LUX-ZEPLIN (LZ) is a second-generation direct dark matter experiment with spin-independent WIMP-nucleon scattering sensitivity above
1.4
×
10
-
48
cm
2
for a WIMP mass of
40
GeV
/
c
2
and a
1000
days
...exposure. LZ achieves this sensitivity through a combination of a large
5.6
t
fiducial volume, active inner and outer veto systems, and radio-pure construction using materials with inherently low radioactivity content. The LZ collaboration performed an extensive radioassay campaign over a period of six years to inform material selection for construction and provide an input to the experimental background model against which any possible signal excess may be evaluated. The campaign and its results are described in this paper. We present assays of dust and radon daughters depositing on the surface of components as well as cleanliness controls necessary to maintain background expectations through detector construction and assembly. Finally, examples from the campaign to highlight fixed contaminant radioassays for the LZ photomultiplier tubes, quality control and quality assurance procedures through fabrication, radon emanation measurements of major sub-systems, and bespoke detector systems to assay scintillator are presented.
LUX-ZEPLIN (LZ) is a second-generation direct dark matter experiment with spin-independent WIMP-nucleon scattering sensitivity above 1.4 × 10-48 cm2 for a WIMP mass of 40 GeV/c 2 and a 1000 d ...exposure. LZ achieves this sensitivity through a combination of a large 5.6 t fiducial volume, active inner and outer veto systems, and radio-pure construction using materials with inherently low radioactivity content. The LZ collaboration performed an extensive radioassay campaign over a period of six years to inform material selection for construction and provide an input to the experimental background model against which any possible signal excess may be evaluated. The campaign and its results are described in this paper. We present assays of dust and radon daughters depositing on the surface of components as well as cleanliness controls necessary to maintain background expectations through detector construction and assembly. Finally, examples from the campaign to highlight fixed contaminant radioassays for the LZ photomultiplier tubes, quality control and quality assurance procedures through fabrication, radon emanation measurements of major sub-systems, and be spoke detector systems to assay scintillator are presented.
The QUEST Large Area CCD Camera Baltay, C.; Rabinowitz, D.; Andrews, P. ...
Publications of the Astronomical Society of the Pacific,
11/2007, Volume:
119, Issue:
861
Journal Article
Peer reviewed
Open access
We have designed, constructed, and put into operation a very large area CCD camera that covers the field of view of the 1.2 m Samuel Oschin Schmidt Telescope at the Palomar Observatory. The camera ...consists of 112 CCDs arranged in a mosaic of four rows with 28 CCDs each. The CCDs are
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pixel Sarnoff thinned, back‐illuminated devices with
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pixels. The camera covers an area of
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on the sky with an active area of 9.6 deg2. This camera has been installed at the prime focus of the telescope and commissioned, and scientific‐quality observations on the Palomar‐QUEST Variability Sky Survey were started in 2003 September. The design considerations, construction features, and performance parameters of this camera are described in this paper.
Background
Procarbazine usage in brain tumors has a high incidence of hypersensitivity reactions compared with its use in other malignancies. Procarbazine oxidation to a reactive intermediate is ...enhanced by phenobarbital. Patients with primary brain tumors would have a preferential exposure to anticonvulsants compared to patients with other malignancies.
Objective
To determine whether anticonvulsant exposure is associated with procarbazine hypersensitivity reactions in patients with primary brain tumors.
Methods
This retrospective cohort study included 83 patients with primary brain tumors who were treated with procarbazine between 1981 and 1996 at a university hospital‐based regional oncology center. Data were extracted by chart review. The data collected included age, sex, race, tumor type, smoking, alcohol usage, and all concomitant medications, as well as creatinine, aspartate aminotransferase, total bilirubin, and anticonvulsant serum levels. Anticonvulsant exposure was determined by the presence of detectable serum levels. Cases of procarbazine hypersensitivity reactions were identified through a review of progress notes.
Results
There were 20 patients with procarbazine hypersensitivity reactions. A significant association between the exposure to anticonvulsants and the development of procarbazine hypersensitivity reactions was found (p = 0.05). In addition, there was a significant dose‐response association between the development of procarbazine hypersensitivity and the presence of therapeutic anticonvulsant serum levels (p = 0.03).
Conclusions
Concomitant exposure to anticonvulsants is associated with procarbazine hypersensitivity reactions, possibly though a reactive intermediate generated by CYP3A isoform induction. All patients in this cohort received enzyme‐inducing anticonvulsants. New anticonvulsants devoid of this property are available. These data support trials that use these newer agents for the prophylaxis of seizures in patients with brain tumors who are to receive procarbazine.
Clinical Pharmacology & Therapeutics (1997) 62, 225–229; doi:
We have isolated UV light-induced and spontaneous tumors along with nonmalignant cells and tissues from each host. CD8+ CTL clones generated to a number of highly immunogenic UV-induced tumors did ...not react with autologous normal fibroblasts nor with autologous second tumors. Using up to 25 independently induced tumors as targets, these CTL clones were found to be uniquely specific for the particular tumor used for immunization even when multiple tumors isolated from the same animals were used as targets. In addition to this extensive antigenic diversity of independently induced tumors, we found that a single cancer cell can express multiple independent antigens that were uniquely expressed on the tumor but were not detectable on autologous nonmalignant fibroblasts. A poorly immunogenic spontaneous tumor was also found to express an antigen that was uniquely specific for the immunizing tumor in that it was absent from any of 25 other tumors tested. This antigen was recognized by a mAb and not detected on autologous nonmalignant fibroblasts or on an autologous second spontaneous tumor. These findings demonstrate that syngeneic CTL clones or mAbs can define unique antigens on UV-induced or spontaneous tumors. The use of autologous nonmalignant fibroblast targets made it unlikely that these antigens were widely expressed on normal cells. The availability of cloned immunological probes to antigens on tumors isolated with autologous normal cells will allow a reliable identification of the genetic origins of unique antigens on experimentally induced and spontaneous tumors and permit a decisive answer to whether these unique antigens are encoded by normal genes or by genes that have undergone somatic mutations; i.e., whether these antigens are truly tumor specific.
Neuropeptide-FMRFamide-like immunoreactivity was characterized in the fruit fly, Drosophila melanogaster. In the adult central nervous system, a stereotypic pattern of immunoreactive cell bodies and ...immunoreactive nerve processes and varicosities was observed, indicating a neurochemical role for FMRFamide-like substance(s) in Drosophila. Localization of immunoreactivity in the central nervous system of early larval stage revealed that the majority of the prominent FMRFamide-like immunoreactive neurons were already differentiated. The FMRFamide-like immunoreactive neurons remain immunoreactive throughout postembryonic stage and persist in the adult central nervous system. In the larva, in addition to the central nervous system, FMRFamide-like immunoreactivity was localized in the fibers innervating the ring gland, in the ganglion innervating the gut and in the gastric caeca.
LUX-ZEPLIN (LZ) is a second-generation direct dark matter experiment with spin-independent WIMP-nucleon scattering sensitivity above \(1.4 \times 10^{-48}\) cm\(^{2}\) for a WIMP mass of 40 ...GeV/c\(^{2}\) and a 1000 d exposure. LZ achieves this sensitivity through a combination of a large 5.6 t fiducial volume, active inner and outer veto systems, and radio-pure construction using materials with inherently low radioactivity content. The LZ collaboration performed an extensive radioassay campaign over a period of six years to inform material selection for construction and provide an input to the experimental background model against which any possible signal excess may be evaluated. The campaign and its results are described in this paper. We present assays of dust and radon daughters depositing on the surface of components as well as cleanliness controls necessary to maintain background expectations through detector construction and assembly. Finally, examples from the campaign to highlight fixed contaminant radioassays for the LZ photomultiplier tubes, quality control and quality assurance procedures through fabrication, radon emanation measurements of major sub-systems, and bespoke detector systems to assay scintillator are presented.
The rejection of murine UV-induced skin cancers by normal mice is a striking example of powerful immune surveillance of the normal host against malignant cells. In this study, we show that UV-induced ...regressor tumors regularly grew progressively and killed mice that were depleted of CD8+ T-cells. Depletion of CD4+ T-cells had no effect, suggesting that CD8+ but not CD4+ T-cells were required for this immune surveillance. To determine whether change in major histocompatibility complex (MHC) class I expression was a frequent event that caused low immunogenicity of tumors or facilitated escape from immune destruction, recently isolated murine tumors of varying degrees of immunogenicity, including highly immunogenic UV-induced regressor, less immunogenic UV-induced progressor, and poorly immunogenic spontaneous progressor tumors, were compared. There was no correlation between the ability of a tumor to grow progressively in a normal immunocompetent host and the level of constitutive class I expression or the level of expression induced in vitro by gamma interferon. (Only 1 of more than 20 progressor tumors analyzed showed complete loss of a MHC class I molecule.) Some progressor variants showed loss of a unique tumor-specific cytotoxic T-lymphocyte-defined antigen, consistent with earlier evidence of antigen loss providing a mechanism for tumor escape. However, most of the host-selected progressor variants retained both MHC class I antigens and the unique tumor antigens that we could detect with cytotoxic T-lymphocyte clones, suggesting that mechanisms other than loss of MHC class I or of the unique target antigen may be involved in escape of some tumors from a highly effective CD8-dependent host surveillance.
We describe the design and assembly of the LUX-ZEPLIN experiment, a direct detection search for cosmic WIMP dark matter particles. The centerpiece of the experiment is a large liquid xenon time ...projection chamber sensitive to low energy nuclear recoils. Rejection of backgrounds is enhanced by a Xe skin veto detector and by a liquid scintillator Outer Detector loaded with gadolinium for efficient neutron capture and tagging. LZ is located in the Davis Cavern at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. We describe the major subsystems of the experiment and its key design features and requirements.
The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a detector containing a total of 10 tonnes of liquid xenon within a double-vessel cryostat. The large mass and ...proximity of the cryostat to the active detector volume demand the use of material with extremely low intrinsic radioactivity. We report on the radioassay campaign conducted to identify suitable metals, the determination of factors limiting radiopure production, and the selection of titanium for construction of the LZ cryostat and other detector components. This titanium has been measured with activities of \(^{238}\)U\(_{e}\)~\(<\)1.6~mBq/kg, \(^{238}\)U\(_{l}\)~\(<\)0.09~mBq/kg, \(^{232}\)Th\(_{e}\)~\(=0.28\pm 0.03\)~mBq/kg, \(^{232}\)Th\(_{l}\)~\(=0.25\pm 0.02\)~mBq/kg, \(^{40}\)K~\(<\)0.54~mBq/kg, and \(^{60}\)Co~\(<\)0.02~mBq/kg (68\% CL). Such low intrinsic activities, which are some of the lowest ever reported for titanium, enable its use for future dark matter and other rare event searches. Monte Carlo simulations have been performed to assess the expected background contribution from the LZ cryostat with this radioactivity. In 1,000 days of WIMP search exposure of a 5.6-tonne fiducial mass, the cryostat will contribute only a mean background of \(0.160\pm0.001\)(stat)\(\pm0.030\)(sys) counts.
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