Measurements with a CMOS pixel sensor in magnetic fields de Boer, W; Bartsch, V; Bol, J ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2002, Letnik:
487, Številka:
1
Journal Article
Recenzirano
CMOS technique, which is the standard process used by most of the semiconductor factories worldwide, allows the production of both cheap and highly integrated sensors. The prototypes MIMOSA
1
1
...MIMOSA: Minimum Ionizing particle MOS Active pixel sensor.
-I and MIMOSA-II were designed by the IReS–LEPSI collaboration in order to investigate the potential of this new technique for charged particle tracking (Design and Testing of Monolithic Active Pixel Sensors for Charged Particle Tracking, LEPSI, IN2P3, Strasbourg, France). For this purpose it is necessary to study the effects of magnetic fields as they appear in high-energy physics on these sensors.
Real-time dosimetry is a critical issue in most radiotherapy applications. Silicon Ultra fast Cameras for electron and gamma sources In Medical Applications (SUCIMA) is a project addressing the ...development of an imaging system of extended radioactive sources based on monolithic and hybrid position-sensitive silicon sensors, where “imaging” has to be intended as the record of a dose map. The detector characteristics are constrained by the main applications, namely brachytherapy and real-time monitoring of a hadron beam for oncology. The key issues in the sensor and DAQ development are described together with the most relevant medical applications. SUCIMA
1
1
E.C. Contract No. G1RD-CT-2001-00561.
is a project approved by the EC within the V Framework Program.
Future experiments are using silicon detectors in a high radiation environment and in high magnetic fields. The radiation tolerance of silicon improves by cooling it to temperatures of approximately
...130
K
. Charge carriers generated in silicon by traversing particles are deflected due to the Lorentz force. We present measurements of the Lorentz angle in irradiated silicon detectors between 77 and
300
K
. These results and the ones obtained from non-irradiated detectors are compared with simulations.
The CMS tracker control system Dierlamm, A; Dirkes, G H; Fahrer, M ...
Journal of physics. Conference series,
07/2008, Letnik:
119, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The Tracker Control System (TCS) is a distributed control software to operate about 2000 power supplies for the silicon modules of the CMS Tracker and monitor its environmental sensors. TCS must thus ...be able to handle about 104 power supply parameters, about 103 environmental probes from the Programmable Logic Controllers of the Tracker Safety System (TSS), about 105 parameters read via DAQ from the DCUs in all front end hybrids and from CCUs in all control groups. TCS is built on top of an industrial SCADA program (PVSS) extended with a framework developed at CERN (JCOP) and used by all LHC experiments. The logical partitioning of the detector is reflected in the hierarchical structure of the TCS, where commands move down to the individual hardware devices, while states are reported up to the root which is interfaced to the broader CMS control system. The system computes and continuously monitors the mean and maximum values of critical parameters and updates the percentage of currently operating hardware. Automatic procedures switch off selected parts of the detector using detailed granularity and avoiding widespread TSS intervention.
As a result of the high luminosity phase of the SLHC, for CMS a tracking system with very high granularity is mandatory and the sensors will have to withstand an extreme radiation environment of up ...to 10
16
part/
2. On this basis, a new geometry with silicon short strip sensors (strixels) is proposed. To understand their performances, test geometries are developed whose parameters can be verified and optimized using simulation of semiconductor structures. We have used the TCAD-ISE (SYNOPSYS package) software in order to simulate the main electrical parameters of different strip geometries, for p-in-n-type wafers.
The high-luminosity upgrade of the LHC brings unprecedented requirements for real-time and precision bunch-by-bunch online luminosity measurement and beam-induced background monitoring. A key ...component of the CMS Beam Radiation, Instrumentation and Luminosity system is a stand-alone luminometer, the Fast Beam Condition Monitor (FBCM), which is fully independent from the CMS central trigger and data acquisition services and able to operate at all times with a triggerless readout. FBCM utilizes a dedicated front-end application-specific integrated circuit (ASIC) to amplify the signals from CO\(_2\)-cooled silicon-pad sensors with a timing resolution of a few nanoseconds, which enables the measurement of the beam-induced background. FBCM uses a modular design with two half-disks of twelve modules at each end of CMS, with four service modules placed close to the outer edge to reduce radiation-induced aging. The electronics system design adapts several components from the CMS Tracker for power, control and read-out functionalities. The dedicated FBCM23 ASIC contains six channels and adjustable shaping time to optimize the noise with regards to sensor leakage current. Each ASIC channel outputs a single binary high-speed asynchronous signal carrying time-of-arrival and time-over-threshold information. The chip output signal is digitized, encoded and sent via a radiation-hard gigabit transceiver and an optical link to the back-end electronics for analysis. This paper reports on the updated design of the FBCM detector and the ongoing testing program.
Cryogenic Si detectors for ultra radiation hardness in SLHC environment Li, Zheng; Abreu, M.; Anbinderis, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2007, Letnik:
579, Številka:
2
Journal Article
Recenzirano
Radiation hardness up to 10
16
n
eq/cm
2 is required in the future HEP experiments for most inner detectors. However, 10
16
n
eq/cm
2 fluence is well beyond the radiation tolerance of even the most ...advanced semiconductor detectors fabricated by commonly adopted technologies: the carrier trapping will limit the charge collection depth to an effective range of 20–30
μm regardless of depletion depth. Significant improvement of the radiation hardness of silicon sensors has been taken place within RD39. Fortunately the cryogenic tool we have been using provides us a convenient way to solve the detector charge collection efficiency (CCE) problem at SLHC radiation level (10
16
n
eq/cm
2). There are two key approaches in our efforts: (1) use of the charge/current injection to manipulate the detector internal electric field in such a way that it can be depleted at a modest bias voltage at cryogenic temperature range (⩽230
K); and (2) freezing out of the trapping centers that affects the CCE at cryogenic temperatures lower than that of the LN
2 temperature.
In our first approach, we have developed the advanced radiation hard detectors using charge or current injection, the current injected diodes (CID). In a CID, the electric field is controlled by injected current, which is limited by the space charge, yielding a nearly uniform electric field in the detector, independent of the radiation fluence. In our second approach, we have developed models of radiation-induced trapping levels and the physics of their freezing out at cryogenic temperatures. In this approach, we intend to study the trapping effect at temperatures below LN
2 temperature. A freeze-out of trapping can certainly help in the development of ultra-radiation hard Si detectors for SLHC. A detector CCE measurement system using ultra-fast picosecond laser with a He cryostat has been built at CERN. This system can be used to find out the practical cryogenic temperature range that can be used to freeze out the radiation-induced trapping levels, and it is ready for measurements on extremely heavily irradiated silicon detectors. Initial data from this system will be presented.
CERN RD39 Collaboration develops radiation-hard cryogenic silicon detectors. Recently, we have demonstrated improved radiation hardness in novel Current Injected Detectors (CID). For detector ...characterization, we have applied cryogenic Transient Current Technique (C-TCT). In beam tests, heavily irradiated CID detector showed capability for particle detection. Our results show that the CID detectors are operational at the temperature -50degC after the fluence of 1 times 10 16 1 MeV neutron equivalent/cm 2 .
There are two key approaches in our CERN RD 39 Collaboration efforts to obtain ultra-radiation-hard Si detectors: (1) use of the charge/current injection to manipulate the detector internal electric ...field in such a way that it can be depleted at a modest bias voltage at cryogenic temperature range (⩽150
K), and (2) freezing out of the trapping centers that affects the CCE at cryogenic temperatures lower than that of the liquid nitrogen (LN
2) temperature.
In our first approach, we have developed the advanced radiation hard detectors using charge or current injection, the current injected diodes (CID). In a CID, the electric field is controlled by injected current, which is limited by the space charge, yielding a nearly uniform electric field in the detector, independent of the radiation fluence. In our second approach, we have developed models of radiation-induced trapping levels and the physics of their freezing out at cryogenic temperatures.
The recovery of the charge collection efficiency (CCE) at low temperatures, the so-called ”Lazarus effect”, was studied in Si detectors irradiated by fast reactor neutrons, by protons of medium and ...high energy, by pions and by gamma-rays. The experimental results show that the Lazarus effect is observed: (a) after all types of irradiation; (b) before and after space charge sign inversion; (c) only in detectors that are biased at voltages resulting in partial depletion at room temperature. The experimental temperature dependence of the CCE for proton-irradiated detectors shows non-monotonic behaviour with a maximum at a temperature defined as the CCE recovery temperature. The model of the effect for proton-irradiated detectors agrees well with that developed earlier for detectors irradiated by neutrons. The same midgap acceptor-type and donor-type levels are responsible for the Lazarus effect in detectors irradiated by neutrons and by protons. A new, abnormal “zigzag”-shaped temperature dependence of the CCE was observed for detectors irradiated by all particles (neutrons, protons and pions) and by an ultra-high dose of γ-rays, when operating at low bias voltages. This effect is explained in the framework of the double-peak electric field distribution model for heavily irradiated detectors. The redistribution of the space charge region depth between the depleted regions adjacent to p+ and n+ contacts is responsible for the “zigzag”- shaped curves. It is shown that the CCE recovery temperature increases with reverse bias in all detectors, regardless of the type of radiation.
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