| 1. |
- Collins, P., et al.
(författare)
-
The LHCb VELO upgrade
- 2011
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 636, s. S185-S193
-
Tidskriftsartikel (refereegranskat)abstract
- The LHCb experiment at the LHC plans to massively increase its data taking capabilities by running at a higher luminosity with a fully upgraded detector around 2016. This scheme is independent of (but compatible with) the plans for the SLHC upgrades. The silicon detector will be upgraded to provide a 40 MHz readout and to be able to cope with the increased radiation environment. This paper describes the options currently under consideration. A highlight of the R&D so far undertaken is a beam test during summer 2009 using the Timepix chip to track charged particles. Preliminary results are presented, including a measurement of the resolution achieved by the 55 mu m pitch pixel array of better than 9.5 mu m for perpendicular tracks and 55 mu m for angled tracks.
|
|
| 2. |
- Wong, Winnie S, et al.
(författare)
-
Electrical measurements of a multi-mode hybrid pixel detector ASIC for radiation detection
- 2012
-
Ingår i: Journal of Instrumentation. - 1748-0221. ; 7:1, s. Art. no. C01056-
-
Tidskriftsartikel (refereegranskat)abstract
- We present the first electrical measurements of an application-specific integrated circuit (ASIC) to be used in a hybrid pixel detector intended for dosimetry and radiation detection. The dosimeter has three programmable modes of operation: photon counting mode, energy integration mode, and dosimetry mode. The ASIC comprises a matrix of 16 by 16 (256 total) square pixels of 220 ÎŒm pitch, providing 12.4 mm 2 of segmented active area. Each pixel can be configured to operate in one of the three radiation measurement modes, with programmable-depth counters and shift registers to tailor the data word size and optimise the readout frame-rate in a given mode. The individual energies of impinging photons are determined through programmable analogue energy threshold discrimination, time over threshold measurement, or a combination thereof. Furthermore, the dosimetry mode contains 16 digital energy thresholds and automatically sorts data into 16 corresponding energy bin registers. The chip's output is therefore pre-processed charge spectra of the radiation field. This paper discusses results from measurements taken using programmable test-pulses to inject controlled stimuli into the pixel circuits.
|
|
| 3. |
|
|
| 4. |
- Campbell, M., et al.
(författare)
-
Towards a new generation of pixel detector readout chips
- 2016
-
Ingår i: Journal of Instrumentation. - 1748-0221. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- The Medipix3 Collaboration has broken new ground in spectroscopic X-ray imaging and in single particle detection and tracking. This paper will review briefly the performance and limitations of the present generation of pixel detector readout chips developed by the Collaboration. Through Silicon Via technology has the potential to provide a significant improvement in the tile-ability and more flexibility in the choice of readout architecture. This has been explored in the context of 3 projects with CEA-LETI using Medipix3 and Timepix3 wafers. The next generation of chips will aim to provide improved spectroscopic imaging performance at rates compatible with human CT. It will also aim to provide full spectroscopic images with unprecedented energy and spatial resolution. Some of the opportunities and challenges posed by moving to a more dense CMOS process will be discussed.
|
|
| 5. |
- Fröjdh, Erik, et al.
(författare)
-
Timepix3 : first measurements and characterization of a hybrid-pixel detector working in event driven mode
- 2015
-
Ingår i: Journal of Instrumentation. - 1748-0221. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Timepix3 is a hybrid pixel detector readout chip. It features a data driven readout mode where the chip sends out a data packet containing pixel coordinate, time over threshold and time of arrival immediately after the hit is processed by the pixel. The maximum hit rate is 40 Mhits/cm(2)/s with a minimum time step in the arrival time measurement of 1.56 ns. The pixel matrix consist of 256 x 256 square pixels at a 55 m m pitch and the pixel front end noise is 61 e(-) RMS. In this paper we present the first radiation measurements with Timepix3 bump bonded to a 300 m m thick silicon sensor. The chip is calibrated per pixel, using internal test pulses and the calibration is verified using X-ray fluorescence. The energy resolution, threshold dispersion and gain dispersion is measured. The energy resolution in time over threshold mode under normal operation conditions is 4.07 keV FWHM at 59.5 keV. At 10.5 keV an energy resolution of 0.72 keV FWHM was achieved in photon counting mode and in time over threshold mode, by optimizing the energy response, we achieved a 1.38 keV FWHM. We also investigate the time walk and present first results on using the time information for track reconstruction.
|
|
| 6. |
- Pirttiniemi, P, et al.
(författare)
-
Dental maturation in children with shunt-treated hydrocephalus
- 2004
-
Ingår i: The Cleft palate-craniofacial journal : official publication of the American Cleft Palate-Craniofacial Association. - : SAGE Publications. - 1055-6656. ; 41:6, s. 651-654
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to examine the relationship between dental maturation and somatic development and to discover their possible deviations in children with shunt-treated hydrocephalus. Design Radiographs (orthopantomogram and hand-wrist radiograph) from children with shunt-treated hydrocephalus were analyzed with respect to the dental maturation and compared with values of an age- and sex-matched control group and population standards. Patients Forty-one children with shunt-treated hydrocephalus (27 boys and 14 girls) aged from 5 to 16 years (median age 11.0 years). Results The mean deviation of dental age from chronological age was significantly greater in the hydrocephalic group than in the control group. The mean value of dental age deviation was advanced in early pubertal stages but reduced in later pubertal stages. Conclusions These findings can be explained by changes in the endocrinological conditions, which are due to disturbed pituitary secretion. The present results could also partly reflect an adaptable developmental pathway in an otherwise strictly genetically determined process.
|
|
