Aging in large CDF tracking chambers Binkley, M.; Wagner, R.L.; Mukherjee, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2003, Letnik:
515, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The experience of the Collider Detector at Fermilab (CDF) with aging in the large axial drift chamber responsible for tracking in the central region is presented. Premature aging in the Run 1 chamber ...was observed after only 0.02
C/cm. After cleaning much of the gas system and making modifications to reduce aerosols from the alcohol bubbler, the observed aging rate fell dramatically in test chambers. Considerable effort has been made to better understand the factors that affect aging since the replacement chamber for Run 2 will accumulate about 1.0
C/cm. Current test chambers using the full CDF gas system show aging rates of less than 5%/C/cm.
The aim of the second part of this study was to evaluate the mechanical behaviour of 2- versus 4-plate fixation and bony structures after Le Fort I impaction surgeries using three-dimensional finite ...element analysis (3D-FEA). Two 3D-FEA models were created to fixate the impacted maxilla at the Le Fort I level as 2-plate fixation at the piriform rims (IMP-2 model) and 4-plate fixation at the zygomatic buttresses and piriform rims (IMP-4 model). The IMP-2 model contained 225664 elements and 48754 nodes and the IMP-4 model consisted of 245929 elements and 53670 nodes. The stresses in each maxillary model were computed. The models were loaded on one side, at the molar-premolar region, in vertical, horizontal and oblique directions to reflect the chewing process. It was concluded that the use of 4-plate fixation following Le Fort I advancement surgery provides fewer stress fields on the maxillary bones and fixation materials than 2-plate fixation from a mechanical point of view.
Cerebellar, hippocampal, and basal nuclei transient edema with restricted diffusion (CHANTER) syndrome is a constellation of specific imaging findings characterized by cytotoxic edema in the ...bilateral hippocampi, cerebellar cortices, and basal ganglia in patients presenting with altered mental status in the setting of substance intoxication. Previous case reports have demonstrated a strong correlation between CHANTER syndrome and polysubstance abuse, particularly with opioid intoxication. The patient we present in this case was found unresponsive following opioid use and demonstrated a constellation of findings on initial and follow-up imaging, consistent with CHANTER syndrome. While cases of irreversible brain damage or death during hospitalization have been reported in the literature, our patient demonstrated near-full recovery a few days after admission to the hospital. We aim to highlight the presentation and progression of CHANTER syndrome and alert clinicians and radiologists to include this entity in their diagnostic checklist for patients with polysubstance abuse and altered mental status.
Status of the ZEPLIN II experiment Alner, G.J.; Atac, M.; Bewick, A. ...
New astronomy reviews,
05/2005, Letnik:
49, Številka:
2
Journal Article
Recenzirano
ZEPLIN II is a 30-kg two-phase xenon detector designed for direct detection of cold dark matter in the form of WIMPs. Currently in the commissioning phase, it will begin operation in the Boulby Mine, ...UK later this year. ZEPLIN II is capable of discriminating between nuclear recoils and background events and has a design reach up to two orders of magnitude beyond current limits. It will also serve as a step in the development program for a next-generation ton-scale detector.
The characteristics of a multianode photomultiplier tube (MAPMT; Hamamatsu R5900-00-M64) with 64 anodes have been studied. We report measurements that include single photoelectron sensitivity, ...electrical and optical cross-talk, dark count, and gain variation. Environmental test results relevant to use of these devices in space are also presented. The characteristics of the MAPMT make it well suited for detection of light from scintillating fibers as well as other applications.
Beam test results of the US-CMS forward pixel detector Atac, M; Bartz, E; Bolla, G ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2002, Letnik:
488, Številka:
1
Journal Article
Recenzirano
CMS will use silicon pixel as its innermost tracking device. Prototypes of these
150
μm
square pixels bump bonded to DMILL readout chips were tested at CERN in a pion beam. A silicon telescope ...consisting of 8 planes of silicon strips was used to interpolate tracks to the position of the pixel detector. Data were taken with the beam at different angles of incidence relative to the pixel sensors. Position resolutions between 10 and
20
μm
, depending on the hit position, were observed using charge sharing for the final configuration with unirradiated detectors. The observed resolution was as expected.
We present a possible design of future large-scale dark matter detector using liquid xenon. A low energy threshold is achieved by using a large CsI-coated internal photocathode for primary light ...collection. A focusing field, in the active volume and an electron focusing structure at the liquid surface, are used to transport free-electrons to the luminescence field. A 3D reconstruction of the events can be achieved by timing and location of the luminescent signal. A liquid xenon Compton veto and self-shield are integrated in the compact design. This detector could be used to probe most of the SUSY predicted dark matter. ZEPLIN IV can be initially tested at Boulby and then be moved to the USA to operate at a US deep underground science and engineering laboratory.
The aim of this study was to compare the stability of mini-implants using drill-free and drilling methods, both before and after early force loading. Sixty-two adolescent patients (24 males and 38 ...females, mean age 15.7 ± 4.2 years) were randomly assigned to three groups and 112 titanium mini-implants were placed between the upper first molars and second premolars to achieve molar distalization. Groups I (n = 22) and II (n = 20) received pilot drilling with diameters of 1.1 and 0.9 mm, respectively, while the drill-free method was used in group III (n = 20). Distalization forces of up to 200 g were applied with nickel-titanium (NiTi) open coil springs. The Z-test was used for statistical analyses to compare the success rates of the groups with each other.
The overall success rate was 77.7 per cent. There was no significant difference between groups I and II either before or after loading. Significant differences were found between groups I and III (P = 0.0002) and between groups II and III (P = 0.045) both before and after loading. Mini-implants using the drill-free method provided the highest success rate before orthodontic force application and also maintained their stability after early loading for 1 month during orthodontic treatment. Smaller drill diameters can contribute to clinical stability of mini-implants in the short-term, however long-term evaluations are needed to clarify the stability of temporary skeletal anchorage devices throughout orthodontic loading.
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