| 1. |
|
|
| 2. |
- Abat, E., et al.
(författare)
-
The ATLAS TRT end-cap detectors
- 2008
-
Ingår i: Journal of Instrumentation. - 1748-0221. ; 3
-
Tidskriftsartikel (refereegranskat)abstract
- The ATLAS TRT end-cap is a tracking drift chamber using 245,760 individual tubular drift tubes. It is a part of the TRT tracker which consist of the barrel and two end-caps. The TRT end-caps cover the forward and backward pseudo-rapidity region 1.0 < vertical bar eta vertical bar < 2.0, while the TRT barrel central eta region vertical bar eta vertical bar < 1.0. The TRT system provides a combination of continuous tracking with many measurements in individual drift tubes ( or straws) and of electron identification based on transition radiation from fibers or foils interleaved between the straws themselves. Along with other two sub-systems, namely the Pixel detector and Semi Conductor Tracker (SCT), the TRT constitutes the ATLAS Inner Detector. This paper describes the recently completed and installed TRT end-cap detectors, their design, assembly, integration and the acceptance tests applied during the construction.
|
|
| 3. |
- Moortgat-Pick, G., et al.
(författare)
-
Polarized positrons and electrons at the linear collider
- 2008
-
Ingår i: Physics reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 460:4-5, s. 131-243
-
Forskningsöversikt (refereegranskat)abstract
- The proposed International Linear Collider (ILC) is well-suited for discovering physics beyond the Standard Model and for precisely unraveling the structure of the underlying physics. The physics return can be maximized by the use of polarized beams. This report shows the paramount role of polarized beams and summarizes the benefits obtained from polarizing the positron beam, as well as the electron beam. The physics case for this option is illustrated explicitly by analyzing reference reactions in different physics scenarios. The results show that positron polarization, combined with the clean experimental environment provided by the linear collider, allows to improve strongly the potential of searches for new particles and the identification of their dynamics, which opens the road to resolve shortcomings of the Standard Model. The report also presents an overview of possible designs for polarizing both beams at the ILC, as well as for measuring their polarization.
|
|
| 4. |
- Gogova, D., et al.
(författare)
-
Optical and structural studies of high-quality bulk-like GaN grown by HVPE on a MOVPE AlN buffer layer
- 2006
-
Ingår i: Semiconductor Science and Technology. - : IOP Publishing. - 0268-1242 .- 1361-6641. ; 21:5, s. 702-708
-
Tidskriftsartikel (refereegranskat)abstract
- High-quality 400 ?m thick GaN has been grown by hydride vapour phase epitaxy (HVPE) on (0 0 0 1) sapphire with a 2 ?m thick AlN buffer layer. The material's crystalline quality and homogeneity was verified by x-ray diffraction (XRD), low-temperature photoluminesence (LT-PL) and LT cathodoluminescence. Plan-view transmission electron microscopy images reveal a low dislocation density of ~1.25 × 107 cm-2. The residual stress of the material was studied by two complementary techniques. LT-PL spectra show the main neutral donor bound exciton line at 3.4720 eV. This line position suggests virtually strain-free material with a high crystalline quality as indicated by the small full width at half maximum value of 0.78 meV. The presence of well resolved A- and B-free excitons in the LT-PL spectra and the absence of a yellow luminescence band prove the high quality of the HVPE-GaN in terms of purity and crystallinity. These findings are consistent with the XRD results, implying the high crystalline quality of the material grown. Hence, the material studied is well suited as a lattice parameter and thermal-expansion- coefficient matched substrate for further homoepitaxy, as needed for high-quality III-nitride device applications. Strain-free homoepitaxy on native substrates is needed to decrease considerably the defect density and in that way an improvement of the device's performance and lifetime can be achieved. © 2006 IOP Publishing Ltd.
|
|
