AbstractTransverse momentum spectra of charged hadrons with pT < 6 GeV/c have been measured near mid-rapidity (0.2 < η < 1.4) by the PHOBOS experiment at RHIC in Au + Au and d + Au collisions at ...\({\sqrt{s_{_{NN}}}~= \rm {200~GeV}}\). The spectra for different collision centralities are compared to \({p + \bar{p}}\) collisions at the same energy. The resulting nuclear modification factor for central Au + Au collisions shows evidence of strong suppression of charged hadrons in the high-pT region (>2 GeV/c). In contrast, the d + Au nuclear modification factor exhibits no suppression of the high-pT yields. These measurements suggest a large energy loss of the high-pT particles in the highly interacting medium created in the central Au + Au collisions. The lack of suppression in d + Au collisions suggests that it is unlikely that initial state effects can explain the suppression in the central Au + Au collisions. PACS: 25.75.-q
FPGA-based trigger system for the LUX dark matter experiment Akerib, D. S.; Araújo, H. M.; Bai, X. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2016, Volume:
818, Issue:
C
Journal Article
The LUX prototype detector: Heat exchanger development Akerib, D.S.; Bai, X.; Bedikian, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2013, Volume:
709, Issue:
C
Journal Article
Peer reviewed
Open access
The LUX (large underground xenon) detector is a two-phase xenon time projection chamber (TPC) designed to search for WIMP–nucleon dark matter interactions. As with all noble element detectors, ...continuous purification of the detector medium is essential to produce a large (>1ms) electron lifetime; this is necessary for efficient measurement of the electron signal which in turn is essential for achieving robust discrimination of signal from background events. In this paper, we describe the development of a novel purification system deployed in a prototype detector. The results from the operation of this prototype indicated heat exchange with an efficiency above 94% up to a flow rate of 42 slpm, allowing for an electron drift length greater than 1m to be achieved in approximately 2 days and sustained for the duration of the testing period.
First performance results of the Phobos silicon detectors Pernegger, H; Back, B.B; Baker, M.D ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2001, Volume:
473, Issue:
1
Journal Article
Peer reviewed
The Phobos experiment concluded its first year of operation at RHIC taking data in Au–Au nucleus collisions at
s
nn
=65
GeV
and
130
GeV/
nucleon pair. First preliminary results of the performances of ...our silicon detectors in the experiment are summarized. The Phobos experiment uses silicon pad detectors for both tracking and multiplicity measurements. The silicon sensors vary strongly in their pad geometry. In this paper, we compare the signal response, the signal uniformity and signal-to-noise performance as measured in the experiment for the different geometries. Additionally, we investigate effects of very high channel occupancy on the signal response.
Recent results from PHOBOS at RHIC Back, B.B.; Baker, M.D.; Ballintijn, M. ...
Brazilian journal of physics,
09/2004, Volume:
34, Issue:
3a
Journal Article
Peer reviewed
Open access
PHOBOS is one of the four heavy ion experiments currently running at the Relativistic Heavy Ion Collider (RHIC). In this paper we will present some of the current results from PHOBOS: the study of ...charged multiplicity distribution as function of pseudorapidity and centrality at or = 19.6, 130 and 200 GeV, a discussion of multiplicity scaling, and a measurement of transverse momentum spectra (pT) of charged hadrons produced in d+Au and Au+Au interactions at or = 200 GeV. The dependence of the Au+Au yields as function of centrality is found to be independent of pT. A strong suppression in the Au+Au hadron spectra relative to p at high pT is observed. The spectral shape for d+Au collisions is significantly different from the observations in Au+Au, the yield suppression is not observed in d+Au.
An ultra-low background PMT for liquid xenon detectors Akerib, D. S.; Bai, X.; Bernard, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2012, Volume:
703, Issue:
C
Journal Article
Peer reviewed
Open access
Results are presented from radioactivity screening of two models of photomultiplier tubes designed for use in current and future liquid xenon experiments. The Hamamatsu 5.6 cm diameter R8778 PMT, ...used in the LUX dark matter experiment, has yielded a positive detection of four common radioactive isotopes: 238U, 232Th, 40K, and 60Co. Screening of LUX materials has rendered backgrounds from other detector materials subdominant to the R8778 contribution. A prototype Hamamatsu 7.6 cm diameter R11410 MOD PMT has also been screened, with benchmark isotope counts measured at <0.4 238U / <0.3 232Th / < 8.340K / 2.0+-0.2 60Co mBq/PMT. This represents a large reduction, equal to a change of x $\frac{1}{24}$ 238U / x $\frac{1}{9}$ 232Th / x $\frac{1}{8}$ 40K per PMT, between R8778 and R11410 MOD, concurrent with a doubling of the photocathode surface area (4.5 cm to 6.4 cm diameter). 60Co measurements are comparable between the PMTs, but can be significantly reduced in future R11410 MOD units through further material selection. Assuming PMT activity equal to the measured 90% upper limits, Monte Carlo estimates indicate that replacement of R8778 PMTs with R11410 MOD PMTs will change LUX PMT electron recoil background contributions by a factor of x $\frac{1}{25}$ after further material selection for 60Co reduction, and nuclear recoil backgrounds by a factor of \times $\frac{1}{36}$. The strong reduction in backgrounds below the measured R8778 levels makes the R11410 MOD a very competitive technology for use in large-scale liquid xenon detectors.
Multifragmentation for
129Xe-induced reactions on several targets (
natCu,
89Y,
165Ho,
197Au) has been studied at
E
A
= 40, 50
and 60 MeV
. The probability of emitting
n intermediate mass fragments ...is shown to be binomial at each transversal energy and reducible to an elementary binary probability
p. For each target and at each bombarding energy,
p shows a thermal behavior as demonstrated by linear Arrhenius plots. A nearly universal linear Arrhenius plot is observed at each bombarding energy, independent of target. The sensitivity of
p to the Z
threshold points to its physical significance and rules out auto-correlation effects.
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