The LUX-ZEPLIN experiment is a dark matter detector centered on a dual-phase xenon time projection chamber operating at the Sanford Underground Research Facility in Lead, South Dakota, USA. This ...Letter reports results from LUX-ZEPLIN's first search for weakly interacting massive particles (WIMPs) with an exposure of 60 live days using a fiducial mass of 5.5 t. A profile-likelihood ratio analysis shows the data to be consistent with a background-only hypothesis, setting new limits on spin-independent WIMP-nucleon, spin-dependent WIMP-neutron, and spin-dependent WIMP-proton cross sections for WIMP masses above 9 GeV/c^{2}. The most stringent limit is set for spin-independent scattering at 36 GeV/c^{2}, rejecting cross sections above 9.2×10^{-48} cm at the 90% confidence level.
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.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
1
In vivo brain microdialysis has been employed to investigate the effects of ibogaine on nicotine‐induced changes in dopamine overflow in the nucleus accumbens (NAc) of freely moving rats. The ...effects of the compound on locomotor responses to nicotine and behaviour in the elevated plus‐maze were also examined.
2
No changes were observed in the dopamine overflow or the locomotor activity of the animals following the administration of ibogaine (40 mg kg−1, i.p.). However, ibogaine, administered 22 h earlier, significantly (P<0.01) attenuated the increase in dopamine overflow but not the hyperlocomotion, evoked by nicotine.
3
In the elevated plus‐maze test, significant reductions in the open:total runway entries in both saline‐treated controls (P<0.05) and nicotine‐treated (P<0.01) rats were obtained when the animals were tested 22 h after pretreatment with ibogaine (40 mg kg−1, i.p.). The total activity was significantly (P<0.01) greater in the nicotine‐treated rats but this response was not affected by ibogaine pretreatment.
4
Administration of ibogaine was associated with reductions in the tissue levels of 5‐hydroxyindoleacetic acid (5‐HIAA) in the NAc (P<0.01) and striatum (P<0.05) and an increase in the level of this metabolite in the medial prefrontal cortex (mPFC) (P<0.01) while the levels of dopamine and 5‐hydroxytryptamine (5‐HT) in the mPFC were reduced (P<0.05). The DOPAC/dopamine (P<0.05) and 5‐HIAA/5‐HT (P<0.01) ratios were significantly increased in the mPFC for at least 7 days after a single treatment with ibogaine.
5
Ibogaine attenuates the nicotine‐induced increases in dopamine overflow in the NAc and may, therefore, inhibit the rewarding effects of this drug. However, the long lasting anxiogenesis induced by ibogaine warrant further investigation before its use could be recommended for smokers.
Commissioning Test of ATLAS End-Cap Toroidal Magnets Dudarev, A.; ten Kate, H.H.J.; Buskop, J. ...
IEEE transactions on applied superconductivity,
06/2009, Letnik:
19, Številka:
3
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
The system of superconducting toroids in the ATLAS experiment at CERN consists of three magnets. The Barrel Toroid was assembled and successfully tested in 2006. Next, two End-Cap Toroids have been ...tested on surface at 77 K and installed in the cavern, 100-m underground. The End Cap Toroids are based on Al stabilized Nb-Ti/Cu Rutherford cables, arranged in double pancake coils and conduction cooled at 4.6 K. The nominal current is 20.5 kA at 4.1 T peak field in the windings and the stored energy is 250 MJ per toroid. Prior to final testing of the entire ATLAS Toroidal system, each End Cap Toroid passed a commissioning test up to 21 kA to guarantee a reliable performance in the final assembly. In this paper the test results are described. It includes the stages of test preparation, isolation vacuum pumping and leak testing, cooling down, step-by-step charging to full current, training quenches and quench recovery. By fast discharges the quench detection and protection system was checked to demonstrate a safe energy distribution within the magnet after a quench or a triggered fast dump.
The ATLAS Experiment at LHC, CERN will utilize a large, superconducting, air-cored toroidal magnet system with a long Barrel Toroid and two End Cap Toroids. Each End Cap Toroid contains eight ...racetrack coils mounted as a single cold mass in a cryostat vessel of approximately 10 m diameter and 5 m length. The operating current is 20.5 kA at 0.25 GJ stored energy and a peak field of 4.1 T in the windings. This paper presents the status of the End Cap Toroid Project. Final integration of the two cold masses, 120 tons each, into their respective vacuum cryostats is described. The specialized techniques, procedures and tooling infrastructure required for these operations are explained. Pre-installation cooldown to 85 K is reported. Installation of the toroids in the ATLAS cavern 100 m underground will be described. The final interfacing to the Barrel Toroid and services in the cavern will be reviewed along with preparations for final test and commissioning.
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 40GeV/c2 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.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The ATLAS experiment at LHC (CERN) will utilize a large, superconducting, air-cored toroid magnet system with a long Barrel Toroid and two End Cap Toroids. Each End Cap Toroid will contain eight ...racetrack coils mounted as a single cold mass in a cryostat vessel of approximately 10 m diameter. This paper presents the design principles and realization of the cold mass assembly. The procedures for integration of the full cold mass, 120 tonnes, into the vacuum cryostat are described. The overall status of toroid magnet integration and planning for test and installation is reviewed
The present study compared high affinity neurotensin (NT) binding in rat brain following acute or chronic treatment with the classical antipsychotic, haloperidol, and the newer antipsychotic drugs, ...clozapine and zotepine.
Drugs were given orally, as an acute treatment (1 dose) or chronically (21 day dosing) and binding to the NT high affinity receptor was examined in three brain regions; striatum, nucleus accumbens/olfactory tubercle and frontal cortex.
Acute dosing with either vehicle, haloperidol, clozapine or zotepine produced no significant changes in NT binding from controls (naïve rats).
Chronic (21 day) dosing resulted in an increase in the KD and Bmax of high affinity receptors in the striatum following haloperidol, but not clozapine, zotepine or vehicles. In contrast, the newer antipsychotics, clozapine and zotepine but not haloperidol or vehicles, significantly altered NT binding in the nucleus accumbens/olfactory tubercle by decreasing the KD and Bmax.
Further differentiation between the two newer antipsychotic drugs occurred in the frontal cortex. Clozapine had no significant effect on NT binding, whereas zotepine significantly reduced the KD of the high affinity receptor with no alteration in Bmax.
The antipsychotic drugs tested did not interact directly with the NT high affinity receptor. Therefore, they must be acting indirectly via an alternative receptor mechanism to alter NT high affinity binding. In accordance with previously reported NT/dopamine receptor interactions, this would suggest cross‐talk between these systems.
Overall, these data demonstrate that chronic, but not acute, administration of antipsychotic drugs alters NT binding in the rat brain. In addition, anatomical differences in NT binding arise according to the antipsychotic drug under test. This may be predictive of drug side‐effect profile, antipsychotic efficacy or atypicality.
British Journal of Pharmacology (2000) 131, 990–996; doi:10.1038/sj.bjp.0703653
PDF
