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The magnetised 51 kton Iron Calorimeter (ICAL) detector proposed to be built at INO is designed with a focus on detecting 1-20 GeV muons. The magnetic field will enable the measurement of the momentum of the $\mu^-$ and $\mu^+$ generated from the charge current interactions of $\nu_\mu$ and $\bar\nu_\mu$ separately within iron in the detector, thus permitting the determination of the neutrino mass ordering/hierarchy, among other important goals of ICAL. Hence it is important to determine the magnetic field as accurately as possible. The mini-ICAL detector is an 85-ton prototype of ICAL, which is operational at Madurai in South India. We describe here the first measurement of the magnetic field in mini-ICAL using Hall sensor PCBs. A set-up developed to calibrate the Hall probe sensors using an electromagnet. The readout system has been designed using an Arduino Nano board for selection of channels of Hall probes mounted on the PCB and to convert the analog voltage to a digital output. The magnetic field has been measured in the small gaps (provided for the purpose) between iron plates in the top layer of mini-ICAL as well as in the air just outside the detector. A precision of better than 3% was obtained, with a sensitivity down to about 0.03 kGauss when measuring the small fringe fields outside the detector., Comment: 13 pages, 17 figures, latex

The unstable nucleus $^8$Be, with its two $\alpha$-cluster configuration, is the doorway to the formation of heavier $\alpha$-cluster nuclei. Most importantly, its the precursor of the production of $^{12}$C through the Hoyle state, a resonance state of three $\alpha$ clusters, in the helium burning phase of a massive star. The nucleus exhibits a ground state band of rotational states established through $\alpha-\alpha$ scattering experiments. A subsequent precision particle-$\gamma$ coincidence measurement of the electromagnetic transition between the 4$^+\rightarrow$ 2$^+$ excited states also corroborated the evidence for a highly deformed dumb-bell shaped structure of $^8$Be. A simultaneous phenomenological R-matrix analysis of the measured capture reaction cross sections along with the elastic excitation function and phase shift data has been performed. The resulting reduced transition strength of 21.96$\pm$3.86 $e^2 fm^4$ compares well with the estimated experimental value of 21.0$\pm$2.3 e$^2$ fm$^4$. The R-matrix yield of the B($E2$) value is closer to the prediction of cluster model but about 19$\%$ less than the {\it ab initio} result.

INO-ICAL is a proposed underground particle physics experiment to study the neutrino oscillation parameters by detecting neutrinos produced in the atmospheric air showers. Iron CALorimeter (ICAL) is to have 151 layers of iron stacked vertically, with active detector elements in between the iron layers. The iron layers will be magnetized to enable the measurement of momentum and charge of the $\mu^-$ (or $\mu^+$) produced by $\nu_\mu$ (or $\bar{\nu}_\mu$) interactions. Resistive Plate Chambers (RPCs) have been chosen as the active detector elements due to their large area coverage, uncompromised sensitivity, consistent performance for decades, as well as cost effectiveness. The major factors that decide the physics potential of the ICAL experiment are efficiency, position resolution and time resolution of the large area RPCs. A prototype detector called miniICAL (with 11 iron layers) was commissioned to understand the engineering challenges in building the large scale magnet and its ancillary systems, and also to study the performance of the RPC detectors and readout electronics developed by the INO collaboration. As part of the performance study of the RPC detectors, an attempt is made to improve the position and time resolution of them. Even a small improvement in the position and time resolution will help to improve the measurements of momentum and directionality of the neutrinos in ICAL. The Time-over-Threshold (ToT) of the RPC pulses (signals) is recorded by the readout electronics. ToT is a measure of the pulse width and consequently the amplitude. This information is used to improve the time and position resolution of the RPCs and consequently INO physics potential.

An experimental setup consisting of 12 layers of glass Resistive Plate Chambers (RPCs) of size 2\,m\,$\times$\,2\,m has been built at IICHEP-Madurai (\ang{9;56;14.5}\,N \ang{78;00;47.9}\,E, on the surface) to study the long term performance and stability of RPCs produced on large scale in Indian industry. This setup has been collecting data triggered by the passage of charged particles. The measurement of the multiplicity of charged particles due to cosmic ray interactions are presented here. Finally, the results are compared with different hadronic models of the CORSIKA simulation.

The proposed 50 \,kton\, INO-ICAL experiment is an upcoming underground high energy physics experiment planned to be commissioned at Bodi hills near Theni, India ($9^{\circ}57'N$, $77^{\circ}16'E$) to study various properties of neutrino oscillations using atmospheric neutrinos produced by extensive air shower phenomenon. The resistive plate chamber has been chosen as the active detector element for the proposed INO-ICAL. An experimental setup consisting a stack of 12 layers of glass resistive plate chambers each with a size of $\sim$2\,m$\times$2\,m has been built at IICHEP, Madurai to study the performance and long-term stability of the resistive plate chambers(RPCs) commercially produced in large quantities by the Indian industries as well as its electronics for the front-end and subsequent signal processing. In this study, the azimuthal dependence of muon flux at various zenith angles at Madurai (9$^{\circ}$56'N, 78$^{\circ}$00'E and at an altitude of 160\,m above mean sea level) has been presented along with the comparison of Monte Carlo from CORSIKA and HONDA predictions., Comment: arXiv admin note: text overlap with arXiv:1706.00901

The India-based Neutrino Observatory Project (INO) is a proposed underground high energy physics experiment at Theni, India to study the neutrino oscillation parameters using atmospheric neutrinos. The 50 kton magnetised INO-ICAL detector will require approximately 30,000 of 2m$\times$2m Resistive Plate Chambers (RPC) as sensitive detectors and proposed to operate for about 20 years. For success of the experiment, each of the RPCs has to function without showing any significant aging during the period of operation. Hence, various tests including a proper leak test are performed during and after production. The methods of leak rate calculation using conventional manometer are valid only when both the volume of the test subject and ambient pressure are kept constant. But both these quantities for a RPC gas gap depend widely on the ambient pressure and temperature. A proper quantitative estimation of the leak rate cannot be acquired from such pressure measurements. By monitoring the absolute pressures, both outside and inside of an RPC, along with the temperature, its leakage rate can be estimated. During the test period, the supporting button spacers inside an RPC may get detached due to manufacturing defect. This effect also needs to be detected., Comment: 15 pages

The Iron Calorimeter (ICAL) detector at the India based Neutrino Observatory (INO) is planned to be set up in an underground cavern with a rock overburden of more than 1 km. This overburden reduces the cosmic muon flux by a factor of 10$^{6}$ with respect to that at sea level. In this paper, we examine the possibility of a 100 m shallow depth ICAL (SICAL) detector. The cosmic muons would have to be detected in a veto detector surrounding ICAL with an efficiency of 99.99 % in order to have the same level of muon background leaking undetected through the veto detector as at the 1 km depth underground site. However, an additional background arises from interactions of cosmic muons with the rock. Since the neutral particles produced in such interactions can pass through the veto detector without any interaction, they can possibly mimic neutrino events in ICAL. In this paper, the results of a GEANT4 based simulation study to estimate the background signals due to muon induced interactions with the rock for SICAL are presented.

The motivation for a cosmic muon veto (CMV) detector is to explore the possibility of locating the proposed large Iron Calorimeter (ICAL) detector at the India based Neutrino Observatory (INO) at a shallow depth. An initial effort in that direction, through the assembly and testing of a $\sim$ 1 m $\times$ 1 m $\times$ 0.3 m plastic scintillator based detector, is described. The plan for making a CMV detector for a smaller prototype mini-ICAL is also outlined.

The 50 \,kton\, INO-ICAL is a proposed underground high energy physics experiment at Theni, India ($9^{\circ}57'N$, $77^{\circ}16'E$) to study the neutrino oscillation parameters using atmospheric neutrinos. The Resistive Plate Chamber (RPC) has been chosen as the active detector element for the ICAL detector. An experimental setup consisting of 12 layers of glass RPCs of size 2\,m\,$\times$\,2\,m has been built at IICHEP, Madurai to study the long term stability and performance of RPCs which are produced on a large scale in Indian industry. In this paper, the studies on the performance of RPCs are presented along with the angular distribution of muons at Madurai ($9^{\circ}56'N,78^{\circ}00'E$ and Altitude $\approx$\,160\,m from sea level)., Comment: Total number of pages 12 and 4 figures

An array of eight CsI(Tl) detectors has been set up to measure the light charged particles in nuclear reactions using heavy ions from the Pelletron Linac Facility, Mumbai. The energy response of CsI(Tl) detector to $\alpha$-particles from 5 to 40 MeV is measured using radioactive sources and the $^{12}$C($^{12}$C, $\alpha$) reaction populating discrete states in $^{20}$Ne. The energy non-linearity and the count rate effect on the pulse shape discrimination property have also been measured and observed the deterioration of pulse shape discrimination with higher count rate., Comment: 8 pages, 7 figures

The response of the liquid scintillator (EJ-301 equivalent to NE-213) to the monoenergetic electrons produced in Compton scattered $\gamma$-ray tagging has been carried out for various radioactive $\gamma$-ray sources. The measured electron response is found to be linear up to $\sim$4~MeVee and the resolution of the liquid scintillator at 1~MeVee is observed to be $\sim$~11\%. The pulse shape discrimination and pulse height response of the liquid scintillator for neutrons has been measured using $^7$Li(p,n$_1$)$^7$Be*(0.429 MeV) reaction. Non linear response to mono-energetic neutrons for the liquid scintillator is observed at E$_n$=5.3, 9.0 and 12.7 MeV. The measured response of the liquid scintillator for electrons and neutrons have been compared with Geant4 simulation., Comment: 10 pages, 9 figures, submitted to NIM A

The study has been carried out on the prospects of probing the sterile neutrino mixing with the magnetized Iron CALorimeter (ICAL) at the India-based Neutrino Observatory (INO), using atmospheric neutrinos as a source. The so-called 3~$+$~1 scenario is considered for active-sterile neutrino mixing and lead to projected exclusion curves in the sterile neutrino mass and mixing angle plane. The analysis is performed using the neutrino event generator NUANCE, modified for ICAL, and folded with the detector resolutions obtained by the INO collaboration from a full GEANT4 based detector simulation. A comparison has been made between the results obtained from the analysis considering only the energy and zenith angle of the muon and combined with the hadron energy due to the neutrino induced event. A small improvement has been observed with the addition of the hadron information to the muon. In the analysis we consider neutrinos coming from all zenith angles and the Earth matter effects are also included. The inclusion of events from all zenith angles improves the sensitivity to sterile neutrino mixing by about 35$\%$ over the result obtained using only down-going events. The improvement mainly stems from the impact of Earth matter effects on active-sterile mixing. The expected precision of ICAL on the active-sterile mixing is explored and allowed confidence level (C.L.) contours presented. At the assumed true value of $10^\circ$ for the sterile mixing angles and marginalization over $\Delta m^2_{41}$ and the sterile mixing angles, the upper bound at 90\% C.L. (from 2 parameter plots) is around $20^\circ$ for $\theta_{14}$ and $\theta_{34}$, and about $12^\circ$ for $\theta_{24}$., Comment: 13 pages, 9 figures, version published in Eur. Phys. J. C

Pairing reentrance phenomenon in the warm rotating $^{104}$Pd nucleus is studied within the Bardeen-Cooper-Schrieffer (BCS)-based approach (the FTBCS1). The theory takes into account the effect of quasiparticle number fluctuations on the pairing field at finite temperature and angular momentum within the pairing model plus noncollective rotation along the symmetry axis. The numerical calculations for the pairing gaps and nuclear level densities (NLD), of which an anomalous enhancement has been experimentally observed at low excitation energy $E^*$ and high angular momentum $J$, show that the pairing reentrance is seen in the behavior of pairing gap obtained within the FTBCS1 at low $E$ and high $J$. This leads to the enhancement of the FTBCS1 level densities, in good agreement with the experimental observation. This agreement indicates that the observed enhancement of the NLD might be the first experimental detection of the pairing reentrance in a finite nucleus., Comment: 8 pages, 2 figures, invited lecture presented by N. Dinh Dang at the XVII Nuclear Physics Workshop "Marie & Pierre Curie", 22 - 27 September 2015, Kazimierz Dolny, Poland, submitted to Acta Physica Polonica

The 50~kton Iron Calorimeter (ICAL) detector at the underground India based Neutrino Observatory (INO) will make measurements on atmospheric neutrinos. Muons produced in charged current (CC) interactions of muon neutrinos with the iron are tracked spatially and temporally through the signals that they produce in the Resistive Plate Chambers~(RPCs) that are interleaved with iron layers. Since the RPCs will be operated in the avalanche mode the signal rise-time is $\sim~1~\rm{nsec}$ resulting in a fast time response. While the muon track is derived from the X and Y hit information of the RPCs and the layer number (Z), the upward or downward direction is obtained by using the time information from the detector. Such a capability can be examined by analysing the timing information from $1~\rm{m}~\times~1~\rm{m}$ glass RPCs, with $3~\rm{cm}$ wide X- and Y- pick-up strips, in a $12$ layer RPC stack that measures cosmic muon events. The present study looks at the pixel-wise time response of these RPCs in order to improve the relative time distribution and hence the up-down discrimination capability. After including the effect of propagation delay in the cable and pick-up panel the time resolution improves, in some cases, to $\leq~1~\rm{nsec}$ whereas in some cases there is no significant change. These results will help in significantly improving on the extraction of the directionality of muons produced in CC interactions of $\nu_{\mu}$ and $\bar{\nu}_{\mu}$., Comment: 10 pages, 6 figures

We report on the simulation studies on the possibility of dark matter particle (DMP) decaying into leptonic modes. While not much is known about the properties of dark matter particles except through their gravitational effect, it has been recently conjectured that the so called "anomalous Kolar Events" observed some decades ago may be due to the decay of unstable dark matter particles (M.V.N. Murthy and G.Rajasekaran, Pramana, {\bf 82}, 609 (2014)). The aim of this study is to see if this conjecture can be verified at the proposed Iron Calorimeter (ICAL) detector at INO. We study the possible decay to leptonic modes which may be seen in this detector with some modifications. For the purposes of simulation we assume that each channel saturates the decay width for the mass ranging from $1-50 \rm{GeV/c^2}$. The aim is not only to investigate the decay signatures, but also, more generally, to establish lower bounds on the life time of DMP even if no such decay takes place., Comment: 14 pages, 6 figures

The iron calorimeter (ICAL) detector at the India-based Neutrino Observatory (INO) will be used to measure neutrino mass hierarchy. The magnet in the ICAL detector will be used to distinguish the {\mu^-} and {\mu^+} events induced by {\nu_{\mu}} and {\bar{\nu_{\mu}}}, respectively. Due to the importance of the magnet in ICAL, an electromagnetic simulation has been carried out to study the B-field distribution in iron using various designs. The simulation shows better uniformity in the portion of the iron layer between the coils, which is bounded by regions which have lesser field strength as we move to the periphery of the iron layer. The ICAL magnet was configured to have a tiling structure that gave the minimum reluctance path while keeping a reasonably uniform field pattern.This translates into less Ampere-turns needed for generation of the required magnetic field. At low Ampere-turns, a larger fractional area with \vert B \vert \ge 1 Tesla (T) can be obtained by using a soft magnetic material. A study of the effect of the magnetic field on muon trajectories has been carried out using GEANT4. For muons up to 20 GeV, the energy resolution improves as the magnetic field increases from 1.1T to 1.8T. The charge identification efficiency for muons was found to be more than 90\% except for large zenith angles., Comment: 9 pages, 14 figures

Sub-relativistic magnetic monopoles are predicted from the GUT era by theory. To date there have been no confirmed observations of such exotic particles. The Iron CALorimeter (ICAL) at India-based Neutrino Observatory (INO) aims to measure the neutrino oscillation parameters precisely. As it is a tracking detector there is also the possibility of detecting magnetic monopoles in the sub-relativistic region. Using ICAL the magnetic monopole event is characterised by the large time intervals of upto 30 microsec between the signals in successive layers of the active detectors. The aim of this study is to identify the sensitivity of ICAL for a particle carrying magnetic charge in the mass range from 10^{5} to 10^{17} GeV with beta ranging from 10^{-5} to 9 x 10^{-1} for ICAL at INO. A similar study has also been carried out for the ICAL prototype which will be placed overground. Due to the rock cover of approximately 1.3 km, ICAL at INO will not be able to place bounds on the flux of the lower mass magnetic monopoles. This mass region is however addressed by the prototype ICAL., Comment: 13 pages, 8 figures

An earlier measurement on the 4$^+$ to 2$^+$ radiative transition in $^8$Be provided the first electromagnetic signature of its dumbbell-like shape. However, the large uncertainty in the measured cross section does not allow a stringent test of nuclear structure models. The present paper reports a more elaborate and precise measurement for this transition, via the radiative capture in the $^4$He+$^4$He reaction, improving the accuracy by about a factor of three. The {\it ab initio} calculations of the radiative transition strength with improved three-nucleon forces are also presented. The experimental results are compared with the predictions of the alpha cluster model and {\it ab initio} calculations., Comment: 5 pages and 7 figures, Submitted to Physical Review Letters

The damping of the nuclear shell effect with excitation energy has been measured through an analysis of the neutron spectra following the triton transfer in the $^7$Li induced reaction on $^{205}$Tl. The measured neutron spectra demonstrate the expected large shell correction energy for the nuclei in the vicinity of doubly magic $^{208}$Pb and a small value for $^{184}$W. A quantitative extraction of the allowed values of the damping parameter $\gamma$, along with those for the asymptotic nuclear level density parameter $\tilde{a}$, has been made for the first time., Comment: 5 pages, 5 figures

A large area plastic scintillator detector array(~ 1 m x1m) has been set up for fast neutron spectroscopy at the BARC-TIFR Pelletron laboratory, Mumbai. The energy, time and position response has been measured for electrons using radioactive sources and for mono-energetic neutrons using the 7Li(p,n1)7Be*(0.429 MeV) reaction at proton energies between 6.3 and 19 MeV. A Monte Carlo simulation of the energy dependent efficiency of the array for neutron detection is in agreement with the 7Li(p,n1) measurements. The array has been used to measure the neutron spectrum, in the energy range of 4-12 MeV, in the reaction 12C+ 93Nb at E(12C)= 40 MeV. This is in reasonable agreement with a statistical model calculation., Comment: 31 pages, 17 figures, submitted to NIM A

The low lying states in $^8$Be are believed to have a two-alpha cluster structure and hence a large intrinsic quadrupole deformation. An earlier calculation showed a large collective enhancement in gamma transition probability between the low lying states leading to a 4$^+$ to 2$^+$ gamma branch of $\sim10^{-7}$ and a resonant radiative cross section of 134 nb for the $\alpha+\alpha$ entrance channel. We report here the first experimental evidence for this transition through a $\gamma-\alpha-\alpha$ coincidence measurement in the reaction $^4$He($\alpha,\alpha \gamma$)$^4$He using a gas target. The measured cross sections on and off the 4$^+$ resonance are 165 $\pm$ 41 (stat) $\pm$35 (sys) nb and 39 $\pm$ 25 (stat) $\pm$7 (sys) nb, respectively., Comment: Total 4 pages, 4 figures, in RevTeX format, submitted to PRL

Angular distribution measurements of $^2$H($^7$Be,$^7$Be)$^2$H and $^2$H($^7$Be,$^8$B)$n$ reactions at $E_{c.m.}\sim$~4.5 MeV were performed to extract the astrophysical $S_{17}(0)$ factor using the asymptotic normalization coefficient (ANC) method. For this purpose a pure, low emittance $^7$Be beam was separated from the primary $^7$Li beam by a recoil mass spectrometer operated in a novel mode. A beam stopper at 0$^{\circ}$ allowed the use of a higher $^7$Be beam intensity. Measurement of the elastic scattering in the entrance channel using kinematic coincidence, facilitated the determination of the optical model parameters needed for the analysis of the transfer data. The present measurement significantly reduces errors in the extracted $^7$Be(p,$\gamma$) cross section using the ANC method. We get $S_{17}$~(0)~=~20.7~$\pm$~2.4 eV~b., Comment: 15 pages including 3 eps figures, one figure removed and discussions updated. Version to appear in Physical Review C