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The characteristics of a low background germanium gamma ray spectrometer at China JinPing underground Laboratory

A low background germanium gamma ray spectrometer, GeTHU, has been installed at China JinPing underground Laboratory. The integral background count rate between 40 and 2700 keV was 0.6 cpm, and the origin was studied by Monte Carlo simulation. Detection limits and efficiencies were calculated for selected gamma peaks. Boric acid and silica sand samples were measured and 137Cs contamination was found in boric acid. GeTHU will be mainly used to measure environmental samples and screen materials in dark matter experiments.

physics.ins-det↗

FACT -- The G-APD revolution in Cherenkov astronomy

Since two years, the FACT telescope is operating on the Canary Island of La Palma. Apart from its purpose to serve as a monitoring facility for the brightest TeV blazars, it was built as a major step to establish solid state photon counters as detectors in Cherenkov astronomy. The camera of the First G-APD Cherenkov Telesope comprises 1440 Geiger-mode avalanche photo diodes (G-APD), equipped with solid light guides to increase the effective light collection area of each sensor. Since no sense-line is available, a special challenge is to keep the applied voltage stable although the current drawn by the G-APD depends on the flux of night-sky background photons significantly varying with ambient light conditions. Methods have been developed to keep the temperature and voltage dependent response of the G-APDs stable during operation. As a cross-check, dark count spectra with high statistics have been taken under different environmental conditions. In this presentation, the project, the developed methods and the experience from two years of operation of the first G-APD based camera in Cherenkov astronomy under changing environmental conditions will be presented.

astro-ph.IM↗

Asymmetries in Silicon Microstrip Response Function and Lorentz Angle

An experimental set up, dedicated to isolate an error present in the $η$-algorithm, gave an unexpected result. The average of a center of gravity algorithm at orthogonal particle incidence turns out to be non zero. This non zero average signals an asymmetry in the response function of the strips, and introduces a further parameter in the corrections: the shift of the strip response center of gravity respect its geometrical position. A strategy to extract this parameter from a standard data set is discussed. Some simulations with various asymmetric response functions are explored for this test. The method is able to detect easily the asymmetry parameters introduced in the simulations. Its robustness is tested against angular rotations, and we see an almost linear variation with the angle. This simple property is used to simulate a determination of a Lorentz angle with and without the asymmetry of the response function.

physics.ins-det↗

Prototype performance studies of a Full Mesh ATCA-based General Purpose Data Processing Board

High luminosity conditions at the LHC pose many unique challenges for potential silicon based track trigger systems. One of the major challenges is data formatting, where hits from thousands of silicon modules must first be shared and organized into overlapping eta-phi trigger towers. Communication between nodes requires high bandwidth, low latency, and flexible real time data sharing, for which a full mesh backplane is a natural solution. A custom Advanced Telecommunications Computing Architecture data processing board is designed with the goal of creating a scalable architecture abundant in flexible, non-blocking, high bandwidth board to board communication channels while keeping the design as simple as possible. We have performed the first prototype board testing and our first attempt at designing the prototype system has proven to be successful. Leveraging the experience we gained through designing, building and testing the prototype board system we are in the final stages of laying out the next generation board, which will be used in the ATLAS Level-2 Fast TracKer as Data Formatter, as well as in the CMS Level-1 tracking trigger R&D for early technical demonstrations.

physics.ins-det↗

Design, construction, commissioning and long term operational experience with the D0 Uranium/Liquid Argon calorimeter

The D0 experiment was designed in the mid 1980s and ran at the Fermilab pp collider from 1992 through 2011. I describe the uranium-liquid argon calorimeter and its readout electronic which was upgraded in the late 1990s to handle the higher luminosity of the upgraded Tevatron during its second running period from 2001-2011. I summarize maintaining the calorimeter for 20 years of data taking. I further describe a few issues that arose during that time, including different types of noise and the anomalous high voltage currents seen only in the central calorimeter.

physics.ins-det↗

Solar Neutrino Results from Super-Kamiokande

Super-Kamiokande-IV (SK-IV) data taking began in September of 2008, after upgrading the electronics and data acquisition system. Due to these upgrades and improvements to water system dynamics, calibration and analysis techniques, a solar neutrino signal could be extracted at recoil electron kinetic energies as low as 3.5 MeV. When the SK-IV data is combined with the previous three SK phases, the SK extracted solar neutrino flux is found to be $[2.37\pm0.015\mbox{(stat.)}\pm0.04\mbox{(syst.)}]\times10^6$/(cm$^{2}$sec). The combination of the SK recoil electron energy spectra slightly favors distortions due to a changing electron flavor content. Such distortions are predicted when assuming standard solar neutrino oscillation solutions. An extended maximum likelihood fit to the amplitude of the expected solar zenith angle variation of the neutrino-electron elastic scattering rate results in a day-night asymmetry of $[-3.2\pm1.1$(stat.)$\pm0.5$(syst.)]$\%$. A solar neutrino global oscillation analysis including all current solar neutrino data, as well as KamLAND reactor antineutrino data, measures the solar mixing angle as $\sin^2θ_{12}=0.305\pm0.013$, the solar neutrino mass squared splitting as $Δm^2_{21}=7.49^{+0.19}_{-0.17}\times10^{-5}$eV$^2$ and $\sin^2θ_{13}=0.026^{+0.017}_{-0.012}$.

hep-ex↗

Arbor, a new approach of the Particle Flow Algorithm

The granularity of calorimeter has been revolutionary boosted for future collider experiments. The calorimeter has been pushed to a stage that the sub structure of showers especially hadronic showers can be recorded to a high precision. New reconstruction algorithms are expected from these informations. Following the idea that shower follows the topology of the tree, we developed Arbor, a Particle Flow Algorithm framework. Tested on both simulated data and test beam data, it can successfully separate nearby showers. It has comparable jet energy resolution the best PFA algorithm for International Linear Collider. More importantly, Arbor successfully tags the sub shower structure such as the trajectory of charged particles generated in shower cascade, enabling new approaches for event reconstruction with high granularity calorimeter.

physics.ins-det↗

Update on the MiniCLEAN Dark Matter Experiment

The direct search for dark matter is entering a period of increased sensitivity to the hypothetical Weakly Interacting Massive Particle (WIMP). One such technology that is being examined is a scintillation only noble liquid experiment, MiniCLEAN. MiniCLEAN utilizes over 500 kg of liquid cryogen to detect nuclear recoils from WIMP dark matter and serves as a demonstration for a future detector of order 50 to 100 tonnes. The liquid cryogen is interchangeable between argon and neon to study the A$^{2}$ dependence of the potential signal and examine backgrounds. MiniCLEAN utilizes a unique modular design with spherical geometry to maximize the light yield using cold photomultiplier tubes in a single-phase detector. Pulse shape discrimination techniques are used to separate nuclear recoil signals from electron recoil backgrounds. MiniCLEAN will be spiked with additional $^{39}$Ar to demonstrate the effective reach of the pulse shape discrimination capability. Assembly of the experiment is underway at SNOLAB and an update on the project is given.

physics.ins-det↗

Semiconductor phonon and charge transport Monte Carlo simulation using Geant4

A phonon and charge transport simulation based on the Geant4 Monte Carlo toolkit is presented. The transport code is capable of propagating acoustic phonons, electrons and holes in cryogenic crystals. Anisotropic phonon propagation, oblique carrier propagation and phonon emission by accelerated carriers are all taken into account. The simulation successfully reproduces theoretical predictions and experimental observations such as phonon caustics, heat pulse propagation times and mean carrier drift velocities. Implementation of the transport code using the Geant4 toolkit ensures availability to the wider scientific community.

physics.ins-det↗

Study of Tracking and Flavor Tagging with FPCCD Vertex Detector

One of the major physics goals at the ILC is the precise measurement of the Higgs coupling constants to b-quarks and c-quarks. To achieve this measurement, we need a high-performance vertex detector leading to precise flavor tagging. For this purpose, we are developing the Fine Pixel CCD (FPCCD) vertex detector. In this paper, we will report on the development status of FPCCDTrackFinder, a new track finder improving tracking efficiency, especially in the low $p_t$ region, and an evaluation result of the flavor tagging performance with FPCCDTrackFinder in the FPCCD vertex detector.

physics.ins-det↗

Status of the Forward Tracker Detector of ILD

An overview of the present activities and long-term R&D plans of the Spanish network for future linear accelerators aiming to design and construct the Forward Tracker Detector (FTD) system of ILD, is shown

physics.ins-det↗

A Proposal for an ALPs-Chameleon Experiments Station

It is generally accepted that certain astronomical and cosmological observations can be explained by invoking the concepts of Dark Matter and Dark Energy (DM/DE). Applying straightforward extensions of the Standard Model to DM/DE, results in scalar fields and predictions of particles generation via photo-magnetic coupling . Under the right conditions, these particles should be observable in earth-bound laboratory settings. Although many attempts have been made to observe these particles, none have succeeded. Heretofore, most searches have focused on detecting multi-GeV Dark Matter WIMPS. Recently, however, searches have been conducted in the lighter dark matter, sub-eV, WISP mass range. By comparison, little has been done to search for dark energy particles. The ALPs-Chameleon Experiments Stations (ACES) program, described herein, proposes a compact station that would search for both dark sector particles. Finally, it is noted that both "species" of particles - dark energy and dark matter - could be generated at the same time in the same magnetic field with the possibility of interaction between DM and DE particles. Thus, by using standard matter tools to produce particles from both dark sectors, ACES potentially could provide tri-sector discoveries with huge results for very little investment.

physics.ins-det↗

Improving Dark Matter Axion Searches with Active Resonators

Axions are a well motivated candidate for dark matter. The most sensitive experiments searching for dark matter axions rely on the coupling of axions to the electromagnetic resonances of a microwave cavity immersed in a strong magnetic field. The sensitivity of the experiment is proportional to the Q of the resonance that is coupled to axions. To date, the resonators used in axion searches have all been passive, with Qs limited by power loss in the cavity walls. I propose the use of active feedback resonators to increase the Q of microwave cavity axion dark matter experiments by several orders of magnitude. This should allow experiments to significantly increase the rate at which they can test potential axion masses and couplings.

physics.ins-det↗

The Status of Double Chooz Experiment as a proceeding of PIC 2013 conference

Double Chooz is a long baseline neutrino oscillation experiment at Chooz, France. The purpose of this experiment is to measure the non-zero neutrino oscillation parameter theta13, a parameter for changing electron neutrinos into other neutrinos. This experiment uses reactors of the Chooz Nuclear Power Plant as a neutrino source. Double Chooz has published 2 result papers showing the measurement of the mixing angle, and 3rd publication is processing.

hep-ex↗

Activity report of ILD-TPC Asia group

The purpose of ILD-TPC Asia group is realization of high precision Time Projection Chamber (TPC) with Gas Electron Multiplier (GEM) as a central tracker in International Linear Collider (ILC). We have been studying the many R&D items to build the real detector as a member of LCTPC collaboration. This paper describes the our efforts for realization of the ILD-TPC, the result of test beam using large prototype TPC, local field distortion, positive ion effects and gate devices, and cooling electronics which are key items to build ILD-TPC.

physics.ins-det↗

Resistive MSGC with double layered electrodes

The first successful attempts to optimize the electric field in Resistive Microstrip Gas Chamber (RMSGC) using additional field shaping strips located inside the detector substrate are described.

physics.ins-det↗

A study of silicon sensor for ILD ECAL

The International Large Detector (ILD) is a proposed detector for the International Linear Collider (ILC). It has been designed to achieve an excellent jet energy resolution by using Particle Flow Algorithms (PFA), which rely on the ability to separate nearby particles within jets. PFA requires calorimeters with high granularity. The ILD Electromagnetic Calorimeter (ECAL) is a sampling calorimeter with thirty tungsten absorber layers. The total thickness of this ECAL is about 24 X$_0$, and it has between 10 and 100 million channels to make high granularity. Silicon sensors are a candidate technology for the sensitive layers of this ECAL. Present prototypes of these sensors have 256 5.5$\times$5.5 mm$^2$ pixels in an area of 9$\times$9 cm$^2$.We have measured various properties of these prototype sensors: the leakage current, capacitance, and full depletion voltage. We have also examined the response to an infrared laser to understand the sensor's response at its edge and between pixel readout pads, as well the effect of different guard ring designs. In this paper, we show results from these measurements and discuss future works.

physics.ins-det↗

Gain Stabilization of SiPMs

The gain of SiPMs depends both on bias voltage and on temperature. For stable operations, both need to be kept constant. In an ILC calorimeter with millions of channels, this is a challenging task. It is, therefore, desirable to compensate for temperature variations by automatically readjusting the bias voltage. We have designed a bias voltage regulator board to achieve this task. We anticipate an uncertainty on the gain stability at the level of $< 1\%$. First, we present measurements of the gain dependence on temperature and bias voltage for several SiPMs from three different manufacturers and determine their dV/dT dependence. Next, we demonstrate the performance of the gain stability with the bias voltage regulator test board on four SiPMs.

physics.ins-det↗