Pulse Shape Discrimination of CsI(Tl) with a Photomultiplier Tube and MPPCs

In this study, we evaluate and compare the pulse shape discrimination (PSD) performance of multipixel photon counters (MPPCs, also known as silicon photomultiphers - SiPMs) with that of a typical photomultiplier tube (PMT) when testing using CsI(Tl) scintillators. We use the charge comparison method, whereby we discriminate different types of particles by the ratio of charges integrated within two time-gates (the delayed part and the entire digitized waveform). For a satisfactory PSD performance, a setup should generate many photoelectrons (p.e.) and collect their charges efficiently. The PMT setup generates more p.e. than the MPPC setup does. With the same digitizer and the same long time-gate (the entire digitized waveform), the PMT setup is also better in charge collection. Therefore, the PMT setup demonstrates better PSD performance. We subsequently test the MPPC setup using a new data acquisition (DAQ) system. Using this new DAQ, the long time-gate is extended by nearly four times the length when using the previous digitizer. With this longer time-gate, we collect more p.e. at the tail part of the pulse and almost all the charges of the total collected p.e. Thus, the PSD performance of the MPPC setup is improved significantly. This study also provides an estimation of the short time-gate (the delayed part of the digitized waveform) that can give a satisfactory PSD performance without an extensive analysis to optimize this gate

EXTENSIBLE DATABASE FRAMEWORK FOR MANAGEMENT OF UNSTRUCTURED AND SEMI-STRUCTURED DOCUMENTS

Method and system for querying a collection of Unstructured or semi-structured documents to identify presence of, and provide context and/or content for, keywords and/or keyphrases. The documents are analyzed and assigned a node structure, including an ordered sequence of mutually exclusive node segments or strings. Each node has an associated set of at least four, five or six attributes with node information and can represent a format marker or text, with the last node in any node segment usually being a text node. A keyword (or keyphrase) is specified. and the last node in each node segment is searched for a match with the keyword. When a match is found at a query node, or at a node determined with reference to a query node, the system displays the context andor the content of the query node

Prototyping of DSSDs for Particle Tracking and Spectroscopy within the EXL Project at Fair

Prototype double-sided silicon strip detectors (DSSD$s$) of 300 $\mu$m thickness produced at PTI St. Petersburg (Russia) were tested for the use as position sensitive, $\Delta E$ and E detectors for tracking and particle identification in the EXL (EXotic nuclei studied in Light-ion induced reactions at the NESR storage ring) setup at the FAIR (Facility for Antiproton and Ion Research) project at GSI. We describe the characteristics of detectors with $16 \times 16,\;64\times 64$ and $64\times 16$ strips, respectively. The response of these detectors for $^{241}$Am $\alpha$ particles injected either from the p or n side was examined. The test measurements were performed partially at GSI and the University of Edinburgh. A first in-beam test with a proton beam of 50 MeV with the latter two DSSDs and two 6.5 mm thick Si(Li) detectors was also done at KVI Groningen, the Netherlands. The results reveal good spectroscopic properties of these detectors

An integrative framework of preemption strategies

Pre-print; author's draftThis paper performs a review of the various pre-emption strategies prescribed in the economics literature. These are cost superiority, consumers' switching cost, channel exclusivity, environmental barriers of entry and credible commitment to react aggressively. Through our analysis, we develop an integrative framework of the pre-emption strategies that will result in long-term payoffs to the firm. The framework proposes that there are two key dimensions—strategic advantage and strategic focus—and identify five generic types of pre-emption strategies for market incumbents. These are the switching cost, blockade, credible commitment, tie-up, and cost leadership strategies. The pre-emption strategies and the framework presented can assist managerial decision-making for the successful pre-emption of potential competition to complement their existing efforts

Status of 48Ca double beta decay search and its future prospect in CANDLES

CANDLES(CAlcium fluoride for the study of Neutrinos and Dark matters by Low Energy Spectrometer) is the experiment to search for the neutrino-less double beta decay(0vββ) of 48Ca with CaF2 scintillator. 48Ca has the highest Qββ-value (4.3 MeV) among all isotope candidates for 0vββ. It enables us to measure signals with very low background condition. After rejection analysis with 131 days × 86 kg data for background events from radioactive contaminations in the CaF2 scintillators, no events are observed in the Qββ-value region. As a result, the 0vββ half-life of 48Ca is greater than 6.2 × 1022 yr (90% confidence level). For further high sensitive measurement of 48Ca 0vββ search, we have been developing the 48Ca enrichment and CaF2 scintillating bolometer techniques. In this paper, the latest result for CANDLES and the status of scintillating bolometer development are described

Status and future prospect of 48Ca double beta decay search in CANDLES

The observation of neutrino-less double beta decay (0νββ) would be the most practical way to prove the Majorana nature of the neutrino and lepton number violation. CANDLES studies 48Ca double beta decay using CaF2 scintillator. The main advantage of 48Ca is that it has the highest Q-value (4.27 MeV) among all the isotope candidates for 0νββ. The CANDLES III detector is currently operating with 300kg CaF2 crystals in the Kamioka underground observatory, Japan. In 2014, a detector cooling system and a magnetic cancellation coil was installed with the aim to increase light emission of CaF2 scintillator and photo-electron collection efficiency of the photo-multipliers. After this upgrade, light yield was increased to 1000 p.e./MeV which is 1.6 times larger than before. According to data analysis and simulation, main background source in CANDLES is turned out to be high energy external gamma-ray originating neutron capture on the surrounding materials, so called (n,γ). Upgrading the detector by installing neutron and gamma-ray shield can reduce the remaining main backgrounds by two order magnitude. In this report, we discuss the detail of (n,γ) and background reduction by additional shielding