Performance of new radiation tolerant thin n-in-p Silicon pixel sensors for the CMS experiment at High Luminosity LHC (#1691)
M. E. Dinardo1
1 Università degli Studi di Milano Bicocca, Physics Department "G. Occhialini", Milano, Italy
The High Luminosity upgrade of the CERN-LHC (HL-LHC) demands for a new high-radiation tolerant solid-state pixel sensor capable of surviving fluencies up to a few 1016 particles/cm2 at ~3 cm from the interaction point. To this extent the INFN ATLAS-CMS joint research activity in collaboration with Fondazione Bruno Kessler-FBK, is aiming at the development of thin n-in-p type pixel sensors for the HL-LHC. The R&D covers both planar and single-sided 3D columnar pixel devices made on Si-Si Direct Wafer Bonding technique, which allows for the production of sensors with 100 um and 130 um active thickness for planars, and 130 um for 3Ds, the thinnest ones ever produced so far. First prototypes of hybrid modules bump-bonded to the present CMS readout chip, have been tested on beam. Preliminary results on their performance before and after irradiation will be presented.
Keywords: pixel, HL-LHC
Development in a Novel CMOS Process for Depleted Monolithic Active Pixel Sensors (#4057)
R. Bates1, C. Buttar1, M. Dalla2, J. W. Van Hoorne3, T. Kugathasan3, D. Maneuski1, C. A. Marin Tobon3, L. Musa3, H. Pernegger3, P. Riedler3, C. Riegel3, 4, C. Sbarra2, D. M. Schaefer3, A. Sharma3, 5, E. J. Schioppa3, W. Snoeys3, C. Solans Sanchez3, N. Wermes6, K. Moustakas6, T. Hemperek6, T. Wang6
1 University of Glasgow, SUPA School of Physics and Astronomy, Glasgow, United Kingdom of Great Britain and Northern Ireland
The inner tracking system of the ATLAS detector at the Large Hadron Collider (LHC, CERN, Geneva, Switzerland) will undergo a major upgrade (ITk) for the High-Luminosity LHC phase. Depleted Monolithic Active Pixel Sensor (DMAPS) produced in commercial CMOS technologies are being proposed as an alternative to standard hybrid devices, providing increased granularity, lower material budget and production costs.
Prototype chips were implemented by the ALICE collaboration for studies for the upgrade of the ALICE Inner Tracking System (ITS). They have been manufactured in the TowerJazz 180 nm CMOS imaging technology, which provides a deep pwell allowing full CMOS within the pixel. These chips are now being investigated for application in the more challenging ATLAS ITk environment, where tolerance to radiation levels of 1015neq /cm2 are required for the outer pixel layers.
If the circuit in this process occupies a large fraction of the pixel, the sensitive layer, a 1 kΩcm 25 μm thick epitaxial layer, is not fully depleted, and therefore signal charge is not purely collected by drift but also by diffusion. Reverse substrate bias improves the tolerance to non-ionizing energy loss (NIEL) to well above 1013neq /cm2, but not to the 1015neq /cm2 required by the ATLAS ITk. A process modification developed together with the foundry based on a deep planar junction below the in-pixel readout circuitry, enables full depletion of the epitaxial layer, and does not require circuit design modifications, so that designs can be manufactured in both the standard and the modified process for comparison. Measurements with radioactive sources and test beams illustrate sensors implemented with this process have better timing performance and tolerate 1015neq /cm2. They are complemented by detailed charge collection studies using edge transient current measurements using a pulsed laser illuminating the side edge of the sensor. The attached summary gives an overview.
Keywords: CMOS technology, radiation hardening, monolithic active pixel sensors
Modeling of Radiation Damage Effects at High-Luminosity LHC Expected Fluences: Measurements and Simulations (#1985)
A. Morozzi1, F. Moscatelli2, 1, D. Passeri3, 1, G. M. Bilei1, G. - F. Dalla Betta4, 5, M. Bomben6, S. Mattiazzo7
1 INFN, Section of Perugia, Perugia, Italy
This paper describes a physically grounded TCAD modeling approach for the analysis of the effects of radiation damage on silicon detectors at High Luminosity LHC expected fluences (up to 2.2×10E16 n/cm2).
In order to cope with this previously unexperienced fluences, new classes of silicon detectors are being considered. Aiming at the optimization of their performance in terms of tracking capabilities (i.e. inter-electrode isolation and charge collection efficiency), TCAD tools can be proficiently adopted.
To this purpose, a practical, yet physically grounded, modeling approach of the effects of radiation damage on silicon detectors at these very high fluences need therefore to be further developed and validated.
Within this framework, combined bulk and surface damage effects have been accounted for by means of a limited number of measurable parameters, e.g. interface trap state density and oxide charge. Starting from standard test structure measurements (i.e. MOS capacitors, gated diodes and MOSFETs), the previously mentioned parameters can be extracted and fed as input to the simulation tools.
Different technology and design options / detector geometries can be therefore evaluated, from conventional planar pixelated (strip/pixel) detectors to active-edges or 3D (columnar electrodes) detectors, as well different principle of operation such as charge multiplication in Low Gain Avalanche Detector.
Validation of the adopted scheme has been carried out, both in terms of I-V and C-V analyses of simple test structures as well as in terms of breakdown voltages, interstrip resistance and charge collection efficiency of segmented detectors.
This would support the use of the model as a predictive tool to optimize the effect of e.g. different doses of p-spray implants on strip detector isolation properties, as well as the effects of different electrode geometry/configurations in both planar and 3D pixel detectors on breakdown voltage and charge collection properties.
Keywords: Radiation Damage, TCAD Modeling, Silicon Pixel/Strip Detectors
Study of the radiation damage of SiPMs by neutrons (#3446)
E. Garutti1, R. Klanner1, D. Lomitze1, J. Schwandt1, M. Zvolsky1
1 University of Hamburg, IExp, Hamburg, Germany
Silicon Photo-Multipliers (SiPM) are great tools for photo detection; they are being used in several applications in fundamental and applied science. One major consideration for their use at high-luminosity colliders is the radiation damage induced by hadrons, which leads to a dramatic increase of the dark count rate. Last year our group presented a dedicated study of the effect of radiation on SiPM performance based on a sample of KETEK SiPMs exposed to reactor neutrons up to a fluence of 1012 neq/cm2. The conclusion presented at that time was that breakdown voltage, photon detection efficiency PDE, Gain, and correlated noise probability did not change by more than 7% up to the investigated fluence . At the same conference another group  reported significant changes of these parameters for different SiPMs when exposed to fluences above 1012 neq/cm2. To shade light on this potential discrepancy we have extended our studies to a fluence of 5x1014 neq/cm2. Results for KETEK and Hamamatsu SiPMs will be presented in the talk.
Keywords: Silicon photomultipliers, SiPM, radiation damage
3D Diamond Detectors with Metal Electrodes (#3973)
E. D. Lukosi1, T. Wulz1
1 University of Tennessee, Nuclear Engineering, Knoxville, Tennessee, United States of America
This paper discusses the development of a 3D diamond detector using metal electrodes over laser-induced graphitic channels. In our method, we use deep reactive ion etching to create through-diamond vias that are filled with chromium via electroplating. Tests were conducted using an interdigitated readout. Using 241Am alpha particles, we found that the 3D chromium electrodes are electrically active, exhibiting superior performance over a 2D phantom detector at a ten-times lower applied bias. Further, no polarization is observed over a 24-hour period, indicating that no charge trapping at the 3D electrode-diamond interface takes place. The presented fabrication technique provides an enhancement to current technological techniques, reducing the series resistance to the preamplifier by several orders of magnitude and is scalable for mass production using existing commercial facilities.
Keywords: Diamond Detectors, 3D diamond detectors, Radiation Hard Detectors
Neutron Induced Radiation Damage in BaF2, LYSO and PWO Scintillation Crystals (#3853)
C. Hu1, F. Yang1, L. Zhang1, R. - Y. Zhu1, J. Kapustinsky2, R. Nelson2, Z. Wang2
1 California Institute of Technology, Pasadena, California, United States of America
One crucial issue for applications of scintillation crystals in HEP calorimeters is radiation damage in severe radiation environment, such as at the HL-LHC. While radiation damage induced by ionization dose and protons are well studied, investigation is still on-going to understand radiation damage caused by neutrons. In this paper, we report an investigation on neutron induced radiation damage in BaF2, LYSO and PWO crystals by using the neutrons at the Weapons Neutron Research facility of Los Alamos Neutron Science Center.
Keywords: Scintillation Crystals, Neutron, Radiation damage