Speaker
Giovanni Luca Guardo
(LNS)
Description
The Extreme Light Infrastructure-Nuclear Physics (ELI-NP) facility, under construction in
Magurele near Bucharest in Romania, will provide high-intensity and high-resolution gamma
ray beams that can be used to address hotly debated problems in nuclear astrophysics, such as
the accurate measurements of the cross sections of the 24Mg(
,)20Ne reaction, that is funda-
mental to determine the effective rate of 28Si destruction right before the core collapse and the
subsequent supernova explosion [1], and other photo-dissociation processes relevant to stellar
evolution and nucleosynthesis [2].
For this purpose, a silicon strip detector array (named ELISSA, acronym for Extreme Light In-
frastructure Silicon Strip Array) will be realized in a common effort by ELI-NP and INFN-LNS
(Catania, Italy), in order to measure excitation functions and angular distributions over a wide
energy and angular range. According to our simulations, the final design of ELISSA will be a
very compact barrel configuration, leaving open the possibility in the future to pair a neutron
detector with the array. The kinematical identification will allow to separate the reaction of
interest from others thanks to the good expected angular and energy resolutions.
A prototype of ELISSA was built and tested at Laboratori Nazionali del Sud (INFN-LNS) in
Catania with the support of ELI-NP. In this occasion, we have carried out experiments with
alpha sources and with a 11 MeV 7Li beam. We used X3 and QQQ3 silicon-strip position sen-
sitive detectors manufactured by Micron Semiconductor ltd. Thanks to our approach, the first
results of those tests show up a very good energy resolution (better than 1%) and very good
position resolution, of the order of 1 mm. At very low energies, below 1 MeV, a worse position
resolution is found, of the order of 5 mm, but still good enough for the measurement of angular
distribution and the kinematical identification of the reactions induced on the target by gamma
beams. Moreover, a threshold of 150 keV can be easily achieved with no cooling. We will discuss
technical details of the detector and present results regarding Monte Carlo simulation, energy
resolution and detection thresholds of ELISSA, the physical cases to be investigated.
To sum up, these tests allow us to say that the X3 detectors, as well the standard QQQ3 detec-
tors, are perfectly suited for nuclear astrophysics studies with ELISSA. In particular, ELISSA
will allow us to determine a much more accurate cross section for the 24Mg photodissociation to
be used in nuclear reaction network calculations to improve the knowledge of the pre-supernova
chemical composition.
Primary author
Giovanni Luca Guardo
(LNS)
