2011

Development of a beam test telescope based on the Alibava readout system

R. Marco-Hernandez (for the Alibava Collaboration)
Journal of Instrumentation, 2011, Vol. 6 Issue 1, Article C01002
doi:10.1088/1748-0221/6/01/C01002

Abstract: A telescope for a beam test have been developed as a result of a collaboration among the University of Liverpool, Centro Nacional de Microelectrónica (CNM) of Barcelona and Instituto de Física Corpuscular (IFIC) of Valencia. This system is intended to carry out both analogue charge collection and spatial resolution measurements with different types of microstrip or pixel silicon detectors in a beam test environment. The telescope has four XY measurement as well as trigger planes (XYT board) and it can accommodate up to twelve devices under test (DUT board). The DUT board uses two ASIC chips for the readout of chilled silicon detectors. The board could operate in a self-triggering mode. The board features a temperature sensor and it can be mounted on a rotary stage. A peltier element is used for cooling the DUT. Each XYT board measures the track space points using two silicon strip detectors connected to two ASIC chips. It can also trigger on the particle tracks in the beam test. The board includes a CPLD which allows for the synchronization of the trigger signal to a common clock frequency, delaying and implementing coincidence with other XYT boards. An Alibava mother board is used to read out and to control each XYT/DUT board from a common trigger signal and a common clock signal. The Alibava board has a TDC on board to have a time stamp of each trigger. The data collected by each Alibava board is sent to a master card by means of a local data/address bus following a custom digital protocol. The master board distributes the trigger, clock and reset signals. It also merges the data streams from up to sixteen Alibava boards. The board has also a test channel for testing in a standard mode a XYT or DUT board. This board is implemented with a Xilinx development board and a custom patch board. The master board is connected with the DAQ software via 100M Ethernet. Track based alignment software has also been developed for the data obtained with the DAQ software.

Comparative measurements of highly irradiated n-in-p and p-in-n 3D silicon strip detectors
M. Köhler, R. Bates, C. Fleta, K. Jakobs, M. Lozano, C. Parkes, U. Parzefall, G. Pellegrini, J. Preiss
Nuclear Inst. & Meth. A, Vol. 659, Issue 1, 11 Dec. 2011, Pages 272-281
doi:10.1016/j.nima.2011.08.041

Abstract: Silicon detectors in 3D technology are a candidate for applications in environments requiring an extreme radiation hardness, as in the innermost layers of the detectors at the proposed High-Luminosity LHC. In 3D detectors, the electrodes are made of columns etched into the silicon perpendicular to the surface. This leads to higher electric fields, a smaller depletion voltage and a reduced trapping probability of the charge carriers compared to standard planar detectors. In this article, the signal and the noise of irradiated n-in-p and p-in-n 3D silicon strip detectors are compared. The devices under test have been irradiated up to a fluence of 2×10¹⁶ 1 MeV neutron equivalent particles per square centimetre (n_eq/cm²), which corresponds to the fluence expected for the inner pixel detector layers at the High-Luminosity LHC. A relative charge collection efficiency of approximately 70% was obtained even after the highest irradiation fluence with both detector types. The influence of different temperatures on the signal and the noise is investigated and results of annealing measurements are reported.

Campaign to identify the future CMS tracker baseline
K.-H. Hoffmann (for the CMS Tracker Sensor Working Group)
Nuclear Inst. & Meth. A, Vol. 658, Issue 1, 1 December 2011, Pages 30-35
doi:10.1016/j.nima.2011.05.028

Abstract: CMS has started a campaign to identify the future sensor technology baseline for the Tracker Upgrade Phase II. A large variety of 6-in. wafers of different thicknesses and technologies have been ordered. The sensor properties and especially the behavior after irradiation will be investigated for floatzone, magnetic Czochralski and epitaxial silicon material with dedicated test structures. The sensors come in p-in-n and n-in-p versions. The p-stop as well as p-spray isolation technologies will be explored for the n-in-p type sensors. Some additional wafers will come with an additional routing in a second metal layer on selected structures. Approximately one half of these wafers have already been delivered. Pre-qualification has just started.

Characterisation of “n-in-p” pixel sensors for high radiation environments
I. Tsurin, A. Affolder, P.P. Allport, G. Casse, V. Chmill, T. Huse, M. Wormald
Nuclear Inst. & Meth. A, Vol. 650, Issue 1, 11 September 2011, Pages 140-144
doi:10.1016/j.nima.2010.12.206

Abstract: This work presents the first held at Liverpool University measurements of pixel sensors with n-type readout implant in the p-type bulk before and after irradiation of samples by 24 GeV protons to doses 7×10¹⁵ and 1.5×10¹⁶ protons/cm². A comparison is given for two measurement techniques; one based on the FE-I3 readout chip designed for the ATLAS and the other using the ASIC chip developed for the LHCb experiments at CERN.

Measurements with Irradiated 3D Silicon Strip Detectors
M. Köhler, R. Bates, G.-F. Dalla Betta, C. Fleta, J. Härkönen, K. Jakobs, M. Lozano, T. Mäenpää, H. Moilanen, C. Parkes, U. Parzefall, G. Pellegrini, H. Sadrozinski, L. Spiegel, L. Wiik
Nuclear Physics B – Proc. Suppl., Vol. 215, Issue 1, June 2011, Pages 247-249
doi:10.1016/j.nuclphysbps.2011.04.021

Abstract: For the unprecedentedly high radiation level at the sLHC, the luminosity upgrade of the LHC, new tracking detectors are investigated. Among different approaches, silicon detectors in 3D technology constitute a promising option. Columnar electrodes are etched into the substrate, therefore the distance for charge collection and depletion is decoupled from the detector thickness. Thus, two of the detrimental effects caused by radiation in silicon (increased depletion voltage and charge carrier trapping) can be reduced. Results of measurements with irradiated 3D silicon strip detectors produced by IMB-CNM are presented.

Characterization of proton and neutron irradiated low resistivity p-on-n magnetic Czochralski ministrip sensors and diodes
N. Pacifico, I. Dolenc Kittelmann, M. Fahrer, M. Moll, O. Militaru
Nuclear Inst. & Meth. A, Vol. 658, Issue 1, 1 December 2011, Pages 55-60
doi:10.1016/j.nima.2011.03.026

Abstract: Transient Current Technique (TCT) and Charge Collection Efficiency (CCE) measurements were performed on low resistivity (280 Ω cm) n-bulk, p-readout magnetic Czochralski ministrip sensors and diodes. The detectors were irradiated with neutrons and 24 GeV/c protons up to a total NIEL equivalent fluence of 8×10¹⁵/cm². The study was addressed to assess the radiation tolerance of the detectors up to fluences expected in the next generations of High Energy Physics experiments. The charge collection efficiency after irradiation was found to be much higher than for standard FZ silicon p-in-n sensors. The underlying physics of this remarkable result was investigated by performing Edge-TCT measurements on one of the neutron irradiated ministrip sensors to extract detailed informations about the field and efficiency profiles of the detector.

Performance of thin pixel sensors irradiated up to a fluence of and development of a new interconnection technology for the upgrade of the ATLAS pixel system
A. Macchiolo, L. Andricek, M. Beimforde, H.-G. Moser, R. Nisius, R.H. Richter, P. Weigell
Nuclear Inst. & Meth. A, Vol. 650, Issue 1, 11 September 2011, Pages 145-149
doi:10.1088/1748-0221/6/11/C11022

Abstract: The electrical properties of hadron irradiated silicon detectors change over several years after irradiation. This annealing process has a strong dependence on temperature and it can be accelerated or decelerated by lowering or elevating the temperature at which the sensors are kept. This is exploited to investigate the long term behaviours of irradiated silicon detectors that are, or will be, installed in the experiment at the current and upgraded LHC at CERN. Elevated temperatures (up to 80°C) are used to accelerate the effect of annealing to study the expected changes of the sensor performances over several years of room temperature equivalent time. Low temperatures are applied to the sensors also when not operated to suppress undesired effects of annealing. The acceleration factors with respect to nominal room temperature (RT = 20°C) have been established monitoring the changes of the capacitance-voltage characteristics (CV) with time at various temperatures. In the experiments, the maximum high temperature envisaged out of operation cannot exceed much 20°C. It is important to measure the changes of the relevant parameters (charge collection reverse current, noise) at this temperature to verify the annealing behaviours in realistic conditions for planning the operation scenario (i.e. bias voltage and temperature during and outside operation) of the silicon sensors. We show here the study of room temperature annealing of the charge collection, reverse current and noise of silicon microstrip detectors after two doses of hadron irradiation (2 and 10 × 10¹⁵ n_eq cm⁻²) . These doses are chosen to represent the expected levels in the future upgrade of the LHC at CERN (High Luminosity LHC, HL-LHC) for the microstrip and pixel layers. The measurements show that a suitable choice of annealing time at 20°C can partially recover the degraded charge collection and reduce the reverse current after a given dose of hadron irradiation.

Changes of the particle detection properties of irradiated silicon microstrip sensors after room temperature annealing
G. Casse, A. Affolder, P. P. Allport, V. Chmill, D. Forshaw, A. Greenall, I. Tsurin, T. Huse
Journal of Instrumentation, 2011, vol. 6, Issue 11, Article C11022
Proceedings of the 13th International Workshop on Radiation Imaging Detectors (IWORID)
doi:10.1088/1748-0221/6/11/C11022

Abstract: The electrical properties of hadron irradiated silicon detectors change over several years after irradiation. This annealing process has a strong dependence on temperature and it can be accelerated or decelerated by lowering or elevating the temperature at which the sensors are kept. This is exploited to investigate the long term behaviours of irradiated silicon detectors that are, or will be, installed in the experiment at the current and upgraded LHC at CERN. Elevated temperatures (up to 80°C) are used to accelerate the effect of annealing to study the expected changes of the sensor performances over several years of room temperature equivalent time. Low temperatures are applied to the sensors also when not operated to suppress undesired effects of annealing. The acceleration factors with respect to nominal room temperature (RT = 20°C) have been established monitoring the changes of the capacitance-voltage characteristics (CV) with time at various temperatures. In the experiments, the maximum high temperature envisaged out of operation cannot exceed much 20°C. It is important to measure the changes of the relevant parameters (charge collection reverse current, noise) at this temperature to verify the annealing behaviours in realistic conditions for planning the operation scenario (i.e. bias voltage and temperature during and outside operation) of the silicon sensors. We show here the study of room temperature annealing of the charge collection, reverse current and noise of silicon microstrip detectors after two doses of hadron irradiation (2 and 10 × 1015 neq cm−2) . These doses are chosen to represent the expected levels in the future upgrade of the LHC at CERN (High Luminosity LHC, HL-LHC) for the microstrip and pixel layers. The measurements show that a suitable choice of annealing time at 20°C can partially recover the degraded charge collection and reduce the reverse current after a given dose of hadron irradiation.