SOUVENIR ALL INDIA COORDINATED RESEARCH PROJECT FOR DRYLAND AGRICULTURE CRIDA, HYDERABAD XV Working Group Meeting (24th-27th December, 2015) BISWANATH CHARIALI CENTRE ASSAM AGRICULTURAL UNIVERSITY

Not AvailableIt is my proud privilege to express heartfelt thanks to the entire AICRPDA family for giving me the responsibility of bringing out a souvenir to commemorate the occasion of XVth Working Group Meeting of AICRPDA at Biswanath Chariali Centre, BNCA, Assam Agricultural University. I, on behalf of the editorial board do extend a warm welcome to all delegate scientists and dignitaries coming from different parts of our country to this holy historic place of Biswanath, popularly known as ‘Gupta Kanshi’. Holding such a mega event of national importance for the first time at a place like Biswanath Chariali at the far east of the country amidst the bounty of natural resources and an area being almost entirely rainfed is of great significance. In view of the aim of realizing the dream of another green revolution that is envisaged from the rainfed areas of the country particularly the eastern and north eastern parts; this workshop is expected to march ahead further for achieving the goal. The vast ‘Gene’ resource of the North East India offers plenty of scope for their utilization to cope up the challenges of rainfed agriculture. This is a challenging task of converting these ‘Gene’ resources into viable ‘Seed Resources’ for their commercial exploitation keeping the very natural resource base and integrity unaltered. A holistic effort with all modern technological interventions is the need of the hour to bring into sustainable utilization of the natural resource base of the region. The idea of bringing out the souvenir in its present form came with the realization of the need of accumulating the multitude of the concepts required for framing the objectives of rainfed area research particularly for the North Eastern part of India. I am fortunate to have the wholehearted response from many luminaries from several ICAR institutes including CRIDA and number dignified scientists from the Assam Agricultural University contributing their valuable articles. I, do express gratitude and thankfulness from my inner core of the heart to all of them for their valuable contributions. I am extremely grateful to the Honorable Vice Chancellor, AAU, Dr. Kamalmalla Bujarbaruah sir, for his constant inspiration and suggestions all along the organization of the workshop. I would also like to express my sincere gratitude to Dr. Srinivasa Rao, Director, CRIDA, Dr. G. N. Hazarika, Director of Research (Agri), AAU, Dr.G.Rabindra Charry, PC, AICRPDA, Dr. T.C. Baruah, Associate Dean, BNCA, Dr. P.K. Sarma, CS, AICRPDA and all associated scientists for their encouragement, moral support and valuable suggestions. Last but not the least, all the Research Associates working under AICRPDA, BNCA, do deserve due share of thanks for their all round helps in bringing out the souvenir.Not Availabl

Search for low-mass dark matter with CDMSlite using a profile likelihood fit

The Cryogenic Dark Matter Search low ionization threshold experiment (CDMSlite) searches for interactions between dark matter particles and germanium nuclei in cryogenic detectors. The experiment has achieved a low energy threshold with improved sensitivity to low-mass (/c2) dark matter particles. We present an analysis of the final CDMSlite data set, taken with a different detector than was used for the two previous CDMSlite data sets. This analysis includes a data salting method to protect against bias, improved noise discrimination, background modeling, and the use of profile likelihood methods to search for a dark matter signal in the presence of backgrounds. We achieve an energy threshold of 70 eV and significantly improve the sensitivity for dark matter particles with masses between 2.5 and 10 GeV/c2 compared to previous analyses. We set an upper limit on the dark matter-nucleon scattering cross section in germanium of 5.4×10−42 cm2 at 5 GeV/c2, a factor of ∼2.5 improvement over the previous CDMSlite result

Constraints on low-mass, relic dark matter candidates from a surface-operated SuperCDMS single-charge sensitive detector

This article presents an analysis and the resulting limits on light dark matter inelastically scattering off of electrons, and on dark photon and axionlike particle absorption, using a second-generation SuperCDMS high-voltage eV-resolution detector. The 0.93 g Si detector achieved a 3 eV phonon energy resolution; for a detector bias of 100 V, this corresponds to a charge resolution of 3% of a single electron-hole pair. The energy spectrum is reported from a blind analysis with 1.2 g-days of exposure acquired in an above-ground laboratory. With charge carrier trapping and impact ionization effects incorporated into the dark matter signal models, the dark matter-electron cross section σ_e is constrained for dark matter masses from 0.5 to 10⁴  MeV/c²; in the mass range from 1.2 to 50  eV/c² the dark photon kinetic mixing parameter ϵ and the axioelectric coupling constant gae are constrained. The minimum 90% confidence-level upper limits within the above-mentioned mass ranges are σ_e = 8.7×10⁻³⁴ cm², ϵ = 3.3×10⁻¹⁴, and g_(ae) = 1.0×10⁻⁹

Light Dark Matter Search with a High-Resolution Athermal Phonon Detector Operated Above Ground

We present limits on spin-independent dark matter-nucleon interactions using a $10.6$ $\mathrm{g}$ Si athermal phonon detector with a baseline energy resolution of $\sigma_E=3.86 \pm 0.04$ $(\mathrm{stat.})^{+0.19}_{-0.00}$ $(\mathrm{syst.})$ $\mathrm{eV}$. This exclusion analysis sets the most stringent dark matter-nucleon scattering cross-section limits achieved by a cryogenic detector for dark matter particle masses from $93$ to $140$ $\mathrm{MeV}/c^2$, with a raw exposure of $9.9$ $\mathrm{g}\cdot\mathrm{d}$ acquired at an above-ground facility. This work illustrates the scientific potential of detectors with athermal phonon sensors with eV-scale energy resolution for future dark matter searches.Comment: 7 pages, 4 figures, this version includes ancillary files from official data releas

Ionization yield measurement in a germanium CDMSlite detector using photo-neutron sources

Two photo-neutron sources, $^{88}$Y$^{9}$Be and $^{124}$Sb$^{9}$Be, have been used to investigate the ionization yield of nuclear recoils in the CDMSlite germanium detectors by the SuperCDMS collaboration. This work evaluates the yield for nuclear recoil energies between 1 keV and 7 keV at a temperature of $\sim$ 50 mK. We use a Geant4 simulation to model the neutron spectrum assuming a charge yield model that is a generalization of the standard Lindhard model and consists of two energy dependent parameters. We perform a likelihood analysis using the simulated neutron spectrum, modeled background, and experimental data to obtain the best fit values of the yield model. The ionization yield between recoil energies of 1 keV and 7 keV is shown to be significantly lower than predicted by the standard Lindhard model for germanium. There is a general lack of agreement among different experiments using a variety of techniques studying the low-energy range of the nuclear recoil yield, which is most critical for interpretation of direct dark matter searches. This suggests complexity in the physical process that many direct detection experiments use to model their primary signal detection mechanism and highlights the need for further studies to clarify underlying systematic effects that have not been well understood up to this point

Search for low-mass dark matter via bremsstrahlung radiation and the Migdal effect in SuperCDMS

We present a new analysis of previously published SuperCDMS data using a profile likelihood framework to search for sub-GeV dark matter (DM) particles through two inelastic scattering channels: bremsstrahlung radiation and the Migdal effect. By considering these possible inelastic scattering channels, experimental sensitivity can be extended to DM masses that are undetectable through the DM-nucleon elastic scattering channel, given the energy threshold of current experiments. We exclude DM masses down to 220  MeV/c2 at 2.7×10−30  cm2 via the bremsstrahlung channel. The Migdal channel search provides overall considerably more stringent limits and excludes DM masses down to 30  MeV/c2 at 5.0×10−30  cm2