(α\alpha,p)25^{25}Al and implications for X-ray burst model-observation comparisons

Type-I X-ray burst (XRB) light curves are sensitive to the model's nuclear input and consequently affects the model-observation comparisons. $^{22}$Mg($\alpha$,p)$^{25}$Al is among the most important reactions which directly impact the XRB light curve. We report the first direct measurement of $^{22}$Mg($\alpha$,p)$^{25}$Al using the Active Target Time Projection Chamber. XRB light curve model-observation comparison for the source $\tt{GS 1826-24}$ using new reaction rate implies a less-compact neutron star than previously inferred. Additionally, our result removes an important uncertainty in XRB model calculations that previously hindered extraction of the neutron star compactness

Constraining the Neutron Star Compactness: Extraction of the 23Al(p,γ) Reaction Rate for the rp Process

The $^{23}$Al($p,\gamma$)$^{24}$Si reaction is among the most important reactions driving the energy generation in Type-I X-ray bursts. However, the present reaction-rate uncertainty limits constraints on neutron star properties that can be achieved with burst model-observation comparisons. Here, we present a novel technique for constraining this important reaction by combining the GRETINA array with the neutron detector LENDA coupled to the S800 spectrograph at the National Superconducting Cyclotron Laboratory. The $^{23}$Al($d,n$) reaction was used to populate the astrophysically important states in $^{24}$Si. This enables a measurement in complete kinematics for extracting all relevant inputs necessary to calculate the reaction rate. For the first time, a predicted close-lying doublet of a 2$_2^+$ and (4$_1^+$,0$_2^+$) state in $^{24}$Si was disentangled, finally resolving conflicting results from two previous measurements. Moreover, it was possible to extract spectroscopic factors using GRETINA and LENDA simultaneously. This new technique may be used to constrain other important reaction rates for various astrophysical scenarios

Constraining the rp-process by measuring 23

The 23Al(p, γ)24Si stellar reaction rate has a significant impact on the light-curve emitted in X-ray bursts. Theoretical calculations show that the reaction rate is mainly determined by the properties of direct capture as well as low-lying 2+ states and a possible 4+ state in 24Si. Currently, there is little experimental information on the properties of these states. In this proceeding we will present a new experimental study to investigate this reaction, using the surrogate reaction 23Al(d,n) at 47 AMeV at the National Superconducting Cyclotron Laboratory (NSCL). We will discuss our new experimental setup which allows us to use full kinematics employing the Gamma-Ray Energy Tracking In-beam Nuclear Array (GRETINA) to detect the γ-rays following the de-excitation of excited states of the reaction products and the Low Energy Neutron Detector Array (LENDA) to detect the recoiling neutrons. The S800 was used for identification of the 24Si recoils. As a proof of principle to show the feasibility of this concept the Q-value spectrum of 22Mg(d,n)23Al is reconstructed

Differential cross-section measurement of D(d,p) reaction, in energies and angles suitable for NRA

89 σ.Η εμφύτευση δευτερίου έχει χρησιμοποιηθεί εκτενώς στο παρελθόν με σκοπό την τροποποίηση των φυσικών ιδιοτήτων στα μέταλλα, τις ενώσεις και τους ημιαγωγούς. Ο ακριβής προσδιορισμός της κατανομής συγκέντρωσης δευτερίου, αποτελεί μια πρόκληση για όλες τις αναλυτικές τεχνικές της «ανάλυσης με δέσμη ιόντων» (IBA-Ion Beam Analysis). Η ανάλυση πυρηνικών αντιδράσεων (NRA - Nuclear Reaction Analysis) μέσω της αντίδρασης 2H(d,p) φαίνεται να είναι η πιο ελπιδοφόρα ειδικά για τις περιπτώσεις των πολυσύνθετων μητρών ή για την μελέτη των στρωμάτων εμφύτευσης σε μεγάλο βάθος, όπου η αντίδραση 2H(3He,p) και η τεχνική ανάλυσης με πυρήνες από ανάκρουση (ERDA - Elastic Recoil Detection Analysis) έχουν χρησιμοποιηθεί με επιτυχία αλλά κυρίως στην μελέτη υπέρλεπτων στρωμάτων δευτερίου, κοντά στην επιφάνεια του στόχου. Στην εργασία αυτή προσδιορίστηκαν οι διαφορικές ενεργές διατομές της αντίδρασης 2H(d,p) στις γωνίες 140, 150, 160 και 170 μοίρες, για E(d,lab)=900-1600 keV με βήμα ενέργειας 50 keV. Επιπλέον μετρήθηκαν ορισμένα σημεία σε τρεις ακόμη γωνίες μέχρι τις 110 μοίρες, με σκοπό την μελλοντική θεωρητική αξιολόγηση των αποτελεσμάτων.Deuteron implantation has been extensively used in the past as a means for the modification of the physical properties of metals, compounds and semiconductors. The accurate determination of the resulting deuteron depth profiles presents a series of problems for all the principal IBA (Ion Beam Analysis) techniques. Nuclear Reaction Analysis (NRA), using the 2H(d,p) reaction, seems to be the most promising candidate, especially in the case of complex matrices or for the study of deep-implanted layers, whereas the 2H(3He,p) reaction and ERDA (Elastic Recoil Detection Analysis) have been successfully employed in the past for the study of ultra-thin deuteron layers close to the target’s surface. In the present work differential cross-section values for the 2H(d,p) reaction have been determined at 140, 150, 160 and 170 (deg), for E(d,lab)=900-1600 keV, with an energy step of 50 keV. Selected data points were measured at three more backward detection angles, up to 110 (deg), in order to facilitate the subsequent theoretical evaluation.Παναγιώτης Ε. Γάστη

Determination and theoretical analysis of the differential cross sections of the ²H(d,p) reaction at energies and detection angles suitable for NRA (Nuclear Reaction Analysis)

The accurate determination of deuteron depth profile presents a strong analytical challenge for all the principal IBA (Ion Beam Analysis) techniques. As far as NRA (Nuclear Reaction Analysis) is concerned, the 2H(d,p) reaction, seems to be a promising candidate, especially in the case of complex matrices, or for the study of deep-implanted deuteron layers. In the present work differential cross-section values for the 2H(d,p) reaction have been determined at 140°, 160° and 170°, for Ed,lab=900-1600 keV, with an energy step of 50 keV, using a well-characterized, thin C:D target deposited on a polished Si wafer. The experimental results were analyzed using the R-matrix calculations code AZURE

Experimental study of

40K is one of the main isotopes responsible for the radiogenic heating of the mantle in Earth-like exoplanets [1] and hence, plays a very important role in the internal geophysical dynamics of a planet. The abundance of 40K in the mantle and the core of such planets is not always possible to be determined by astrophysical observations, although constraining the nuclear reaction rates of 40K during stellar evolution can also lead to constraining the present amount of 40K in these planets, which will improve our understanding on the habitability potential of Earth-like exoplanets. This study aims to constrain the 40K(n,α)37Cl reaction rate, one of the two major destruction paths of 40K in stellar nucleosynthesis,by measuring the reverse reaction 37Cl(α,n)40K and applying the principle of detailed balance as we have done before for the 40K (40K(n,p)40Ar reaction rate) [2]. During the first set of measurements we performed differential cross-section measurements of the 37Cl(α,n1γ)40K, 37Cl(α,n2γ)40K and 37Cl(α,n3γ)40K reaction channels, for six different center of mass energies in the range between 5.1 and 5.4 MeV. The experiment took place at the Edwards Accelerator Laboratory of Ohio University. The gamma rays from the reaction channels mentioned above were detected by two LaBr3 scintillators. Using the swinger facility to change the angle of the beam-target system with respect to the detection system, we were able to take measurements for the differential cross-section at six different angles between 20° and 120° in the lab system