Strangeness in nuclear physics Gal, A.; Hungerford, E. V.; Millener, D. J.
Reviews of modern physics,
08/2016, Volume:
88, Issue:
3
Journal Article
Peer reviewed
Open access
Extensions of nuclear physics to the strange sector are reviewed, covering data and models of Lambda and other hypernuclei, multistrange matter, and antikaon bound states and condensation. Past ...achievements are highlighted, present unresolved problems are discussed, and future directions are outlined.
The DarkSide-50 direct-detection dark matter experiment is a dual-phase argon time projection chamber operating at Laboratori Nazionali del Gran Sasso. This paper reports on the blind analysis of a ...(16 660±270) kg d exposure using a target of low-radioactivity argon extracted from underground sources. We find no events in the dark matter selection box and set a 90% C.L. upper limit on the dark matter–nucleon spin-independent cross section of 1.14×10−44 cm2 (3.78×10−44 cm2, 3.43×10−43 cm2) for a WIMP mass of 100 GeV/c2 (1 TeV/c2, 10 TeV/c2).
This paper derives equations for the deflection of an anode wire in a proportional straw chamber under electrostatic forces due to misalignments of the wire, deformation of the straw tube surface, ...and gravity.
The EuroRotaNet surveillance network has conducted rotavirus genotype surveillance since 2007 in 16 European countries. Using epidemiological and microbiological data from 39,786 genotyped ...rotavirus-positive specimens collected between September 2007 and August 2013, we assessed genotype distribution and age distribution of rotavirus gastroenteritis (RVGE) cases in and out of peak season in 12 countries which were yet to implement routine rotavirus vaccination. In multinomial multivariate logistic regression, adjusting for year, country and age, the odds of infection caused by genotype-constellation 2 DS-1-like stains (adjusted multinomial odds ratio (aM-OR) = 1.25; 95% confidence interval (CI): 1.13-1.37; p < 0.001), mixed or untypable genotypes (aM-OR = 1.55; 95% CI: 1.40-1.72; p < 0.001) and less common genotypes (aM-OR = 2.11; 95% CI:1.78-2.51; p < 0.001) increased out of season relative to G1P8. Age varied significantly between seasons; the proportion of RVGE cases younger than 12 months in the United Kingdom increased from 34% in season to 39% out of season (aM-OR = 1.66; 95% CI: 1.20-2.30), and the proportion five years and older increased from 9% in season to 17% out of season (aM-OR = 2.53; 95% CI: 1.67-3.82). This study provides further understanding of the rotavirus ecology before vaccine introduction, which will help interpret epidemiological changes in countries introducing or expanding rotavirus vaccination programmes.
We reanalyze data collected with the DarkSide-50 experiment and recently used to set limits on the spin-independent interaction rate of weakly interacting massive particles (WIMPs) on argon nuclei ...with an effective field theory framework. The dataset corresponds to a total (16660 ± 270) kg d exposure using a target of low-radioactivity argon extracted from underground sources. We obtain upper limits on the effective couplings of the 12 leading operators in the nonrelativistic systematic expansion. For each effective coupling we set constraints on WIMP-nucleon cross sections, setting upper limits between 2.4 × 10−45 cm2 and 2.3 × 10−42 cm2 ( 8.9 × 10−45 cm2 and 6.0 × 10−42 cm2 ) for WIMPs of mass of 100 GeV/c2 ( 1000 GeV/c2) at 90% confidence level.
The data acquisition architecture for the tracking detector of the MECO experiment will consist of a preamplifier/discriminator feeding a buffered digitizer which will be controlled by programmable ...logic. The digitizer converts the timing and analog waveform into digital storage for later readout. In order to evaluate this conceptual design, a prototype system was assembled using an existing digitizer chip, which had similar characteristics to the one proposed for MECO. In this prototype system, the event readout sequence and trigger was controlled by a Xilinx FPGA, and gated data events were transferred for further processing to higher levels in the data stream. The system contained 64 input channels divided into four groups of 16 channels, and either anode or cathode signals could be processed. It could be operated in either an internal or external trigger mode. Test results are reported in this paper, including the maximum event rate, the system dead time, and the relationship between the system efficiency and the hitmap selection. Based on these test results, some improvements in the digitizer chip are discussed, and the specifications of our proposed digitizer are presented.
A front-end digitizing system is needed for the straw tracking-detector of the MECO experiment. This detector has 24 000 channels of time and amplitude readout. The system operates in a high singles ...count-rate environment, and continuously digitizes the incoming pulses of every channel, using a latency buffer to temporarily hold this information. For each event, channel occupancy signals are sent to a local logic analyzer. Thus, the system can be self-triggered or triggered by a coincidence of the internally generated occupancy signal with an external gate. Upon presentation of a valid trigger, all data stored in the latency buffer are then read with zero-suppression to local RAM. The readout can provide sub-nanosecond timing and 6-9-bit amplitude resolution. This digitizer design will be implemented in an ASIC due to the large number of readout channels, the requirement that the data initially flow in parallel because of high single rates, and the large number of memory buffers. The digitizer is controlled by an FPGA, and the system clock can be varied between 15-60 MHz. This paper presents the conceptual design for the MECO readout system, but we anticipate that it can be used for many other applications requiring the acquisition of time and waveform signals in high counting rate environments.
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