Charge collection efficiency studies with irradiated silicon detectors Allport, P.P.; Bowcock, T.J.V.; Casse, G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2003, Letnik:
501, Številka:
1
Journal Article
Recenzirano
Small area
(1×1
cm
2)
microstrip detectors, made with a p
+-n diode structure on FZ silicon substrates, both with and without oxygen enrichment, have been irradiated with
24
GeV/c
protons to fluences ...of 1.9, 2.9 and
5.1×10
14
p/cm
2
. Their charge collection properties have been studied using a
106
Ru
beta-source with a wide bandwidth current amplifier and compared with those for a non-irradiated device. The integrated charge collected at different times (10, 25, 40 and
80
ns
) has been used to estimate the effect of ballistic deficit. Predictions for the reduction in charge collection efficiency expected at fluences as high as
10
15
cm
−2
are presented using a parameterization described in earlier work which also fits this data well.
Silicon sensors will probably be the choice for the inner tracker detectors of the experiments in the anticipated LHC luminosity upgrade (Super LHC, SLHC). These sensors will have to survive a ...radiation environment almost an order of magnitude higher than within the already challenging LHC trackers. The final cumulated fluence will depend on the integrated luminosity targeted by the experiments, but an increase of a factor of 5–10 is expected. A significant contribution to the radiation damage of the sensors in the tracker volume is due to backscattered neutrons. Simulations show that the neutron flux equals the charged particle flux emerging from the interactions at a radial distance of about 25
cm from the beam axis. Irradiation with neutrons are therefore a necessary test for proving the ability of prototype silicon detectors to survive the SLHC fluences. Short strip microstrip detectors made on p-type silicon substrate for optimised radiation hardness have been irradiated with fast neutrons to various fluences up to
3
×
10
15
cm
-
2
. They have been characterised in term of charge collection efficiency with LHC speed electronics (40
MHz). The results are here presented in the light of a possible upgrade scenario of the ATLAS tracker.
The planned High Luminosity Large Hadron Collider is being designed to maximise the physics potential of the LHC with 10 years of operation at instantaneous luminosities of 7.5×1034cm−2s−1. A ...consequence of this increased luminosity is the expected radiation damage requiring the tracking detectors to withstand hadron fluence to over 1×1015 1 MeV neutron equivalent per cm2 in the ATLAS Strips system. Fast readout electronics, deploying 130 nm CMOS front-end electronics are glued on top of a silicon sensor to make a module. The radiation hard n-in-p micro-strip sensors used have been developed by the ATLAS ITk Strip Sensor collaboration and produced by Hamamatsu Photonics. A series of tests were performed at the DESY-II test beam facility to investigate the detailed performance of a strip module with both 2.5 cm and 5 cm length strips before irradiation. The DURANTA telescope was used to obtain a pointing resolution of 2 μm, with an additional pixel layer installed to improve timing resolution to ∼25 ns. Results show that prior to irradiation a wide range of thresholds (0.5–2.0 fC) meet the requirements of a noise occupancy less than 1×10−3 and a hit efficiency greater than 99%.
The one-pot reaction of the CFC replacement 1-chloro-2,2,2-trifluoroethane (CF
3CH
2Cl, HCFC-133a) with two equivalents of butyllithium in diethylether at −78°C followed by the addition of main group ...or transition metal halides results in good yields of the metal-chlorodifluorovinyl-containing compounds R
3Sn(CClCF
2) {R=Me, Et, Bu}, Sn(CClCF
2)
4, Sb(CClCF
2)
3, Hg(CClCF
2)
n
Cl
(2−
n)
(
n=1,2),
trans-Ni(CClCF
2)
2(PBu
3)
2,
trans-Pd(CClCF
2)
2(PBu
3)
2 and Au(CClCF
2)(PPh
3). The molecular structures of Hg(CClCF
2)Cl,
trans-Pd(CClCF
2)
2(Bu
3P)
2 and Au(CClCF
2)(PPh
3) have been obtained from single crystal data; these are the first such structural data to be reported for any chlorodifluorovinyl-containing organometallic complexes. The molecular structure of Au(CFCF
2)(PPh
3), which was prepared using a similar method based on CF
3CH
2F (HFC-134a), is also reported and compared with that of the chlorodifluorovinyl analogue.
The ABCD design is a single chip implementation of the binary readout architecture for silicon strip detectors in the ATLAS semiconductor tracker. The prototype chip has been manufactured ...successfully in the DMILL process. In the paper we present the design of the chip and the measurement results. The basic analogue performance of the ABCD design has been evaluated using a prototype SCT module equipped with the ABCD chips. The digital performance has been evaluated using a general purpose IC tester. The measurements confirmed that all blocks of the ABCD design are fully functional and the chips meet all basic requirements of the SCT. Wafer screening has been performed using a customised wafer tester.
A prototype silicon microstrip detector with p-strip read-out on oxygen enriched n-type substrate has been non-homogeneously irradiated using a 24
GeV/
c proton beam at the CERN-PS accelerator. The ...detector has a semicircular shape with radial strip geometry. The peak fluence received by the detector was 4.6×10
14
p/cm
2 though the non-uniform nature of the exposure left part of the detector unirradiated. The inhomogeneous irradiation introduced a damage profile in the detector approximating to that expected in the inner LHC region. High-irradiation gradients are important to study as they can modify the electric field within the silicon. Of special interest are changes in the component of the electric field parallel to the strip plane but perpendicular to the strips, which could lead to systematic shifts in the reconstructed cluster position. If these (flux and position dependent) shifts are sufficiently large they could contribute to degrading the spatial resolution of the detector. In order to quantify these effects, a precision narrow focus light spot from an infrared laser was used to investigate the charge collection properties of the sensor. Particular attention was devoted to the regions where a high gradient of the fluence will have introduced a large gradient in the effective local space charge. The results reported below place limits on the ‘distortions’ due to non-uniform irradiation.
To increase equity and inclusion for underserved and excluded Indigenous students, we must make efforts to mitigate the unique barriers they face. As their knowledge systems have been historically ...excluded and erased in Western science, we begin by reviewing the literature on the inclusion of Traditional Ecological Knowledge (TEK) in biology education and describe best practices. Next, to better understand how Native Hawaiian and other Pacific Islander (NHPI) students integrate into the scientific community, we used Social Influence Theory as a framework to measure NHPI student science identity, self-efficacy, alignment with science values, and belonging. We also investigated how students feel their ethnic and science identities interact. We found that NHPI students do not significantly differ from non-NHPI students in these measures of integration, and that NHPI students are varied in how they perceive their ethnic and science identities interact. Some students experience conflict between the two identities, while others view the two as having a strengthening relationship. Next, we describe a lesson plan created to include Hawaiian TEK in a biology class using best practices described in the literature. This is followed by an empirical study on how students were impacted by this lesson. We measured student integration into the science community using science identity, selfefficacy, alignment with science values, and belonging. We found no significant differences between NHPI and non-NHPI students. We also looked at student participation, and found that all students participated more on intervention days involving TEK and other ways of knowing than on non-intervention days. Finally, we describe qualitative findings on how students were impacted by the TEK interventions. We found students were predominantly positively impacted by the inclusion of TEK and discuss future adjustments that could be made using their recommendations.The last chapter describes how we used remote sensing to investigate land cover in a fenced and unfenced region of the Koʻolau Mountains on the island of Oʻahu. After mapping the biodiversity hotspot Management Unit of Koloa, we found that there is slighlty more bare ground, grass, and bare ground/low vegetation mix in fenced, and thereby ungulate-free areas, than those that were unfenced and had ungulates. This could be indicative of faster growing species recolonizing after ungulate removal, but further research is needed. Implications of these findings and suggestions for future research are discussed.
The ALIBAVA is a compact and portable system for characterization of silicon microstrip radiation detectors. Actually, the ALIBAVA system is conceived to easily characterize multichannel ...semiconductor detectors, providing high sensitivity to low signals and high speed. The front-end electronics is based on a low noise ASIC with 128 input channels. Beyond its scientific and sensor R&D applications, the system can also be used in instrumentation lectures at the university teaching laboratories. New features of the system makes it more suitable for its handling by undergraduate and postgraduate students, who will greatly benefit in their instruction by using this system to learn about the properties of microstrip sensors and signal formation in those devices.
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