A brief outlook on low-energy nuclear physics is presented. Selected recent developments in nuclear structure theory are highlighted and a few open questions are discussed.

In order to understand the performance of the PARIS (Photon Array for the studies with Radioactive Ion and Stable beams) detector, detailed characterization of two individual phoswich (LaBr 3 (Ce)-NaI(Tl)) elements has been carried out. The detector response is investigated over a wide range of E γ = 0.6 to 22.6 MeV using radioactive sources and employing 11 B(p, γ) reaction at E p = 163 keV and E p = 7.2 MeV. The linearity of energy response of the LaBr 3 (Ce) detector is tested upto 22.6 MeV using three different voltage dividers. The data acquisition system using CAEN digitizers is set up and optimized to get the best energy and time resolution. The energy resolution of ∼ 2.1% at E γ = 22.6 MeV is measured for the configuration giving best linearity upto high energy. Time resolution of the phoswich detector is measured with a 60 Co source after implementing CFD algorithm for the digitized pulses and is found to be excellent (FWHM ∼ 315 ps). In order to study the effect of count rate on detectors, the centroid position and width of the E γ = 835 keV peak were measured upto 220 kHz count rate. The measured efficiency data with radioactive sources are in good agreement with GEANT4 based simulations. The total energy spectrum after the add-back of energy signals in phoswich components is also presented.

This paper presents an analytical model to quantify the measured noise in a cryogenic bolometer readout circuit. The model includes the contributions from the bias resistors and sensor resistors, voltage and current noise of amplifier, and cable capacitance. The model parameters are empirically estimated using frequency domain analysis of the measured noise data of indigenously developed Neutron Transmutation Doped (NTD) Ge sensors. The model is shown to describe noise data for NTD Ge sensors over a wide range of resistances corresponding to temperatures in the range 20–70 mK. Relative contributions of different components are discussed and it is shown that the contribution to the overall noise from the differential amplifier at 300 K is the dominant source. It is observed that the amplifier flicker noise is significantly lower than that specified in the amplifier datasheet. The present study also indicates that a desirable value of resistance of NTD sensor (R NTD) from noise considerations is ≲ 1 GΩ at ∼ 20 mK.

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Exclusive measurements of high energy γ-rays are performed in 124 Ba and 136 Ba at the same excitation energy (∼49 MeV), to study properties of the giant dipole resonance (GDR) over a wider N/Z range. The high energy γ-rays are measured in coincidence with the multiplicity of low energy γ-rays to disentangle the effect of temperature (T ) and angular momentum (J). The GDR parameters are extracted employing a simulated Monte Carlo statistical model analysis.The observed γ-ray spectra of 124 Ba can be explained with prolate deformation, whereas a single component Lorentzian function which corresponds to a spherical shape could explain the γ-ray spectra from 136 Ba. The observed GDR width in 136 Ba is narrower compared to that of 124 Ba.The statistical model best fit GDR cross sections are found to be in good agreement with the thermal shape fluctuation model (TSFM) calculations. Further, it is shown that the variation of GDR width with T is well reproduced by the TSFM calculations over the temperature range of 1.1-1.7 MeV.PACS numbers: 24.30Cz;21.60-n;27.70+q * nanal@tifr.res.in 1 arXiv:1704.04863v2 [nucl-ex]