Ponente
Descripción
The international collaboration constituted based on the Total Absorption Gamma-ray
Spectroscopy technique (TAGS) in Europe is aiming to build a Total Absorption Spectrometer
(TAS) of the next generation. TAGS is a calorimetric technique using large monolithic or
segmented scintillators that cover more than 80% of 4p, but with limited energy resolution. It
complements high-resolution spectroscopy using Germanium crystals. It is particularly well
suited to physics themes requiring the detection of high-energy or multiple gamma photons,
as in the case of beta decay of short-lived nuclei, or the measurement of reaction cross
sections useful in certain nucleosynthesis processes. Indeed, in the case of beta decay of nuclei
with large Q-values, the excitation energy states of the daughter nucleus are located at high
energy and de-excited by multiple gamma lines or very energetic gamma-rays. A systematic
error known as the Pandemonium effect [1] can affect data due to the low intrinsic or
geometric efficiency of devices based on HPGe-type detectors. This effect results in poor
determination of beta intensity distributions, and has far-reaching consequences for topics
involving good knowledge of these intensity distributions.
The new instrument, called STARS (Segmented Total Absorption with higher Resolution
Spectrometer), will ally efficiency with a higher segmentation and energy resolution than the
existing spectrometers thanks to the addition of 16 LaBr3 crystals. The two segmented TAS
that exist in Europe that will benefit from this upgrade are DTAS detector (18 NaI crystals [2])
and the Rocinante detector (12 BaF2 crystals [3]). The scientific advances that will be made
possible will concern nuclear structure, nuclear astrophysics, neutrino and reactor physics,
topics to which the TAGS technique has proven to bring significant advances [4]. The research
objectives span a wide physics program.
The first experiment with the STARS is planned in GANIL in July. It will act at the time as a
commissioning of the advanced TAS that will be then be available for new nuclear data
measurements.
[1] J. C. Hardy et al., Phys. Lett. 71 B, 307 (1977).
[2] V. Guadilla et al., Nucl. Instr. Meth. A910, 79-89 (2018).
[3] E. Valencia et al., Phys. Rev. C 95, 024320 (2017).
[4] A. Algora, B. Rubio, J.-L. Tain, M. Fallot, W. Gelletly, Eur. Phys. J. A 57, 85 (2021) and
references therein.
