21st RD50 Workshop (CERN)

14 Nov 2012, 09:00 → 16 Nov 2012, 13:00 Europe/Zurich

CERN

Michael Moll (CERN)

21st RD50 Workshop on Radiation hard semiconductor devices for very high luminosity colliders

Wednesday 14 November

Radiation Damage in LHC detectors

Convener: Stephen Gibson (CERN)

1 Workshop opening

Speakers: Michael Moll (CERN), Stephen Gibson (CERN)

Slides 121114-RD50-Intro-CERN-Moll.pdf 121114-RD50-Intro-CERN-Moll.pptx

2 Radiation damage effects to the CMS Silicon Tracker

Studies of radiation damage to the sensors of the CMS Pixel and Strip Detectors during LHC running in 2011 and 2012 are presented. Leakage current and depletion voltage are monitored with increasing fluence. Methods for addressing the challenges of these measurements in the context of ongoing detector operations are discussed. These include the derivation of depletion voltage from hit efficiencies, the measurement of silicon temperature and extrapolation of current as a function thereof, and determination of the total fluence from LHC luminosity. The results allow for validation of existing radiation damage models of radiation damage and an improved understanding of the anticipated lifetime of the detectors.

Speaker: Seth Zenz (Princeton University (US))

Slides Zenz-CMSTrackerRadiationDmg-21stRD50Mtg-14Nov12-v2.pdf

3 ATLAS Pixel Detector radiation damage monitoring with the High Voltage delivery system

The ATLAS Pixel Detector radiation damage monitoring system uses leakage currents in pixel modules measured with ATLAS Pixel High Voltage delivery system. We present leakage currents measured in 2011 and 2012 and their dependence on the ATLAS integrated luminosity (~ 24 fb^{-1}). We compare them with the theoretical model prediction. The status of the system is presented as well as the prospects for the further studies.

Speaker: Rui Wang (University of New Mexico (US))

Slides rwang_RD50_Nov142012.pdf rwang_RD50_Nov142012.pptx

4 Charge Trapping in the Simulation of ATLAS Semi-Conductor Tracker

One of the main, macroscopic radiation damage effects in silicon detectors is the charge trapping. It occurs when in the bulk of silicon sensors, exposed to intensive irradiation, defects acting as charge traps are induced. As a consequence, the charge collection efficiency of the detector is strongly affected. The charge-trapping effect has been implemented in the simulation framework of the ATLAS Semi-Conductor Tracker. The talk will present the general scheme used for this, together with some preliminary results regarding the detector response as a function of the fluence received.

Speaker: Marco Filipuzzi (Deutsches Elektronen-Synchrotron (DE))

Slides 12_11_14_RD50_charge_trapping_sct.pdf

5 Radiation damage effects in the LHCb Vertex Locator

The effects of radiation damage in the LHCb Vertex Locator have been studied with a variety of techniques, using both 2011 and 2012 data. An overview of these methods, which include bulk currents, the effective depletion voltage, the cluster finding efficiency and noise scans will be given. This will be followed by a summary of the key results using up to 2.7 inverse femtobarn of LHCb delivered luminosity.

Speaker: Jon Harrison (University of Manchester (GB))

Slides RD50_14thNov_2012.pdf

10:40 Coffee Break

6 CMS Preshower

Speaker: Anna Elliott-Peisert (CERN)

Slides IERDWG_meeting_Nov012.pdf IERDWG_meeting_Nov012.pptx

7 Observation of type-inversion in the innermost tracking layer of the ATLAS Pixel Detector

Due to the increasing radiation dose accumulated by the ATLAS Pixel Detector at the LHC, the effects of radiation damage are now clearly observable. Macroscopic effects are induced from the creation of silicon crystal defects and key parameters such as leakage current and effective depletion voltage are routinely monitored. Measurements of the effective depletion voltage show a general trend of reduction due to the decrease of the effective n-doping concentration until the summer of 2012. More recent measurements exploiting a novel track based method reveal a subsequent rise in the effective depletion voltage, indicating type-inversion has occurred in the innermost layer of the Pixel Detector. The results are quantitatively compared with radiation damage models.

Speakers: Andre Lukas Schorlemmer (CERN / Georg-August-Universitaet Goettingen (DE)), Stephen Gibson (CERN)

Slides 121114RD50_ATLAS_Gibson.pdf

8 Multi-Project Wafer (MPW) Runs of Full Custom Pitch Adapters

Since the fabrication of the full series of pitch adapters for the modules of the End-Cap part of the ATLAS Semiconductor Tracker (SCT), from 2003 to 2005, CNM-Barcelona has made several fabrications a year of pitch adaptors for different users. Our technology for pitch adapters is not a PCB-like technology, but a microelectronics technology with clean room fabrication. This is how we achieve the very high density (fine pitch), 0-defects, bonding quality, and high yield. The drawback of this technology is that the fabrication requires a minimum batch of at least 10 wafers, and it is very common that research institutes need a relatively small number of devices for prototyping experiments, therefore a minimum batch of 10 wafers gives them too many more devices than they really need. For this reason we have decided to launch an MPW program in which many users (designs) can share a single batch to reduce costs (as in the case of most microelectronic foundries in the word). In collaboration with Alibava Systems S.L. we can handle both the full custom design of the individual devices, plus the mounting of the full wafer design, and then the fabrication and individualization of the pieces for the different users. We propose to the RD50 community to make MPW (Multi-Project Wafers) for pitch adapters, as it is usually made for ASICs, where many different users place their individual designs for PAs in a full wafer design to obtain smaller series (20, 50, or 120). We think that this could be a good service to the HEP community and, in particular, to the radiation detectors R&D community.

Speaker: Dr Miguel Ullan Comes (Universidad de Valencia (ES))

Slides RD50_MPW-PAs_MUllan.pdf RD50_MPW-PAs_MUllan.ppt

12:10 Lunch

10 years of RD50

Convener: Gianluigi Casse (University of Liverpool (GB))

9 Silicon: survival of the fittest

By necessity, semiconductor silicon detectors are damaged by radiation during their use. Studies have been made since the beginning, in the fifties and sixties, and are continued until today. Understanding of the radiation effects helps to shape devices that can operate under quite harsh conditions. The extreme purity of industrial silicon allows predictability of performance and presents an advantage over other sensor materials.

Speaker: Erik Heijne (Czech Technical University (CZ))

Slides 012-ErikRD50-RR.pdf

Defect and Material Characterization

Convener: Michael Moll (CERN)

10 Electronic properties of vacancy aggregates in n-type silicon for particle detectors

Vacancy aggregates, formed in silicon exposed to high fluences of hadrons or ions, seem to be the main defects limiting radiation hardness of tracking detectors. Recently, the electronic properties of these defects have been intensively studied using theoretical calculations. However, apart from the case of divacancies, very few experimental results concerning the properties higher order vacancy complexes have been obtained. In this paper, we report the new results obtained by the high-resolution photoinduced transient spectroscopy (HRPITS) indicating the presence of trivacancies (V3) both in neutron-irradiated n-type MCz Si and proton irradiated epitaxial silicon. Based on the Laplace spectral fringes, the activation energies for electron emission from deep acceptors V3(2-/-) and V3(-/0), equal to 0.36 and 0.46 eV, respectively, were determined. The activation energies for electron emission from tetravacancy related deep acceptors V4(2-/-) and V4(-/0), are likely to be 0.39 and 0.55 eV, respectively.

Speaker: Prof. Pawel Kaminski (Institute of Electronic Materials Technology)

Slides Kaminski_aggregates_2012_14_11_2.pdf Kaminski_aggregates_2012_14_11_2.pptx

11 Radiation damage in n-type silicon after electron irradiation with energies between 1.5 MeV and 15 MeV

The study of the radiation damage by electrons of different energies allows investigating separately point and cluster defects: 1 MeV electrons produce only point defects, whereas at 15 MeV cluster defects dominate. For these studies pad diodes fabricated on high resistivity n-type Standard Float Zone (STFZ), Diffusion Oxygenated Float Zone (DOFZ) and thin epitaxial layers grown on Czochralski substrate (EPI) were used. The electrical properties of the diodes have been characterized by capacitance- and current-voltage (CV/IV) measurements. For the characterization of the radiation induced defects the Thermally Stimulated Current (TSC) and Deep Level Transient Spectroscopy (DLTS) methods were used. Isothermal annealing at 80 C and isochronal annealing measurements were performed allowing the study of defect kinetics. From DLTS measurements the formation of point and cluster defects as function of electron energy will be demonstrated via the concentration ratio of the single vacancy related defect VO, the double vacancy V2 and the tri vacancy defect complex V3. By TSC measurements the development of cluster related deep hole traps and a shallow donor has been investigated and detailed annealing studies have been performed. These microscopic findings are compared with the development of the macroscopic diode properties.

Speaker: Roxana Radu (Institute for Experimental Physics, Hamburg University)

Slides RD50-Roxana_Radu.pdf

12 RADIATION DEFECT TRANSFORMATIONS UNDER ANNEALING OF P-TYPE SILICON

Comparative studies of radiation defect annealing in p-type silicon diodes made by different producers have been performed. We have studied as pure silicon so silicon-germanium diodes. Radiation defects have been produced by irradiation with electrons and alpha-particles at different temperatures. It has been found that under annealing at temperatures >250 C the concentration of interstitial carbon-interstitial oxygen complex grows up to 50 % in diodes with the highest resistivity. Germanium doping influences annealing behavior of vacancy-type defects but not interstitial-type defects. Direct current injection essentially lowers annealing temperature not only for primary defects but for other secondary interstitial defects and some of their complexes also. Tentative explanations of these observations are presented.

Speaker: Dr Leonid Makarenko (Belarusian state University)

Slides talk_makarenko_geneva2012.pdf

13 Evolution of pulsed current and of carrier lifetime characteristics in Si structures during 25 MeV neutrons irradiation using a spallator type source

Evolution of pulsed current and of carrier lifetime characteristics in Si structures during 25 MeV neutrons irradiation using a spallator type source E.Gaubas1, T.Ceponis1, A.Jasiunas1, A.Uleckas1, J.Vaitkus1, E.Cortina2, and O.Militaru3 1 - Vilnius University, Institute of Applied Research, Vilnius 2 - Center for Cosmology, Particle Physics and Phenomenology, Universite catholique de Louvain 3 - Cyclotron Research Center, Universite catholique de Louvain, Louvain la Neuve Evolution of pulsed current and of carrier lifetime characteristics in Si structures measured in situ during neutron irradiation will be discussed. A spallator type source producing neutrons with energy peak at 25 MeV was exploited in these experiments to perform the on-line measurements at room temperature by combining several techniques operating in distant measurement mode. The obtained changes of pulsed currents and of carrier lifetime characteristics well correlate mutually when considered relatively to an increasing neutron fluence value. Thereby, it has been approved that measurements of correlated lifetime changes, performed in contactless and distant manner and calibrated with other parameters, can be a powerful tool for rather precise prediction of detector performance in a wide dynamic range.

Speaker: Dr Eugenijus Gaubas (Vilnius University)

Slides Geneva-2012--egaubas-In_situ.pdf Geneva-2012--egaubas-In_situ.ppt

14 The free carrier transport properties in proton and neutron irradiated Si(Ge)

The Hall and magnetoresistance were investigated in Si(Ge) initial crystals and irradiated to 1e12 and 1e13 protons and neutrons, and by 4-6 MeV electrons to 3.6e16 cm-2 at different temperature.

Speaker: Prof. Juozas Vaitkus (Vilnius University)

Slides Vaitkus-CERN-RD-2012.pdf Vaitkus-CERN-RD-2012.ppt

15:40 Coffee

15 Charge carrier detrapping in irradiated silicon sensors after microsecond laser pulses

An update on the detrapping time constants for charge carriers in irradiated silicon sensors using the TCT method with long (microsecond) laser pulses is given.

Speaker: Markus Gabrysch (CERN)

Slides MGabrysch_TCT-Detrapping.pdf MGabrysch_TCT-Detrapping.pptx

16 Measurements on 800 MeV proton irradiated diodes (moved to Thursday morning!)

The radiation damage inflicted by protons of different energies leads to differences in the electrical properties of silicon sensors even at similar equivalent fluences. This work aims to understand the impact of radiation damage of protons of different energies. \\ Irradiations in the blue room of the LANSCE facility in Los Alamos with 800 MeV protons have been carried out on a set of Flaot Zone, Magnetic Czochralski and epitaxially grown Diodes. These materials had been under investigation within the RD50 collaboration before, and results of irradiations with 23 GeV protons from PS at CERN and 1 MeV neutrons in Ljubljana are available for comparison.\\ Within this year Brown University has build up a silicon laboratory for electrical sensor characterization. The recently build capacitance-voltage / current-voltage (CV/IV) setup has been used to characterize the proton irradiated samples. Results of the ongoing measurements are presented.

Speaker: Alexandra Junkes (Brown University)

17 MOS Capacitor Displacement Damage Dose (DDD) Dosimeter

On the characterization by experiments and simulation of the possibilities of nanometric MOS capacitors for DDD dosimetry.

Speaker: Dr Fco.Rogelio Palomo Pinto (University of Sevilla, School of Engineering)

Slides RD50Presentación.pdf RD50Presentación.pptx

18 New proton irradiation facility in Ankara

Speaker: Bilge Demirkoz (Middle East Technical University (TR))

Slides rd50.pdf

19 Discussion Session: Materials and Defects

Speaker: Michael Moll (CERN)

Slides 121114-RD50-Discussion-on-defects.pdf 121114-RD50-Discussion-on-defects.pptx

Collaboration Board

Convener: Gregor Kramberger (Jozef Stefan Institute (SI))

slides

• CandidaturaRD50.pdf
• CandidaturaRD50.pptx
• DESY-application.pdf
• LPNHE-application.pdf
• LPNHE-Presentation.pdf
• RD50_Collaboration_board_meeting.pdf
• RD50_Collaboration_board_meeting.pptx

Thursday 15 November

Detector Characterization and Simulations

Conveners: Eckhart Fretwurst (II. Institut fuer Experimentalphysik), Vladimir Eremin (Ioffe Physical Technical Institute of Russian Academy of Scienc)

slides 121115-Friday-Session.pdf 121115-Friday-Session.pptx

20 Irradiation study on diodes of different silicon materials for the CMS tracker upgrade

The aim of the CMS tracker upgrade campaign is to find a new radiation hard sensor material for the HL-LHC upgrade of the CMS tracker. Different test structures and sensors were implemented on a variety of silicon materials with different thicknesses by Hamatsu Photonics, Japan. Samples have been irradiated to fluences up to 1.5E15 with protons at Karlsruhe and the CERN PS and with reactor neutrons at Ljubljana. To find a radiation hard sensor material we investigated current characteristics (I-V), capacitance characteristics (C-V) and characteristics of charge collection (TCT). This talk will present the results concerning dark current, effective doping concentration and charge collection efficiency and their annealing, key parameters in defining a material well suited for the upgrade of the CMS tracker.

Speaker: Joachim Erfle (Hamburg University (DE))

Slides erfle_rd50_2.pdf

21 Impact of proton irradiations on the electrical properties of n-type Si-diodes

Silicon n-type diodes made of FZ and MCz material were manufactured for the CMS HPK campaign and irradiated with 23 MeV and 23GeV protons. At a fluence of 3e14/cm² neq the MCz n-type diodes demonstrate clear type inversion after 23MeV proton irradiation. This does not appear after the irradiation with 23 GeV protons. An influence of process induced bulk defects could be excluded. In order to get a deeper understanding of the differences of the radiation induced defects, the Thermally Stimulated Current Technique (TSC) was used. The sensors were electrically characterized by means of capacitance-voltage (C-V) and current-voltage (I-V) measurements. Transient current technique pulses (TCT) and charge collection efficiency (CCE) measurements have indicated a dependence of the bulk damage on the proton energy. Moreover a dependence on the oxygen concentration of the sensors could be observed.

Speaker: Ms Coralie Neubüser (Úniversity of Hamburg)

Slides RD50.pdf

22 Measurements on 800 MeV proton irradiated diodes (moved from Wednesday!)

Speaker: Alexandra Junkes (Brown University)

Slides junkes_final.pdf

23 First investigation of silicon microstrips for the CMS tracker upgrade using edge-TCT

First measurements of small strip detectors built within the HPK campaign of CMS and characterized using an edge-Transient Current Technique (eTCT) are presented. P and N bulk FZ 320 mum thick detectors are studied and compared to reference Micron detectors. A method to estimate the electric field profile inside the detector using normal incidence TCT and edge-TCT is also presented.

Speaker: Marcos Fernandez Garcia (Universidad de Cantabria (ES))

Slides MarcosFernandez_eTCT_RD50_Nov2012.pdf

24 Temperature dependence of the bulk current in Si

Experimental results on the temperature dependence of the current generated in Si bulk are presented and compared with expectations.

Speaker: Alexandre Chilingarov (Lancaster University (GB))

Slides AChRD50CERN2012_I(T).pdf AChRD50CERN2012_I(T).ppt

25 Charge collection studies on heavily irradiated diodes from the RD50 multiplication run (an update)

Special diodes were designed on RD50 multiplication mask which combine the ease of use of a pad-detector with electric field of a strip detector. A series of charge collection measurements was performed with diodes of different implant properties and thicknesses. The diodes were irradiated with neutrons to the total accumulated fluence of 8e16 cm-2. Charge collection efficiency for 90Sr was measured at each fluence and for selected detectors also during long term annealing. The values were compared between the wafers with different properties as well as with standard pad detectors.

Speaker: Gregor Kramberger (Jozef Stefan Institute (SI))

Slides SpaghtiDiodes.pdf SpaghtiDiodes.pptx

10:40 Coffee Break

26 Annealing of Heavy Irradiated n-on-p Diodes at Temperatures 20°, 40°, 60° and 80°C

N-on-p Micron diodes were irradiated with reactor neutrons to 1x1015, 2x10^15 and 1x10^16 neq/cm^2. Diodes were submitted to graduated annealing steps at 20°, 40°, 60° and 80°C to verify previously accepted accelerating annealing factors. The evolution of leakage currents and full depletion voltage (FDV) were measured. The FDV was determined from Capacity-Voltage curves and Charge Collection –Voltage curves from infrared laser beam.

Speaker: Marcela Mikestikova (Acad. of Sciences of the Czech Rep. (CZ))

Slides mikestikova_rd21.pdf

27 TCT measurements with irradiated strip detectors

TCT measurements with strip detectors will be presented. Focused IR laser light pulses were directed to the surface (top) of the detector and TCT signals were measured at different locations of light impact. Measurements were made with specially designed mini strip detectors in which n-type implants are not fully covered with metal allowing laser TCT measurements also with pulses directed on the implants. Measurements were made with detectors irradiated with neutrons up to 5e15 n/cm2 and were repeated after several annealing steps at 60C.

Speaker: Igor Mandic (Jozef Stefan Institute (SI))

Slides Mandic_RD50_Cern_2012.pdf Mandic_RD50_Cern_2012.pptx

28 Electrical characterisation of heavily irradiated microstrip sensors

Electrical characterisation is made of the n-in-p microstrip sensors irradiated by 1 MeV neutron equivalent fluence up to 1E+16 n/cm2. It is shown that the interstrip capacitance is not affected by irradiation and the interstrip resistance remains very high up to the maximum investigated fluence.

Speaker: Dr Alexandre Chilingarov (Lancaster University, UK)

Slides AChRD50CERN2012_MCMD.pdf AChRD50CERN2012_MCMD.ppt

29 Simulation of irradiated silicon p-bulk sensors

TCAD simulations of irradiated silicon p-bulk sensors have been carried out and the results have been compared to CERN 24 GeV-p irradiated n-in-p diodes. The simulations' results are in good agreement with measured data and allow for realiable predictions on future detectors.

Speaker: Marco Bomben (Univ. P. et Marie Curie (Paris VI) (FR))

Slides n-in-p-irrad-simulation.pdf

30 Simulation of electric field profile in Si irradiated detectors with a consideration of carrier generation parameters

Impact of the parameters which define bulk generation current of Si irradiated detectors on the detector characteristics is analyzed. The electric field profile and space charge/free carrier concentrations are simulated regarding generation current and carrier generation lifetime.

Speaker: Dr Elena Verbitskaya (Ioffe Physical-Technical Institute of Russian Academy of Sciences)

Slides Verbitskaya_21_RD50.pdf Verbitskaya_21_RD50.ppt

12:50 Lunch

31 Simulation of an effective 2-trap radiation damage model

Simulations with an effective 2-trap radiation damage model have been performed. Adjustments of the EVL model and necessity of the adjustments are presented. In particular, the focus is on generated current after irradiation, depletion voltage and TCT simulation. Simulations are compared to IV, CV and TCT measurements done in the framework of the CMS HPK campaign.

Speaker: Robert Eber (IEKP - KIT)

Slides EberRobert_2012_Nov_Simulation.pdf

32 Double Electric field Peak Simulation of Irradiated Detectors Using TCAD tools

This work describes the simulation results performed within the RD50 simulation Group on the Double Electric Field Peak behaviour after radiation damage. As per the decision taken in the last RD50 meeting within the Simulation Group, the radiation damage is simulated by incorporating simple two deep level models in Silvaco and results are compared with modeled data. Since bulk generation current model is not available in the simulator so model parameters are modified, like the capture cross sections, introduction rates and carrier life time. For simplicity we have considered plane parallel silicon detectors, which allows to avoid any hardly predictable effects of the current and field focusing. Double peak structure start becoming visible for higher fluences under certain conditions and results imply that it is possible to implement the EVL model in TCAD simply by parametrization of the material parameters in simulation.

Speaker: Ashutosh Bhardwaj (University of Delhi (IN))

Slides Sim_AB_RD50_Nov_2012.pdf

33 Simulation of Double Junction using Synopsys TCAD

The Synopsys TCAD software package was used to perform a simulation of a simple p+-n-n+ diode containing two defects. The simulation parameters as described in the RD50 Simulation Working Group (V.Eremin) were used and the results of the simulation are compared to the data provided by V.Eremin.

Speaker: Michael Moll (CERN)

Slides 121115-RD50-Simulations-CERN-Moll.pptx

34 Discussion on Detector Characterization and Simulations

Speakers: Eckhart Fretwurst (II. Institut fuer Experimentalphysik), Vladimir Eremin (Ioffe Physical Technical Institute of Russian Academy of Scienc)

Slides DefectsIoana.pdf

Full Detector Systems

Convener: Gregor Kramberger (Jozef Stefan Institute (SI))

15:30 Coffee Break

35 A Portable Telescope Based on the Alibava System for Test Beam Studies

A test beam telescope has been built using the ALIBAVA system to drive its data acquisition. The basic telescope planes consist in four XYT stations. Each station is built from a detector board with two 80-micron-pitch sensors, mounted one in each side and their strips crossing at 90 degrees. The ensemble is coupled to an ALIBAVA daughter board. These stations act as reference frame and allow a precise track reconstruction. The system is triggered by the coincidence signal of the two scintillators located up and down stream. The telescope can hold several devices under tests. Those may be mounted on detector boards coupled to the ALIBAVA daughter board. Each ALIBAVA daughter board (either linked to XYT station or a device under test) is subsequently read by its corresponding mother board. The acquisition system can hold up to 16 mother boards. The whole system is controlled by a master board that synchronizes all the mother boards and collects all the data. The off-line analysis software has been developed to study the charge collection, cluster width, tracking efficiency, resolution, etc, of the devices under test. Moreover, the built-in ALIBAVA TDC allows the analysis of the time profile of the device signal. The ALIBAVA Telescope has been successfully operated in two test runs at the DESY and CERN-SPS beam lines. The complete telescope system will be described and the preliminary results will be presented.

Speaker: Manuel Lozano Fantoba (Universidad de Valencia (ES))

Slides RD50_Nov_2012.v2.pdf RD50_Nov_2012.v2.ppt

36 Update on thin sensors results (will be shown on Friday afternoon in PPS meeting)

Update on Si sensors from 100 micron.

Speaker: Dr Gianluigi Casse (Uniof Liverpool)

Slides Casse-21st.pdf Casse-21st.pptx

37 Charge Collection measurements of n-in-p strip detectors after mixed irradiation to HL-LHC fluences and annealing

Planar n-in-p strip sensors produced by Hamamatsu Photonics were irradiated in consecutive irradiation steps with pions of 280 Mev/c, protons of 25 MeV/c and reactor neutrons resulting in a combined fluence of up to 2.8x1015 neq/cm2. The 320 mum thick devices with p-stop interstrip isolation structures are investigated using electrons from a Sr90 source based on the ALIBAVA readout system. After each irradiation step both charge collection and noise measurements have been conducted. After irradiation to the highest dose consecutive annealing steps were at 60°C performed and again measurements with the beta source setup carried out.

Speaker: Susanne Kuehn (Albert-Ludwigs-Universitaet Freiburg (DE))

Slides Freiburg-SusanneKuehn_RD50_Nov12.pdf

38 Bias effects in highly irradiated n+-p silicon microstrip detectors after long term annealing

Effects of long term applied bias on charge collection properties in highly irradiated and annealed FZ n+-p silicon microstrip detectors were examined using the Alibava read-out system and Edge-TCT. A significant drop of both collected charge and the leakage current is observed after keeping the detectors under bias for longer periods of time (>1000 min). The time pattern is found to be fully repeatable under any bias or temperature and obviously seem to influence charge multiplication only. Applying sufficient bias voltage however (>1000 V), results in high enough SNR even after this fall to the stable level (after ca. 2000 min). Both CCE and the leakage current recover after keeping the detectors at room temperature and no bias for more than 24h.

Speaker: Marko Milovanovic (Jozef Stefan Institute, Ljubljana)

Slides 21st-RD50-Marko-Milovanovic-(IJS).pdf 21st-RD50-Marko-Milovanovic-(IJS).ppt

39 A Charge Collection Study with Dedicated RD50 Charge Multiplication Sensors

We investigate the charge collection efficiency of specially designed charge multiplication silicon strip detectors produced by MICRON in Liverpool under the framework of the CERN RD50 collaboration. Sensors are tested before and after proton and neutron irradiation to fluences of 1e15 and 5e15 neq/cm^2. Charge multiplication structures on these devices include varying diffusion times and energies for the implantation process, different sensor thicknesses, and several different strip width and pitch geometries. The charge collection for the charge multiplication devices is compared to standard silicon strip sensors with no charge multiplication properties. Bulk and interstrip capacitance-voltage and current voltage measurements are also carried out.

Speaker: Christopher Betancourt (Freiburg University)

Slides Betancourt_RD50_Nov12.pdf Betancourt_RD50_Nov12.ppt

40 Investigation of Charge Multiplication in Silicon Strip Sensors

Dedicated sensors provided by RD50 were irradiated with neutrons or protons to 1e15neq/cm2 and 5e15neq/cm2. Charge collection, Signal to noise and leakage current of sensors with different pitch to width ratios have been measured as a function of annealing time and will be shown.

Speaker: Robert Eber (KIT - Karlsruhe Institute of Technology (DE))

Slides RobertEber_rd50_CMUpdate.pdf

41 Status of the RD50 funding request for "detectors with enhanced multiplication"

This project aims to fabricate p-type pixel detectors with a small gain, already shown in their pre-irradiated responses. It can be hoped that the gain implemented in the non-irradiated devices could retain some effect also after irradiation, with a higher multiplication factor with respect to standard structures. In addition, a moderate multiplication value will allow the fabrication of thinner devices with the same output signal. The signal gain should be limited to avoid crosstalk, and to prevent the signal from exceeding the dynamic range of readout electronics.

Speaker: Giulio Pellegrini (Centro Nacional de Microelectrónica (IMB-CNM_CSIC))

Slides

• http://dl.dropbox.com/u/33744765/RD50_Pellegrini.ppt
• RD50_Pellegrini.pdf
• RD50_Pellegrini.ppt

42 Punch through protection of heavily irradiated ATLAS07 mini-sensors.

Protection of AC coupling capacitors from beam splashes has been studied on the heavy irradiated HPK ATLAS07 mini-sensors with special structures, BZ4A,B,C and D, for p-stop ion concentrations 2e12, 4e12 and 1e13 ion/cm^2. Punch through voltage is rapidly increasing with neutron fluence from 4e14 neq/cm^2 to 2e15neq/cm^2 for all tested ion concentrations and for 1E13 ion/cm^2 it is significantly higher than 50V. Measurement prefers PT structure BZ4A and ion concentration ~4E12 ion/cm^2.

Speaker: Dr Jan Bohm (Inst.of Physics AS CR)

Slides Punch_through_protection_of_heavily_irradiated_ATLAS07-CERN-2012-last.pdf Punch_through_protection_of_heavily_irradiated_ATLAS07-CERN-2012-last.pptx

43 Discussion on Full Detector Systems

Speaker: Gregor Kramberger (Jozef Stefan Institute (SI))

Slides Discussion.pdf Discussion.pptx

Workshop Dinner

Friday 16 November

Irradiation Facilities, 3D and Pixel Detectors (joined with ATLAS PPS)

Conveners: Daniel Muenstermann (CERN), Giulio Pellegrini (Universidad de Valencia (ES))

44 Non uniform irradaition of CNM 3D sensors for AFP

Pixel detectors with cylindrical electrodes that penetrate the silicon substrate (so called 3D detectors) offer advantages over standard planar sensors in terms of radiation hardness. In the framework of the ATLAS Forward Physics (AFP) program, work has been carried out to study the suitability of 3D pixel devices for forward proton tracking. Minimal dead area and high efficiency after inhomogeneous irradiation are critical requirements the AFP. Recent results of the characterization of slim-edged devices and beam test studies of in-homogeneously irradiated pixel devices carried out by the 3D R&D and AFP ATLAS groups will be presented.

Speaker: Andrea Micelli (IFAE Barcelona)

Slides AM_RD50_nov2012.pdf

45 Scribe-Cleave-Passivate (SCP) Slim Edge Technology for Silicon Sensors

Within the framework of RD50 and ATLAS PPS collaborations, we are pursuing scribe-cleave-passivate (SCP) technology of making “slim edge” sensors. Such sensors have only a minimal amount of inactive peripheral region, which benefits construction of large-area tracker and imaging systems. Key application steps of this method are surface scribing, cleaving, and passivation of the resulting sidewall. We are working on developing both the technology and understanding of the processed devices performance. Our recent advances with regard to the processing steps and device performance will be described. We will also report on the status of devices processed at the request of the RD50 collaborators.

Speaker: Vitaliy Fadeyev (University of California,Santa Cruz (US))

Slides AUW-RD50_CERN_Nov2012_v2.pdf

46 Progress on the Low Resistance Strip Sensors and Slim Edges Combined RD50 Experiment

An update will be presented on the Common RD50 Project "Low Resistance Strip Sensors". Three RD50 institutes are collaborating in this project (CNM-Barcelona, IFIC-Valencia, and SCIPP-Santa Cruz), in which a new method to enhance the sensor hardness to beam-loss damage is studied. The fabrication has been combined with new experiments related with another RD50 Common Project involving Slim Edges. Wafers for the Low Resistance Strip Sensors experiment have been fabricated, first technological measurements results will be shown.

Speaker: Victor Hugo Benitez Casma (Universidad de Valencia (ES))

Slides 21th_RD50_LowRstrips_VBenitez.pdf

47 Characterization of thin high irradiated n-in-p planar pixel sensor

Silicon pixel modules employing n-in-p planar sensors with an active thickness ranging from 75µm to 285µm were assembled with both FE-I3 and FE-I4 ATLAS chips. The thinned sensors are designed to avoid the signal degradation and ensure the radiation hardness even after high fluences, moreover the n-in-p technology requires a single side processing and is a cost-effective alternative to n-in-n sensors for larger radii of the silicon pixel tracker. In this talk we present and compare results of the characterization of these pixel modules after high irradiation up to a fluence of 1e16 n_eq cm^-2. High precision beam test measurements have been performed with high energy pions at the SpS CERN and compared to results from laboratory obtained using a radioactive Sr90 source. Cluster proprieties, charge collection and tracking efficiency of the devices have been investigated.

Speaker: Stefano Terzo (Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut) (D)

Slides 2012_nov_RD50_CERN.pdf

48 Characterization of active edge planar pixels produced at VTT

We will report about the characterization of FE-I3 and FE-I4 active edge planar n-in-p pixels produced at VTT, Finland. The sensor thickness is 100 um and different geometries of the sensor edges have been implemented, down to an inactive width of only 50 um. The interconnection of the sensors to the ATLAS FE-I3 and FE-I4 chips has been performed at VTT, with solder bump bonding. In addition to the IV characterization, the results of the measurements with a 90Sr source will be discussed. The charge collection properties of the edge pixels will be compared with those in the center region. The first analysis of beam test data obtained with these devices before irradiation at CERN-SPS, using the EUDET telescope, will be presented.

Speaker: Anna Macchiolo (Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut) (D)

Slides Macchiolo_RD50_PPS_NOV2012.pdf

10:40 Coffee Break

49 First experience with radiation-hard active sensors in 180 nm HV CMOS technology

We explore the concept of using a deep-submicron HV CMOS process to produce a drop-in replacement for traditional radiation-hard silicon sensors. Unlike fully integrated monolithic active pixel sensors (MAPS), such active sensors contain simple circuits, e.g. amplifiers and discriminators, but still require a traditional (pixel or strip) readout chip. This approach yields most of the advantages of MAPS (improved resolution, reduced cost and material budget, etc.), without the complication of full integration on a single chip. After outlining the design of the HV2FEI4 test ASIC, characterization results, experience of standalone operation during CERN PS irradiations and first experience obtained with pixel and strip readout will be shown before discussing future prospects of active sensors.

Speaker: Daniel Muenstermann (CERN)

Slides Muenstermann_HV-CMOS.pdf

50 Study of the behaviours of silicon sensor structures, before and after irradiation

Speaker: Yoshinobu Unno (High Energy Accelerator Research Organization (JP))

Slides StudyStructures.pdf StudyStructures.pptx

51 The Birmingham Irradiation Facility

At the end of 2012 the proton irradiation facility at the CERN PS will shut down for two years. With this in mind a new irradiation facility has been setup at Birmingham University. This uses a newly built high intensity area of a 26MeV proton cyclotron in the medical physics department. The facility can be used to irradiate silicon sensors, optical components and mechanical structures (e.g . carbon fiber sandwiches) for the LHC upgrade program. Irradiations of silicon sensors can be carried out, in a temperature controlled cold box that can be scanned through the beam. The facility is described in detail, along with the first tests carried out with mini (1 by 1 cm2) silicon sensors.

Speaker: Richard French (The University of Sheffield)

Slides RD50_Cycloron_Irradiation_Facility_RF.pdf RD50_Cycloron_Irradiation_Facility_RF.pptx

52 RD50 - New structures discussion session

Speaker: Giulio Pellegrini (Universidad de Valencia (ES))

Slides http://dl.dropbox.com/u/33744765/Discussion_newstructures.txt