Alexander Dierlamm

High-voltage particle detectors in commercial CMOS technologies are a detector family that allows implementation of low-cost, thin and radiation-tolerant detectors with a high time resolution. In the R/D phase of the development, a radiation tolerance of 1015neq/cm2, nearly 100% detection efficiency and a spatial resolution of about 3 μm were demonstrated. Since 2011 the HV detectors have first applications: the technology is presently the main option for the pixel detector of the planned Mu3e experiment at PSI (Switzerland). Several prototype sensors have been designed in a standard 180 nm HV CMOS process and successfully tested. Thanks to its high radiation tolerance, the HV detectors are also seen at CERN as a promising alternative to the standard options for ATLAS upgrade and CLIC. In order to test the concept, within ATLAS upgrade R/D, we are currently exploring an active pixel detector demonstrator HV2FEI4; also implemented in the 180 nm HV process.

An option of increasing the luminosity of the Large Hadron Collider (LHC) at CERN to 1035 cm−2 s−1 has been envisaged to extend the physics reach of the machine. An efficient tracking down to a few centimetres from the interaction point will be required to exploit the physics potential of the upgraded LHC. As a consequence, the semiconductor detectors close to the interaction region will receive severe doses of fast hadron irradiation and the inner tracker detectors will need to survive fast hadron fluences of up to above 1016 cm−2. The CERN-RD50 project “Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders” has been established in 2002 to explore detector materials and technologies that will allow to operate devices up to, or beyond, this limit. The strategies followed by RD50 to enhance the radiation tolerance include the development of new or defect engineered detector materials (SiC, GaN, Czochralski and epitaxial silicon, oxygen enriched Float Zone silicon), the improvement of present detector designs and the understanding of the microscopic defects causing the degradation of the irradiated detectors. The latest advancements within the RD50 collaboration on radiation hard semiconductor detectors will be reviewed and discussed in this work.

The Compact Muon Solenoid (CMS) is one of the experiments at the Large Hadron Collider (LHC) under construction at CERN. Its inner tracking system consist of the world largest Silicon Strip Tracker (SST). In total it implements 24,244 silicon sensors covering an area of 206m2. To construct a large system of this size and ensure its functionality for the full lifetime of 10 years under LHC condition, the CMS collaboration developed an elaborate design and a detailed quality assurance program. This paper describes the strategy and shows first results on sensor qualification.

In current particle physics experiments, silicon strip detectors are widely used as part of the inner tracking layers. A foreseeable large-scale application for such detectors consists of the luminosity upgrade of the Large Hadron Collider (LHC), the super-LHC or sLHC, where silicon detectors with extreme radiation hardness are required. The mission statement of the CERN RD50 Collaboration is the development of radiation-hard semiconductor devices for very high luminosity colliders. As a consequence, the aim of the R&D programme presented in this article is to develop silicon particle detectors able to operate at sLHC conditions. Research has progressed in different areas, such as defect characterisation, defect engineering and full detector systems. Recent results from these areas will be presented. This includes in particular an improved understanding of the macroscopic changes of the effective doping concentration based on identification of the individual microscopic defects, results from irradiation with a mix of different particle types as expected for the sLHC, and the observation of charge multiplication effects in heavily irradiated detectors at very high bias voltages.

Geant4 low energy extensions have been used to simulate the X-ray spectra of industrial X-ray tubes with filters for removing the uncertain low energy part of the spectrum in a controlled way. The results are compared with precisely measured X-ray spectra using a silicon drift detector. Furthermore, this paper shows how the different dose rates in silicon and silicon dioxide layers of an electronic device can be deduced from the simulations.

The permittivity and dielectric loss tangent of high-purity silicon with semi-insulating properties achieved by the irradiation with 23-MeV protons have been measured at frequencies from 1 GHz to 15 GHz. The dielectric losses were separated from the conductor losses on the basis of the total loss tangent measurements versus frequency. The resistivity measurements of the material performed at radio frequencies (RF) by means of the capacitance spectroscopy method have shown the non-uniform resistivity distribution in the direction perpendicular to the surface of the semi-insulating wafer. The excellent agreement between the resistivity measurements results at RF and those obtained by using microwave methods have been achieved. It has been confirmed that high-purity, semi-insulating silicon is practically non-dispersive and possesses extremely low dielectric losses that are constant to within experimental errors in the frequency range from 1 GHz to 350 GHz. In this frequency range, the dielectric loss tangent of semi-insulating silicon is equal to 1.2×10−5.

The scheduled High Luminosity upgrade of the CERN Large Hadron Collider presents new challenges in terms of radiation hardness. As a consequence, campaigns to qualify the radiation hardness of detector sensors and components are undertaken worldwide. The effects of irradiation with beams of different particle species and energy, aiming to assess displacement damage in semiconductor devices, are communicated in terms of the equivalent 1 MeV neutron fluence, using the hardness factor for the conversion. In this work, the hardness factors for protons at three different kinetic energies have been measured by analysing the I–V and C–V characteristics of reverse biased diodes, pre- and post-irradiation. The sensors were irradiated at the MC40 Cyclotron of the University of Birmingham, the cyclotron at the Karlsruhe Institute of Technology, and the IRRAD proton facility at CERN, with the respective measured proton hardness factors being: 2.1± 0.5 for 24 MeV, 2.2 ± 0.4 for 23 MeV, and 0.62± 0.04 for 23 GeV. The hardness factors currently used in these three facilities are in agreement with the presented measurements.

Particle therapy is a well established clinical treatment of tumors. More than one hundred particle therapy centers are in operation world-wide. The advantage of using hadrons like protons or carbon ions as particles for tumor irradiation is the distinct peak in the depth-dependent energy deposition, which can be exploited to accurately deposit doses in the tumor cells. To guarantee this, high accuracy in monitoring and control of the particle beam is of the utmost importance. Before the particle beam enters the patient, it traverses a monitoring system which has to give fast feedback to the beam control system on position and dose rate of the beam while minimally interacting with the beam. The multi-wire chambers mostly used as beam position monitors have their limitations when a fast response time is required (drift time). Future developments such as MRI-guided ion beam therapy pose additional challenges for the beam monitoring system, such as tolerance of magnetic fields and acoustic noise (vibrations). Solid-state detectors promise to overcome these limitations and the higher resolution they offer can create additional benefits. This article presents the evaluation of an HV-CMOS detector for beam monitoring, provides results from feasibility studies in a therapeutic beam, and summarizes the concepts towards the final large-scale assembly and readout system.

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.

Abstract 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.

Abstract Nowadays, cancer treatment with ion beam is well established and studied. This method allows to deposit the maximum dose to the tumor and minimize the damage to healthy tissue, due to the Bragg peak of the ion energy deposition near the end of the particle range. During the treatment, it is possible to provide volumetric dose delivery by changing the particle energy (penetration depth) and adjusting the beam position via a magnetic system. For the beam monitoring system, the precise measurement of the beam direction, shape and fluence in real time becomes crucial to provide effective and safe dose delivery to the tumor. Additionally, the system should work for beam intensities up to 10 10 s -1 for protons, be tolerant to 1 MeV neutron equivalent fluences up to 10 15 cm -2 per year and be to tolerant to magnetic fields (for MR-guided ion beam). The studies presented in this article are focused on the application of the HitPix sensor family with counting electronics and frame-based readout for such a beam monitoring system. The HitPix sensors are monolithic pixelated silicon sensors based on HV-CMOS technology and have been developed at the ASIC and Detector Lab (ADL, KIT). Recent measurements with ion beams and a multi-sensor readout as well as future developments are discussed.

A new generation of semi-conducting pixel sensors for detecting minimum ionising particles (m.i.p.) was designed and first prototypes of Monolithic Active Pixel Sensors (MAPS), called MIMOSA,2 were fabricated in a standard CMOS technology. The performances of the first prototypes were evaluated with high energy π− beams and with an X-ray source in strong magnetic fields. The beam test results demonstrate that the sensors detect m.i.p.s with very high efficiency and signal-to-noise ratio and provide excellent spatial resolution. The influence of strong magnetic fields is observed to be modest.

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.

Abstract SUCIMA (Silicon Ultra fast Cameras for electron and γ sources In Medical Applications) is a project approved by the European Commission with the primary goal of developing a real time dosimeter based on direct detection in a Silicon substrate. The main applications, the detector characteristics and technologies and the data acquisition system are described.

Preparing for the high-luminosity phase of LHC the CMS Tracker collaboration has started a campaign to identify the future planar silicon sensor technology baseline for a new Tracker. A variety of 6 inch wafers have been ordered in different thicknesses and technologies at HPK. Thicknesses ranging from 50μm to 300μm are explored on float-zone, magnetic Czochralski and epitaxial material both in n-in-p and p-in-n versions. p-stop and p-spray are explored as isolation technologies for the n-in-p type sensors as well as the feasibility of double metal routing on 6 inch wafers. To explore the limits of the technologies many different structures have been designed to answer different questions, e.g. geometry, Lorentz angle, radiation tolerance, annealing behavior, read-out schemes. This contribution provides an overview of the individual structures and their characteristics and summarizes measurements done on small strip sensors before and after irradiations.

In the next generation of collider experiments detectors will be challenged by unprecedented particle fluxes. Thus large detector arrays of highly pixelated detectors with minimal dead area will be required at reasonable costs. Bump-bonding of pixel detectors has been shown to be a major cost-driver. KIT is one of five production centers of the CMS barrel pixel detector for the Phase I Upgrade. In this contribution the SnPb bump-bonding process and the production yield is reported. In parallel to the production of the new CMS pixel detector, several alternatives to the expensive photolithography electroplating/electroless metal deposition technologies are developing. Recent progress and challenges faced in the development of bump-bonding technology based on gold-stud bonding by thin (15 μm) gold wire is presented. This technique allows producing metal bumps with diameters down to 30 μm without using photolithography processes, which are typically required to provide suitable under bump metallization. The short setup time for the bumping process makes gold-stud bump-bonding highly attractive (and affordable) for the flip-chipping of single prototype ICs, which is the main limitation of the current photolithography processes.

The LHC is planning an upgrade program, which will bring the luminosity to about 5−7×1034 cm−2 s−1 in 2026, with a goal of an integrated luminosity of 3000 fb−1 by the end of 2037. This High Luminosity LHC scenario, HL-LHC, will require a preparation program of the LHC detectors known as Phase-2 Upgrade. The current CMS Tracker is already running beyond design specifications and will not be able to cope with the HL-LHC radiation conditions. CMS will need a completely new Tracker in order to fully exploit the highly demanding operating conditions and the delivered luminosity. The new Outer Tracker system is designed to provide robust tracking as well as Level-1 trigger capabilities using closely spaced modules composed of silicon macro-pixel and/or strip sensors. Research and development activities are ongoing to explore options and develop module components and designs for the HL-LHC environment. The design choices for the CMS Outer Tracker Upgrade are discussed along with some highlights of the R&D activities.

Strip detectors with an area of 16cm2 were processed on high resistivity n-type magnetic Czochralski silicon. In addition, detectors were processed on high resistivity Float Zone wafers with the same mask set for comparison. The detectors were irradiated to several different fluences up to the fluence of 3×10151MeVneq/cm2 with protons or with mixed protons and neutrons. The detectors were fully characterized with CV- and IV-measurements prior to and after the irradiation. The beam test was carried out at the CERN H2 beam line using a silicon beam telescope that determines the tracks of the incoming particles and hence provides a reference measurement for the detector characterization. The n-type MCz-Si strip detectors have an acceptable S/N at least up to the fluence of 1×1015neq/cm2 and thus, they are a feasible option for the strip detector layers in the SLHC tracking systems.

It is foreseen to significantly increase the luminosity of the Large Hadron Collider (LHC) at CERN around 2018 by upgrading the LHC towards the SLHC (Super-LHC). Due to the radiation damage to the silicon detectors used, the physics experiments will require new tracking detectors for SLHC operation. All-silicon central trackers are being studied in ATLAS, CMS and LHCb, with extremely radiation hard silicon sensors for the innermost layers. The radiation hardness of these new sensors must surpass the one of LHC detectors by roughly one order of magnitude. Within the CERN RD50 collaboration, a massive R&D program is underway to develop silicon sensors with sufficient radiation tolerance. We will report on recent results obtained by RD50 from tests of several detector technologies and silicon materials at radiation levels corresponding to SLHC fluences. Based on these results, we will give recommendations for the silicon detector technologies to be used at the different radii of SLHC tracking systems.

With increasing instantaneous and integrated luminosities of collision experiments the requirements on position sensitive detectors and sensor materials increase rapidly.Numerous R&D projects of several collaborations have investigated known and new materials with respect to their range of application.This report gives an overview of the current activities and common understanding of planar sensors concentrating on operational aspects.

With an expected 10-fold increase in luminosity in S-LHC, the radiation environment in the tracker volumes will be considerably harsher for silicon-based detectors than the already harsh LHC environment. Since 2006, a group of CMS institutes, using a modified CMS DAQ system, has been exploring the use of Magnetic Czochralski silicon as a detector element for the strip tracker layers in S-LHC experiments. Both p+/n-/n+ and n+/p-/p+ sensors have been characterized, irradiated with proton and neutron sources, assembled into modules, and tested in a CERN beamline. There have been three beam studies to date and results from these suggest that both p+/n-/n+ and n+/p-/p+ Magnetic Czochralski silicon are sufficiently radiation hard for the R>25cm regions of S-LHC tracker volumes. The group has also explored the use of forward biasing for heavily irradiated detectors, and although this mode requires sensor temperatures less than −50 °C, the charge collection efficiency appears to be promising.

Future experiments will use silicon sensors in the harsh radiation environment of the LHC (Large Hadron Collider) and high magnetic fields. The drift direction of the charge carriers is affected by the Lorentz force due to the high magnetic field. Also the resulting radiation damage changes the properties of the drift. In this paper measurements of the Lorentz angle of electrons and holes before and after irradiation are reviewed and compared with a simple algorithm to compute the Lorentz angle.

A heavily irradiated (3×1015 1 MeV neq/cm2) Current Injected Detector (CID) was tested with 225 GeV muon beam at CERN H2 beam line. In the CID concept the current is limited by the space charge. The injected carriers will be trapped by the deep levels and this induces a stable electric field through the entire bulk regardless of the irradiation fluence the detector has been exposed to. The steady-state density of the trapped charge is defined by the balance between the trapping and the emission rates of charge carriers (detrapping). Thus, the amount of charge injection needed for the electric field stabilization depends on the temperature. AC-coupled 16 cm2 detector was processed on high resistivity n-type magnetic Czochralski silicon, and it had 768 strips, 50 μm pitch, 10 μm strip width and 3.9 cm strip length. The beam test was carried out using a silicon beam telescope that is based on the CMS detector readout prototype components, APV25 readout chips, and eight strip sensors made by Hamamatsu having 60 μm pitch and intermediate strips. The tested CID detector was bonded to the APV25 readout, and it was operated at temperatures ranging from −40 to −53 °C. The CID detector irradiated at 3×1015 1 MeV neq/cm2 fluence shows about 40% relative Charge Collection Efficiency with respect to the non-irradiated reference plane sensors.

A new pixel detector for the CMS experiment was built in order to cope with the instantaneous luminosities anticipated for the Phase~I Upgrade of the LHC. The new CMS pixel detector provides four-hit tracking with a reduced material budget as well as new cooling and powering schemes. A new front-end readout chip mitigates buffering and bandwidth limitations, and allows operation at low comparator thresholds. In this paper, comprehensive test beam studies are presented, which have been conducted to verify the design and to quantify the performance of the new detector assemblies in terms of tracking efficiency and spatial resolution. Under optimal conditions, the tracking efficiency is $99.95\pm0.05\,\%$, while the intrinsic spatial resolutions are $4.80\pm0.25\,\mu \mathrm{m}$ and $7.99\pm0.21\,\mu \mathrm{m}$ along the $100\,\mu \mathrm{m}$ and $150\,\mu \mathrm{m}$ pixel pitch, respectively. The findings are compared to a detailed Monte Carlo simulation of the pixel detector and good agreement is found.

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 (LN2) 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 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.

The LHC accelerator complex will undergo a programme of consolidation and upgrade of various components, with the goal of exceeding a peak luminosity of 1034cm-2s-1 (original design figure) around the year 2012; to eventually reach values close to 1035cm-2s-1. The increase in luminosity poses new challenges to the detector operation, both in terms of instantaneous and integrated particle rates. In CMS, the systems that have been identified as requiring substantial upgrades are the Tracker and the Level 1 trigger. The tracking system needs higher readout granularity and higher radiation tolerance, at the same time with reduced power dissipation and a smaller material budget, which are already limiting the performance of the present detector. The trigger system needs to include tracking information at Level 1, to maintain an acceptable rate without losing efficiency for physics channels. These requirements further complicate the design of a new Tracker detector and its readout architecture. This report describes the current status of our CMS Tracker upgrade activities.

Radiation hardness up to 1016 neq/cm2 is required in the future HEP experiments for most inner detectors. However, 1016 neq/cm2 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 (1016 neq/cm2). 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 LN2 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 LN2 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.

The CERN RD39 Collaboration is developing super-radiation hard cryogenic Si detectors for applications in experiments of the LHC and the future LHC Upgrade. Radiation hardness up to the fluence of 1016 neq/cm2 is required in the future experiments. Significant improvement in the radiation hardness of silicon sensors has taken place during the past years. However, 1016 neq/cm2 is well beyond the radiation tolerance of even the most advanced semiconductor detectors made by commonly adopted technologies. Furthermore, at this radiation load the carrier trapping will limit the charge collection depth to the range of 20–30 μm regardless of the depletion depth. The key of our approach is freezing the trapping that affects Charge Collection Efficiency (CCE).

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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">16</sup> 1 MeV neutron equivalent/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

Front-side biasing is an alternative method to bias a silicon sensor. Instead of directly applying high voltage to the backside, one can exploit the conductive properties of the edge region to bias a detector exclusively via front-side connections. This option can be beneficial for the detector design and might help to facilitate the assembly process of modules. The effective bias voltage is affected by the resistance of the edge region and the sensor current. The measurements of n-in-p sensors performed to qualify this concept have shown that the voltage drop emerging from this resistance is negligible before irradiation. After irradiation, however, the resistivity of the edge region increases with fluence and saturates in the region of 107 Ω cm at fluences above 6 ⋅ 1014 neqcm−2 and an operation temperature of −20 oC. The measurements are complemented by TCAD simulations and interpretations of the observed effects.

In this paper we study the Lorentz angles of both electrons and holes in magnetic fields up to 8T and temperatures between 77 and 300K. This is done before and after irradiating a detector with 21 MeV protons up to a fluence of 1013/cm2, which is equivalent to ≈2.8×1013/cm2 1 MeV neutrons.

Abstract The tracking system of the CMS experiment at the LHC collider (CERN) is based on silicon micro-strip detectors. They will be exposed to an equivalent fluence of up to 1.6×10 14 n (1 MeV )/ cm 2 during 10 years of operation. The survival of the sensors in such a radiation environment depends strongly on the sensor design and on the choice of appropriate material. During production we have to verify not only the current quality of the delivered sensors (optical and electronic inspection) but also their radiation hardness. After irradiation to the exposed fluence plus a safety factor, the quality of bulk and surface parameters is verified. Required protocol, measurements and results are presented.

Real time dosimetry is a critical issue in most radiotherapy applications. SUCIMA (Silicon Ultra fast Cameras for electron and gamma sources In Medical Applications) is a project addressing the development of an imaging technique of extended radioactive sources based on monolithic and hybrid position sensitive silicon sensors, where "imaging" has to be understood as the record of a dose map. The requirements for the detectors are given by the main applications, namely brachytherapy and real time monitoring of a proton beam for oncology. The key issues in the sensor and DAQ development are described together with the most relevant medical applications. SUCIMA is a project supported by the European Commission.

RD39 collaboration develops new detector techniques for particle trackers, which have to withstand fluences up to 1016cm−2 of high-energy particles. The work focuses on the optimization of silicon detectors and their readout electronics while keeping the temperature as a free parameter. Our results so far suggest that the best operating temperature is around 130K. We shall also describe in this paper how the current-injected mode of operation reduces the polarization of the bulk silicon at low temperatures, and how the engineering and materials problems related with vacuum and low temperature can be solved.

P-on-n silicon strip sensors having multiple guard-ring structures have been developed for High Energy Physics applications. The study constitutes the optimization of the sensor design, and fabrication of AC-coupled, poly-silicon biased sensors of strip width of 30μm and strip pitch of 55μm. The silicon wafers used for the fabrication are of 4 inch n-type, having an average resistivity of 2–5 kΩ cm, with a thickness of 300μm. The electrical characterization of these detectors comprises of: (a) global measurements of total leakage current, and backplane capacitance; (b) strip and voltage scans of strip leakage current, poly-silicon resistance, interstrip capacitance, interstrip resistance, coupling capacitance, and dielectric current; and (c) charge collection measurements using ALiBaVa setup. The results of the same are reported here.

In this work we address the effects of bulk and surface damages on detectors fabricated by Hamamatsu on standard float zone (FZ) p-type material with an active thickness of 290 µm or thinned to 240 µm. In order to disentangle the effects of the two main radiation damage mechanisms, ionization effects and atomic displacement, the structures underwent two types of radiation: X-ray with doses from 0.05 to 70 Mrad (SiO2) and neutron in the range of 1−10 × 1014 neq/cm21MeV equivalent. The combined surface and bulk damage could be investigated in structures that underwent both types of irradiation. A wide set of measurements has been carried out on the test structures for a complete characterization.

The High-Luminosity LHC upgrade (HL-LHC) is expected to increase the present luminosity by an order of magnitude in the years after 2022. This will necessitate the construction of silicon tracking detectors with a significantly higher radiation hardness and a higher channel granularity to cope with the higher track occupancy. In addition, a contribution from the tracking system to the first trigger stage and a reduction of the material budget would be desirable. The current concept for an upgraded CMS Tracker is based on silicon sensor modules formed of a sandwich of two strip sensors with front-end electronics at the sensor edge. This arrangement allows us to use the displacement of coincident hits in the two stacked sensor planes as a measure of particle momentum. As a consequence it is possible to identify locally particles with low transverse momentum which are not relevant for the Level-1 trigger decision. By applying a momentum cut of 1–2 GeV, the data rate can be reduced by an order of magnitude. This paper introduces a new strip sensor design with a fourfold segmentation along the strips. The inner strips have an offset of half a pitch with respect to the outer strips and are connected to the pre-amplifiers at the edge via routing lines in between the outer strips. The challenge lies in minimizing the induced signals on the routing lines. Several prototypes have been tested and the results are reported. The possible application for the CMS Tracker upgrade is discussed.

A very robust and redundant tracking system is needed to fully exploit the physics potential at the future International Linear Collider. The International Large Detector uses a combination of a TPC surrounded in the barrel region by three double layers of silicon strip sensors as tracking system. In November 2009 a first test beam, including both a Large TPC Prototype and a first prototype of the silicon layers, was performed at DESY, Hamburg. About 80,000 events were recorded using an electron beam with a momentum of 5.6 GeV/c. The emphasis of this paper is on the silicon layers and their performance during the test beam. It presents first results from the data analysis and discusses possible future steps.

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 130K. 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 300K. These results and the ones obtained from non-irradiated detectors are compared with simulations.

Abstract 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 is a project approved by the EC within the V Framework Program.

Abstract 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 effort to characterise detector sensors and components for the High Luminosity upgrade of the CERN Large Hadron Collider requires collaboration between irradiation facilities around the world. By convention, the radiation damage following irradiation with particle beams is reported as the 1 MeV neutron equivalent fluence, obtained using the corresponding hardness factor. Measurements of proton hardness factors at three different kinetic energies are presented, by characterisation of commercially available diodes before and after irradiation, using irradiations at the University of Birmingham, the Karlsruhe Institute of Technology, and CERN. Possible future improvements to these measurements are also discussed.

Abstract Silicon strip sensors of upcoming tracking detectors in high luminosity colliders usually consist of a p-doped bulk with n-type strip implants. The general consensus is that such a design requires an additional interstrip isolation structure such as a p-stop implant. If there is no additional implant between the strips, it is expected that the strip isolation will be insufficient. Before irradiation, impurities and defects in the material lead to positive charge in the oxide and Si/SiO_2 interface which attracts electrons from the bulk. Those electrons accumulate just beneath the surface and between the n + strip or pixel implants, which decreases the interstrip resistance significantly. Ionising radiation introduces even more charge inside the silicon dioxide, which further decreases the interstrip resistance. Contrary to that expectation of a decreasing interstrip resistance due to irradiation, a high interstrip resistance was sometimes observed after proton irradiation. Hence, bulk defects induced by proton irradiation seem to have a non-negligible impact on the strip isolation. Therefore, an irradiation campaign with sensors without any interstrip isolation implant has been performed. The use of sensors without isolation structures provides deeper insight into the dominant isolation effects. The sensors' performance is first evaluated before irradiation. Afterwards, a set of sensors is irradiated with different particles in order to systematically introduce a mixture of surface and bulk defects. This enables the distinction and leads to a better understanding of the different effects. Finally, a combined TCAD model is derived which is able to describe the beneficial effect of bulk defects and the complicated interplay between surface and bulk damage.

The CMS experiment at the LHC, CERN, will operate the largest tracker in the world entirely made of silicon detectors. The collaboration is facing the quality assurance work to prove the reliability and performance of the various parts produced by industry. A status report on the CMS Tracker is given, including the validation of single modules up to larger integrated substructures

The CERN RD39 Collaboration studies the possibility to extend the detector lifetime in a hostile radiation environment by operating them at low temperatures. The outstanding illustration is the Lazarus effect, which showed a broad operational temperature range around 130 K for neutron irradiated silicon detectors.

While the tracking detectors of the ATLAS and CMS experiments have shown excellent performance in Run 1 of LHC data taking, and are expected to continue to do so during LHC operation at design luminosity, both experiments will have to exchange their tracking systems when the LHC is upgraded to the high-luminosity LHC (HL-LHC) around the year 2024. The new tracking systems need to operate in an environment in which both the hit densities and the radiation damage will be about an order of magnitude higher than today. In addition, the new trackers need to contribute to the first level trigger in order to maintain a high data-taking efficiency for the interesting processes. Novel detector technologies have to be developed to meet these very challenging goals. The German groups active in the upgrades of the ATLAS and CMS tracking systems have formed a collaborative "Project on Enabling Technologies for Silicon Microstrip Tracking Detectors at the HL-LHC" (PETTL), which was supported by the Helmholtz Alliance "Physics at the Terascale" during the years 2013 and 2014. The aim of the project was to share experience and to work together on key areas of mutual interest during the R&amp;D phase of these upgrades. The project concentrated on five areas, namely exchange of experience, radiation hardness of silicon sensors, low mass system design, automated precision assembly procedures, and irradiations. This report summarizes the main achievements.

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 MIMOSA1-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.

, T. Barvich , F. Hartmann , Th. Muller1 - Institute of High Energy Physics of the Austrian Academy of Sciences (HEPHY)Nikolsdorfergasse 18, 1050 Vienna - Austria2 - Institut fur Experimentelle Kernphysik - Forschungszentrum Karlsruhe (IEKP)Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen - GermanyThe Linear Collider TPC collaboration constructed a Large Prototype TPC (LPTPC)which is now installed at the EUDET facility, in DESY. The SiLC-collaboration (Siliconfor the Linear Collider) will install position sensitive silicon strip sensors outside the eld cage of the LPTPC, to provide precise tracking information. The data acquisitionsystem (DAQ) is an adapted CMS readout system. The silicon modules are testedand ready to be installed, the mechanical module support and the DAQ system are inpreparation.

The Linear Collider TPC collaboration constructed a Large Prototype TPC (LPTPC) which is now installed at the EUDET facility, in DESY. The SiLC-collaboration (Silicon for the Linear Collider) will install position sensitive silicon strip sensors outside the field cage of the LPTPC, to provide precise tracking information. The data acquisition system (DAQ) is an adapted CMS readout system. The silicon modules are tested and ready to be installed, the mechanical module support and the DAQ system are in preparation.

Particle therapy is a well established clinical treatment of tumors. More than one hundred particle therapy centers are in operation world wide. The advantage of using hadrons like protons or carbon ions as particles for tumor irradiation is the distinct peak in the depth dependent energy deposition, which can be exploited to accurately deposit dose in the tumor cells. To guarantee this, high accuracy of monitoring and control of the particle beam is of utmost importance. Before the particle beam enters the patient, it traverses a monitoring system which has to give fast feedback to the beam control system on position and dose rate of the beam while minimally interacting with the beam. The multi-wire chambers mostly used as beam position monitor have their limitations when fast response time is required (drift time). Future developments like MRI-guided ion beam therapy pose additional challenges for the beam monitoring system like tolerance of magnetic fields and acoustic noise (vibrations). Solid-state detectors promise to overcome these limitations and the higher resolution they offer can create additional benefits. This article presents the evaluation of an HV-CMOS detector for beam monitoring, provides results from feasibility studies in a therapeutic beam and summarizes the concepts towards the final large-scale assembly and readout system.

This contribution summarizes an extensive simulation study of three different bias rail approaches for segmented strip and pixel sensors, comparing their charge collection efficiency and the maximum electric field in the bulk. Therefore a combined heavy ion and transient simulation was performed. By moving the interception point of the particle and integrating over the induced current at the pixel contacts and the backside, a spatial dependency of the charge collection efficiency (CCE) was obtained. The results show that a common p-stop configuration, where the bias rail is effectively shielded by the p+ implantation, leads to a constant CCE close to 100% along the sensor and the lowest maximal electric field in the bulk. The results have been utilized in the design process of a new macro-pixel prototype which is shown at the end of this contribution.

With increasing luminosity of accelerators for experiments in high energy physics the demands on the detectors increase as well. Especially tracking and vertexing detectors made of silicon sensors close to the interaction point need to be equipped with more radiation hard devices. This article introduces the different types of silicon sensors, describes measures to increase radiation hardness and provides an overview of the present upgrade choices for experiments in high energy physics.

The silicon sensors to be deployed in the next generation high energy physics experiments for operation in high luminosity scenarios, will require a high level of radiation tolerance. AC-coupled silicon strip sensors integrated with biasing poly-silicon resistors have been fabricated in collaboration with the Bharat Electronics Limited foundry using 4 inch n-type wafers in p-on-n configuration. Several sensors were irradiated with protons at different fluences at the Karlsruhe Cyclotron facility under the Advanced European Infrastructures for Detectors at Accelerators (AIDA) program. This paper reports on these radiation hardness study performed on the AC-coupled silicon sensors fabricated in India. The characterization comprises of electrical tests, including total current, voltage and strip scans and charge collection studies.

Linear array detectors with high spatial resolution and MHz frame-rates are essential for high-rate experiments at accelerator facilities. KALYPSO, a line array detector with 1024 pixels operating over 1 Mfps has been developed. To improve the spatial resolution and sensitivity at different wavelengths, novel p-in-n Si microstrip sensors based on have been developed with a pitch of 25 micrometer. The efficiency of the sensor has been improved with the use of anti reflecting coating layers optimized for near infrared, visible and near ultraviolet. In this contribution the detector system and the sensors will be presented.

KARATE (KArlsruhe high RAte TEst) is a new test system to stress test the readout chain of detector modules for the upgrade of the CMS Outer Tracker for the high-luminosity LHC.Modules consisting of two silicon strip sensors, called 2S modules, are deployed in the outer regions of the Outer Tracker.The readout chain of a 2S module consists of 16 CMS Binary Chips (CBC) each connected to two stacked silicon strip sensors.The CBC contributes data to the first trigger level by identifying particles with large transverse momenta.The output is sparsified on two concentrator chips which in turn are connected to a Gigabit transceiver that prepares the data for output through an optical module.Standard test systems such as test beams or radioactive source measurements need a track reconstruction or do have Gaussian distributed hit profiles and do not reach the occupancy or trigger rates expected in the future Outer Tracker of CMS.KARATE uses a combination of LEDs and photodiodes to inject hit patterns with varying pulse heights, occupancies and trigger rates into the front-end of the CBC, giving full control on 48 channels at 40 MHz.This offers the opportunity to directly compare injection patterns with readout patterns.This contribution introduces the test system and summarizes measurements on a CBC that is read out electrically.

This article explores the viability of nitrogen enriched silicon for particle physics application. For that purpose silicon diodes and strip sensors were produced using high resistivity float zone silicon, diffusion oxygenated float zone silicon, nitrogen enriched float zone silicon and magnetic Czochralski silicon. The article features comparative studies using secondary ion mass spectrometry, electrical characterization, edge transient current technique, source and thermally stimulated current spectroscopy measurements on sensors that were irradiated up to a fluence of 10 15 n eq /cm 2 . Irradiations were performed with 23 MeV protons at the facilities in Karlsruhe (KIT), with 24 GeV/c protons at CERN (PS-IRRAD) and neutrons at the research reactor in Ljubljana. Secondary ion mass spectrometry measurements give evidence for nitrogen loss after processing, which makes gaining from nitrogen enrichment difficult.

The CMS experiment at the LHC, CERN, will operate the largest tracker in the world entirely made of silicon detectors. The collaboration is facing the quality assurance work to prove the reliability and performance of the various parts produced by industry. A status report of the CMS tracker is given, including the validation of single modules up to larger integrated sub-structures.

Abstract The start of the High-Luminosity LHC (HL-LHC) in 2027 requires upgrades to the Compact Muon Solenoid (CMS) experiment. In the scope of the upgrade program the complete silicon tracking detector will be replaced. The new CMS Tracker will be equipped with silicon pixel detectors in the inner layers closest to the interaction point and silicon strip detectors in the outer layers. The new CMS Outer Tracker will consist of two different kinds of detector modules called PS and 2S modules. Each module will be made of two parallel silicon sensors (a macro-pixel sensor and a strip sensor for the PS modules and two strip sensors for the 2S modules). Combining the hit information of both sensor layers, it is possible to estimate the transverse momentum of particles in the magnetic field of 3.8 T at the full bunch-crossing rate of 40 MHz directly on the module. This information will be used as an input for the first trigger stage of CMS. It is necessary to validate the Outer Tracker module functionality before installing the modules in the CMS experiment. Besides laboratory-based tests several 2S module prototypes have been studied at test beam facilities at CERN, DESY and FNAL. This article concentrates on the beam tests at DESY during which the functionality of the module concept was investigated using the full final readout chain for the first time. Additionally the performance of a 2S module assembled with irradiated sensors was studied. By choosing an irradiation fluence expected for 2S modules at the end of HL-LHC operation, it was possible to investigate the particle detection efficiency and study the trigger capabilities of the module at the beginning and end of the runtime of the CMS experiment.

Future detectors will use silicon sensors in the harsh radiation environment of the LHC (Large Hadron Collider) and high magnetic fields.The drift direction of the charge carriers is affected by the Lorentz force due to the high magnetic field.Also the resulting radiation damage changes the properties of the drift.This note describes the measurements of the Lorentz angle and a simple algorithm to calculate it as function of bias voltage, magnetic field and temperature.* Speaker.

CMSsiliconmicrostripdetectors of different types equipped with the APV readoutchips have been exposed to a high intensity 350 MeV/c pion beam. We study theperformance of irradiated and non-irradiated silicon sensors as well as the readoutchip behavior. Maximum signal to noise for the irradiated oxygenated sensor hasreached 15 in deconvolution mode.