The Array for Nuclear Astrophysics Studies with Exotic Nuclei (ANASEN)*

Abstract

Reactions involving radioactive nuclei play an important role in stellar explosions, but experimental information about most reactions involving short-lived nuclei is limited. New facilities aim to provide wider access to unstable isotopes, but the limited intensities that are available require more efficient and selective techniques and devices to study the reactions important for astrophysics. The Array for Nuclear Astrophysics Studies with Exotic Nuclei (ANASEN) is a charged-particle detector array designed primarily for studies of reactions important in the αp-and rp-processes with proton-rich exotic nuclei. The array consists of 40 silicon-strip detectors backed with CsI scintillators. The detectors cover an area of about 1300 cm 2 providing essentially complete solid angle coverage for the reactions of interest with good energy and position resolution. ANASEN also includes a position-sensitive annular gas proportional counter that allows it to be used as an active gas target/detector. One of the primary goals of ANASEN is the direct measurement of (α,p) reactions in inverse kinematics. ANASEN is also well suited for studies of proton elastic and inelastic scattering, (p,α) reactions and transfer reactions, which will also be studied to indirectly determine reaction rates important for astrophysics. The array is being developed by Louisiana State University and Florida State University, and will be used primarily at the RESOLUT radioactive ion beam facility at FSU and the ReA3 facility at the National Superconducting Cyclotron Laboratory.

Characterization of X3 Silicon Detectors for the ELISSA Array at ELI-NP

“…The minimum and maximum energy resolution (FWHM) measured on the front side is of 37 keV-57 keV, depending on the specific detector. This is better than the previously published results of about 60 keV with an α-source for similar arrays using X3-type detectors and read-out chain with preamplifiers [6,8]. The results obtained on the rear side are worse, i.e.…”

“…The ELISSA array consisting of three rings of twelve single-sided X3 detectors, and two end-caps made up of four double-sided QQQ3 detectors from Micron Semiconductor [4] is under construction at the Extreme Light Infrastructure-Nuclear Physics (ELI-NP) facility in Magurele, Romania. This type of array has already been successfully applied for nuclear astrophysics studies, e g. ORRUBA (Oak Ridge Rutgers University Barrel Array) or ANASEN (Array for Nuclear Astrophysics Studies with Exotic Nuclei) [5,6].…”

Radioactive Ion Beam studies of αp process waiting points in X-Ray Bursts

“…Measurements in the astrophysically relevant energy regime are desirable, as well as direct measurements of the forward (α, p) reactions. As facilities continue to produce more intense RIBs, these measurements will become feasible and direct studies of these reaction rates using the new HELIcal Orbit Spectrometer (HELIOS) at AT-LAS [18] and the Array for Nuclear Astrophysical Studies with Exotic Nuclei (ANASEN) [19] are being explored. Measuring these and other key reaction rates, in addition to the other nuclear input that is needed for stellar modeling of XRBs, is crucial if we are to fully understand these astrophysical events.…”

Development of the ELISSA array: prototype testing at Laboratori Nazionali del Sud

“…Moreover, a silicon array would make it possible to measure reactions on solid targets with the possibility to measure excitation functions and angular distributions over a wide range allowing for a better understating of reaction mechanism. Resistive strip silicon detector arrays have been successfully designed and commissioned for studies of nuclear astrophysics reactions, e g. ORRUBA (Oak Ridge Rutgers University Barrel Array) or ANASEN (Array for Nuclear Astrophysics Studies with Exotic Nuclei) [5,6]. In the case of photonuclear reactions of astrophysical relevance, since photodissociations are induced at photon energies slightly larger than particle emission thresholds owing to the typical temperatures in stars, the emitted fragments have low energies, ranging from few hundreds keV to few MeV.…”