Recent results of the 3D-stripixel Si detectors

Z. Li, D. Bassignana, W. Chen, S. Liu, D. Lynn, G. Pellegrini

Nuc. Instr. Meth. A, Volume 765, 21 November 2014, Pages 103–108

Abstract: The design, fabrication process and the characteristics measurements of the new 3D-stripixel detectors are presented in this paper. The optimized detectors design is simulated and analyzed with Sentaurus TCAD toolkit. The active area of the detector was studied with the laser transient current techniques (TCT) measurement. The characteristics of detector’s 2D position sensitivity and charge collection was studied with an Alibava DAQ system.

Radiation hardness tests of double-sided 3D strip sensors with passing-through columns
NIM-A, Volume 765, 21 November 2014, Pages 155-160
G.-F. Dalla Betta, C. Betancourt, M. Boscardin, G. Giacomini, K. Jakobs, S. Kühn, B. Lecini, R. Mendicino, R. Mori, U. Parzefall, M. Povoli, M. Thomas, N. Zorzi

Abstract: This paper deals with a radiation hardness study performed on double-sided 3D strip sensors with passing-through columns. Selected results from the characterization of the irradiated sensors with a beta source and a laser setup are reported and compared to pre-irradiation results and to TCAD simulations. The sensor performance in terms of signal efficiency is found to be in good agreement with that of other 3D sensors irradiated at the same fluences and tested under similar experimental conditions.

Low-resistance strip sensors for beam-loss event protection
NIM-A, Volume 765, 21 November 2014, Pages 252-257
M. Ullán, V. Benítez, D. Quirion, M. Zabala, G. Pellegrini, M. Lozano, C. Lacasta, U. Soldevila, C. García, V. Fadeyev, J. Wortman, J. DeFilippis, M. Shumko, A.A Grillo, H.F.-W. Sadrozinski

Abstract: AC-coupled silicon strip sensors can be damaged in case of a beam loss due to the possibility of a large charge accumulation in the bulk, developing very high voltages across the coupling capacitors which can destroy them. Punch-through structures are currently used to avoid this problem helping to evacuate the accumulated charge as large voltages are developing. Nevertheless, previous experiments, performed with laser pulses, have shown that these structures can become ineffective in relatively long strips. The large value of the implant resistance can effectively isolate the “far” end of the strip from the punch-through structure leading to large voltages. We present here our developments to fabricate low-resistance strip sensors to avoid this problem. The deposition of a conducting material in contact with the implants drastically reduces the strip resistance, assuring the effectiveness of the punch-through structures. First devices have been fabricated with this new technology. Initial results with laser tests show the expected reduction in peak voltages on the low resistivity implants. Other aspects of the sensor performance, including the signal formation, are not affected by the new technology.

Investigation of silicon sensors for their use as antiproton annihilation detectors
NIM-A, Volume 765, 21 November 2014, Pages 161-166
N. Pacifico, S. Aghion, O. Ahlén, A.S. Belov, G. Bonomi, P. Bräunig, J. Bremer, R.S. Brusa, G. Burghart, L. Cabaret, M. Caccia, C. Canali, R. Caravita, F. Castelli, G. Cerchiari, S. Cialdi, D. Comparat, G. Consolati, C. Da Vià, J.H. Derking, S. Di Domizio, et al.

Abstract: We present here a new application of silicon sensors aimed at the direct detection of antinucleons annihilations taking place inside the sensor?s volume. Such detectors are interesting particularly for the measurement of antimatter properties and will be used as part of the gravity measurement module in the View the MathML sourceAEg¯IS experiment at the CERN Antiproton Decelerator. One of the goals of the View the MathML sourceAEg¯IS experiment is to measure the gravitational acceleration of antihydrogen with 1% precision. Three different silicon sensor geometries have been tested with an antiproton beam to investigate their properties as annihilation detection devices: strip planar, 3D pixels and monolithic pixel planar. In all cases we were successfully detecting annihilations taking place in the sensor and we were able to make a first characterization of the clusters and tracks.

Radiation hard sensor materials for the CMS Tracker Phase II Upgrade – Charge collection of different bulk polarities Original
M. Printz, on behalf of the CMS Tracker Collaboration
NIM-A, Volume 765, 21 November 2014, Pages 29-34

Abstract: The upgrade of the LHC machine to deliver a significantly higher luminosity of about 5×1034 cm-2s-1 is planned to be operational after 2022. This will simultaneously increase the radiation dose for the inner detector systems, requiring new radiation hard sensor materials for the CMS Tracker. To identify the appropriate materials which are able to withstand the radiation environment in the middle to outer layers of the CMS Tracker during the full lifetime of the high luminosity LHC, a large irradiation and measurement campaign has been conducted. Several test structures and sensors have been designed and manufactured on 18 different combinations of wafer materials, thicknesses and production technologies. The structures have been electrically characterised before and after irradiation with different fluences of neutrons and protons. This paper reports the final results on strip sensor performance considering the comparison of p-in-n technology with n-in-p type. Outcomes from signal and noise measurements before and after annealing depending on the radiation dose are discussed and the final recommendation of the CMS Tracker Collaboration for the strip sensor polarity for the Phase II Upgrade is presented.

Development of n+-in-p large-area silicon microstrip sensors for very high radiation environments – ATLAS12 design and initial results
Y. Unno, S.O. Edwards, S. Pyatt, J.P. Thomas, J.A. Wilson, J. Kierstead, D. Lynn, J.R. Carter, L.B.A. Hommels, D. Robinson, I. Bloch, I.M. Gregor, K. Tackmann, C. Betancourt, K. Jakobs, S. Kuehn, R. Mori, U. Parzefall, L. Wiik-Fucks, A. Clark, D. Ferrere, et al.
NIM-A, Volume 765, 21 November 2014, Pages 80-90

Abstract: We have been developing a novel radiation-tolerant n+-in-p silicon microstrip sensor for very high radiation environments, aiming for application in the high luminosity large hadron collider. The sensors are fabricated in 6 in., p-type, float-zone wafers, where large-area strip sensor designs are laid out together with a number of miniature sensors. Radiation tolerance has been studied with ATLAS07 sensors and with independent structures. The ATLAS07 design was developed into new ATLAS12 designs. The ATLAS12A large-area sensor is made towards an axial strip sensor and the ATLAS12M towards a stereo strip sensor. New features to the ATLAS12 sensors are two dicing lines: standard edge space of 910 µm and slim edge space of 450 µm, a gated punch-through protection structure, and connection of orphan strips in a triangular corner of stereo strips. We report the design of the ATLAS12 layouts and initial measurements of the leakage current after dicing and the resistivity of the wafers.