First in-beam experiment with the ELIADE detectors: a spectroscopic study of 130La

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.

Lifetime measurements in $$^{182}\hbox {Pt}$$ using $$\gamma $$–$$\gamma $$ fast-timing

The level lifetimes of the $$2_1^+$$ 2 1 + and $$4_1^+$$ 4 1 + states in $$^{182}\hbox {Pt}$$ 182 Pt have been re-measured employing the $$\gamma $$ γ –$$\gamma $$ γ fast-timing technique using fast $$\hbox {LaBr}_3$$ LaBr 3 (Ce) scintillators. Excited states in the nucleus of interest were populated by the fusion-evaporation reaction $$^{170}\hbox {Yb}(^{16}\hbox {O},\hbox {4n})^{182}\hbox {Pt}$$ 170 Yb ( 16 O , 4n ) 182 Pt at a beam energy of 87 MeV provided by the FN Tandem accelerator of the University of Cologne. The lifetime of the $$2_1^+$$ 2 1 + state was re-measured with high accuracy to be $$\tau = 563(12)~$$ τ = 563 ( 12 ) ps and resolves inconsistencies from previous measurements. Experimental results are compared to theoretical calculations in the framework of the sd-IBM with and without configuration mixing.

Lifetimes of core-excited states in semi-magic $$^{95}\mathrm {Rh}$$

Lifetimes of negative-parity states have been determined in the neutron deficient semi-magic (N = 50) nucleus $$^{95}\mathrm {Rh}$$ 95 Rh . The fusion-evaporation reaction $$^{58}Ni(^{40}Ca, 3p)$$ 58 N i ( 40 C a , 3 p ) was used to populate high-spin states in $$^{95}\mathrm {Rh}$$ 95 Rh at the Grand Accélérateur National d’Ions Lourds (GANIL) accelerator facility. The results were obtained using the Doppler Shift Attenuation Method (DSAM) based on the Doppler broadened line shapes produced during the slowing down process of the residual nuclei in a thick $$6\;\mathrm {mg/cm}^2$$ 6 mg / cm 2 metallic target. B(M1) and B(E2) reduced transition strengths are compared with predictions from large-scale shell-model calculations.

The Dominance of Proton/Neutron Evaporation Exit-Channel in a Fusion-Evaporation Reaction: The Effect of Target Nuclear Ratio (N/Z)

Cross section of different evaporation residue have been calculated in 112Sn+16O (Neuron/Proton (N/Z) of the 112Sn target is 1.24) and124Sn+16O reaction (N/Z of the 124Sn is 1.48) with beam energy of 80 MeV using statistical model calculation code PACE4. These calculations predicts that the proton emission channels are predicted to be dominant when the N/Z ratio is small (i.e in the first reaction) whereas the neutron emission outgoing channels dominant in the second reaction when N/Z is large. Experimental phenomenon also revealed the fact that in order to populate the proton or neutron reach nucleus we have to choose the target material accordingly.

Exploring the structure of Xe isotopes in A ~ 130 region: Single particle and collective excitations

High and medium spin structures of 130,131Xe have been studied using α-induced fusion-evaporation reaction and the Indian National Gamma Array (INGA) coupled with a digital data acquisition system. Various new band structures and near yrast levels of 131Xe have been established. The multipolarities of the observed transitions have been assigned on the basis of the DCO ratios and the polarization asymmetry measurements. Band structures based on 1-quasi-particle (qp), 3-qp configurations have been observed. A new Magnetic Rotational (MR) band based on 5-qp configuration has also been established in 131Xe. The MR band has been interpreted in terms of shears mechanism with principal axis cranking (SPAC) calculations. Shell Model calculations are carried out to describe the non yrast states of 131Xe above the 11/2− isomer. New excited states have also been identified in 130Xe, produced in the same reaction.

Search for E(5) Symmetry in 102Pd

Lifetimes of the excited states in the yrast band of 102Pd have been deter- mined using the Recoil-Distance Doppler Shift experiment at INFN, Labo- ratori Nazionali di Legnaro. Excited states in 102Pd were populated by the 92Zr(13C,3n)102Pd fusion-evaporation reaction. Lifetimes were deduced using the Differential Decay Curve method and the corresponding B(E2) values were compared to the E(5) critical-point symmetry, and also the U(5) and O(6) limits of the Interacting Boson Model-1. It is evident that 102Pd agrees poorly with the predicted E(5) symmetry but has a very good (and somewhat surprising) agreement with the O(6) limit.

Study of neutron-deficient mercury isotopes Preliminary results on 189Hg

The mercury isotopic chain is depicted as one of the best fields to observe many phenomena related to collectivity evolution as, for instance, shape transition, shape coexistence or shape staggering. In this context, the 189Hg presents several interesting aspects and is still relatively unexplored. The nucleus has been studied at the Laboratori Nazionali di Legnaro using a fusion-evaporation reaction and the γ rays emitted have been detected by the GALILEO array, coupled with Neutron Wall and the GALILEO plunger. The presorting and the preliminary results are presented.

New Results on Excited States in the one-particle one-hole nucleus 56Co measured with MINIBALL detectors

The non-yrast states of the odd-odd nucleus 56Co have been investigated by studying the γ-rays induced in the predominantly fusion-evaporation reaction 56Fe(p,n γ)56Co at an incident energy of 10 MeV. The γ-rays were measured in-beam with four high-resolution MINIBALL-triple germanium (Ge) detectors. The experiment provided excellent data in γ-γ coincidences. The complex level scheme of 56Co was constructed mainly based on the analysis of these γ-γ coincidences. The angular distributions of the γ-rays were also analysed and allowed us to assign spin-parity values to most of the excited states in this nucleus. Despite the extensive work previously done studying the 56Co nucleus, the analysis presented in this work has resulted in a large improvement in the knowledge of its structure.