Silicon tracking detectors
Controllare la nuova introduzione di Mike e richiamarla, come si potrebbe fare con l’introduzione attuale del draft, dove c’e’ gia’ la definizione di Stage I e Stage II e qualcosa sul tracking
The key requirements for the HPS tracking system are:
• To track efficiently as close as possible to the sensor’s physical edge.
• To have extreme radiation hardness. A design figure equivalent to or better than thevertex systems used for ATLAS or CMS will be required, i.e. better than 10151-MeVequivalent neutrons per cm2.
• To operate at the highest LHC luminosity and be robust and reliable.
Tracking detectors for Stage I
–Ready for installation in 2013/2014
–Four stations (2x2) at 240 m from IP5
–If Resolution per plane ~50 μm (??)is sufficient:
–Use as much as possible parts from CMS pixel detector (sensor, ROC, optical links, DAQ etc)
–Each station has 2x4 (or 2x3) pixel planes covering roughly 1.6 cm x 3.2(2.4) cm controllare
The tracking detectors in Stage One will be based on the (barrel) pixel detectors. Each stationwill consist of four or five planes, where each 8 mm × 32 mm plane is readout by four PSI46ROCs. Each tracker station will be enclosed in a box with secondary vacuum, and will becooled by Peltier elements. The corresponding DAQ system will be just another branch of thepresent pixel DAQ system, with about 300 m optical links, in place of about 100 m long fibersin use now
–Would like to avoid large dead area near pocket window
-replace first sensor near pocket window with a 3D, still using PSI46ROC
-use edgeless planar sensors (VTT)
-use slim edge planar sensors (Sintef – Gino Bolla)
3Ds have the advantages of being edgeless or active-edge and being radiation hard (citare qualcosa
+ una breve introduzione sulla tecnologia 3D)
3D sensors compatible with the CMS pixel chipPSI46 [?] have been first produced at SINTEF (Norway) as a joint effort amongst ATLAS, CMSand Medipix [?]. More CMS-compatible sensors have been and are being fabricated at FBK-IRST (Trento, Italy) and CMN (Barcelona, Spain) (trovare il modo di dar credito a tutti, ATLAS e INFN-GF). Part of theplanning and the testing is being (and will be) carried out together with the CMS pixel upgradegroup, which is also exploring this novel technology.
Sensors with 3 different electrode’s configuration have been produced so far (1E, 2E and 4E).
A number of sensors has been tested in laboratory and in test beams at Fermilab during the last year.
(contare i differenti sensori testati)
Measurements in laboratory include:
In the test beams data have been collected to measure
Few sensors were sent to be irradiated at … and then tested again.
Data are being analysed
8200 A.7.2 Stage Two detectors
8201 In order to detect at 420mfrom the IP protons from the production of central systems of masses
8202 " 100 GeV/c2, the detector edge has to approach the beam axis to a minimum distance of
8203 5 mm. This represents a challenge for the radiation hardness and radio-frequency pick-up in
8204 the detector and the nearby front-end electronics, as described in Sections A.4 and A.6. The
8205 detector system has to be robust, and for satisfactory control of systematic uncertainties its
8206 position has to be aligned and maintained to a positional accuracy of 10 μm in order to achieve
8207 the required track angular precision of 1μrad.
With a typical LHC 8208 beam size at 420 m of #beam 300 μm, the window surface of the Hamburg
8209 pipe can theoretically safely approach the beam to 15 × #beam4.5 mm. However, this distance
8210 will ultimately be determined by the LHC collimator settings, since for beam 2 in particular
8211 the halo can extend to " 5 mm with the nominal collimator positions. The window itself
8212 adds another 0.2 mm to the minimum possible distance of the detectors from the beam. To
8213 maximise the acceptance for low momentum-loss protons, the detectors should therefore be
8214 active as close to their physical edge as possible. In general, planar silicon detectors have a
8215 wide (0.25 mm – 1 mm) insensitive border region around the sensitive area which is occupied
8216 by a sequence of guard rings. This ring structure controls the potential distribution between
8217 the detectors sensitive area and the cut edge to remove leakage current. Planar silicon detectors
8218 designed for a heavy radiation environment or generally for operation at high bias voltages,
8219 contain multi-ring structures with typically about "20 rings.
8226 • Individual detectors should have a spatial precision of "10 microns. The tracking
8227 system angular precision should be 1 μrad.
8228 • At 420 m the tracking detector needs to cover an area of 25 mm x 5 mm.
8229 3D silicon technology has been chosen as the baseline detector technology best equipped to
8230 meet the above requirements. Until recently, 3D detectors have been operated only withATLAS
8231 readout electronics [? ]. A first production of 3D sensors compatible with the CMS pixel chip
8232 PSI46 [? ] has been completed at SINTEF (Norway) as a joint effort amongst ATLAS, CMS,
8233 and Medipix [? ]. More CMS-compatible sensors are being fabricated at IRST (Trento, Italy),
8234 SINTEF, and CMN (Barcelona, Spain) and will become available in the next months. Part of the
8235 planning and the testing is being (and will be) carried out together with the CMS pixel upgrade
8236 group, which is also exploring this novel technology.
8237 In a test beam at Fermilab in March 2010, two 3D sensors from SINTEF were successfully tested.
8238 One of them was tested in conjunction with the timing detectors. Since then, two more 3D
8239 sensors have been assembled and tested in the laboratory. A collected charge of about 24K
8240 electrons was measured, approximately what is expected for a 280 m thick silicon detector.
8241 Full charge collection was obtained at 40V.