We present the results of the first commissioning phase of the short-focal-length area of the Apollon laser facility (located in Saclay, France), which was performed with the first available laser beam (F2), scaled to a nominal power of 1 PW. Under the conditions that were tested, this beam delivered on-target pulses of 10 J average energy and 24 fs duration. Several diagnostics were fielded to assess the performance of the facility. The on-target focal spot and its spatial stability, the temporal intensity profile prior to the main pulse, and the resulting density gradient formed at the irradiated side of solid targets have been thoroughly characterized, with the goal of helping users design future experiments. Emissions of energetic electrons, ions, and electromagnetic radiation were recorded, showing good laser-to-target coupling efficiency and an overall performance comparable to that of similar international facilities. This will be followed in 2022 by a further commissioning stage at the multi-petawatt level.
The new facility, Extreme Light Infrastructure – Nuclear
Physics (ELI-NP), is a combined laser-gamma nuclear physics research
facility currently undergoing its final implementation stages in
Măgurele near Bucharest, Romania. It already hosts two
fully-operational 10 PW laser arms and, by 2023, it will also house
a γ-beam system based on laser Compton backscattering,
capable of delivering a high-brilliance, low-energy beam at
E
γ ≲ 19.5 MeV. Owing to this unique laser-gamma
instrumentation combination, several types of experiments will be
possible at ELI-NP, including high precision nuclear resonance
fluorescence (NRF) experiments. In this case, the main γ-beam
detection system for performing NRF studies at ELI-NP is represented
by the ELI Array of DEtectors (ELIADE), featuring eight high-purity
germanium (HPGe) segmented clover detectors. The current work
presents the characteristics of two of the ELIADE detectors,
including their photopeak detection efficiency, energy resolution,
and peak-to-total ratio measured using γ-ray sources, as well
as the timing performance obtained via in-beam measurements. For
these latter detector tests, 130La was populated via the fusion
evaporation reaction 121Sb(12C,3n)130La using a beam
energy of 53 MeV at the Horia Hulubei National Institute of Physics
and Nuclear Engineering (IFIN-HH), also located in
Măgurele. Herein, we report on the results of the ^130La
linear polarization measurements taken using the ELIADE detectors as
Compton polarimeters. The results obtained from the in-beam
experiment were compared to several already published works and we
present new information on the transition multipolarity in
130La.
Background: Nuclear structure information for the neutron-rich actinide nuclei is important since it is the benchmark for theoretical models that provide predictions for the heaviest nuclei. Purpose: γ -ray spectroscopy of neutron-rich heavy nuclei in the actinide region. Method: Multinucleon-transfer reactions in 70 Zn + 238 U and 136 Xe + 238 U have been measured in two experiments performed at the INFN Legnaro, Italy. In the 70 Zn experiment the high-resolution HPGe Clover Array (CLARA) coupled to the magnetic spectrometer PRISMA was employed. In the 136 Xe experiment the high-resolution Advanced Gamma Tracking Array (AGATA) was used in combination with PRISMA and the Detector Array for Multinucleon Transfer Ejectiles (DANTE). Results: The ground-state band (g.s. band) of 240 U was measured up to the 20 + level and a tentative assignment was made up to the (24 + ) level. Results from γ γ coincidence and from particle coincidence analyses are shown. Moments of inertia (MoI) show a clear upbend. Evidence for an extended first negative-parity band of 240 U is found. Conclusions: A detailed comparison with latest calculations shows best agreement with cranked relativistic Hartree-Bogoliubov (CRHB) calculations for the g.s. band properties. The negative-parity band shows the characteristics of a K π = 0 − band based on an octupole vibration.
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