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Investigators

Alan Astbury (Victoria) 100 % David Axen (UBC) 100 % Georges Azuelos (Montreal/TRIUMF)´ 75 % David C. Bailey (Toronto) 100 % Sampa Bhadra (York) 10 % G. Couture (Montreal/UQAM)´ 50 % Madhu Dixit (Carleton) 20 % Douglas Gingrich (Alberta/TRIUMF) 50 % Richard Keeler (Victoria) 100 % Peter Krieger (Toronto/IPP) 100 % Michel Lefebvre (Victoria) 100 % Claude Leroy (Montreal)´ 100 % Mike Losty (TRIUMF) 100 % Jean-Pierre Martin (Montreal)´ 30 % John McDonald (Alberta) 30 % Robert McPherson (Victoria/IPP) 100 % Roger W. Moore (Alberta) 25 % Gerald Oakham (Carleton) 100 % Dugan O’Neil (SFU) 25 % Chris Oram (TRIUMF) 100 % Robert S. Orr (Toronto) 90 % James Pinfold (Alberta) 70 % Pekka Sinervo (Toronto) 30 % Randy Sobie (Victoria/IPP) 70 % William Trischuk (Toronto) 20 % Michel C. Vetterli (SFU/TRIUMF) 70 % Manuella Vincter (Alberta) 80 % Trischuk PIN 101982 2

Collaborators

K. Benslama RA (Montreal)´ 100 % Bryan Caron RA (Alberta/TRIUMF) 100 % Sergey Chekulaev RA (TRIUMF) 100 % Margret Fincke-Keeler RA (Victoria) 100 % Petr Gorbunov RA (Toronto) 100 % Mohsen Khahkzad RA (Carleton) 100 % Naoko Kanaya PDF (Victoria) 100 % Shengli Liu RA (Alberta) 100 % Rashid Mehdiyev RA (Montreal)´ 100 % Richard Soluk RA (Alberta) 50 % Hasko Stenzel RA (TRIUMF) 100 % Sarah Wheeler RA (Alberta) 100 % Monika Wielers RA (TRIUMF) 100 % T.B.A. RA (Carleton) 100 % T.B.A. RA (Montreal)´ 100 % T.B.A. RA (Toronto) 50 % T.B.A. RA (Toronto) 100 % T.B.A. RA (Simon Fraser) 50 % T.B.A. RA (Victoria) 100 % T.B.A. RA (TRIUMF) 100 %

Graduate Students

J.-P. Archiambault Ph.D. (Alberta) 100 % P.H. Beauchemin Ph.D. (Montreal)´ 100 % Guillaume Belanger M.Sc. (Carleton) 100 % Li Chen Ph.D. (Alberta) 50 % Claudiu Cojocaru Ph.D. (Alberta) 100 % Jonathan Ferland Fubiani M.SC. (Montreal)´ 100 % Gwenael Fubiani Ph.D. (Montreal)´ 100 % M.H. Genest Ph.D. (Montreal)´ 100 % Tayfun Ince M.Sc. (Victoria) 100 % H.-W. Jeong Ph.D. (Toronto) 100 % Andrew Hamilton Ph.D. (Alberta) 50 % Jeff de Jong Ph.D. (Alberta) 100 % Celine´ Lebel Ph.D. (Montreal)´ 100 % R. Mazini Ph.D. (Montreal)´ 100 % K. Martens Ph.D. (Toronto) 100 % F. Marullo Ph.D. (Montreal)´ 100 % J. Park Ph.D. (Toronto) 100 % Patrick Roy Ph.D. (Montreal)´ 100 % Warren Shaw M.Sc. (Victoria) 100 % Trischuk PIN 101982 3

Malachi Schram Ph.D. (Carleton) 100 % Tamara Starke M.Sc. (Victoria) 100 % Yushu Yao M.Sc. (Alberta) 100 % Wei-Yuan Ting Ph.D. (Alberta) 100 % Dan Vanderster M.Sc. (Victoria) 50 % T.B.A. M.Sc (Alberta) 100 % T.B.A. M.Sc (Alberta) 100 % T.B.A. M.Sc (Alberta) 100 % T.B.A. M.Sc. (Montreal)´ 100 % T.B.A. M.Sc. (Montreal)´ 100 % T.B.A. M.Sc. (Toronto) 100 % T.B.A. M.Sc. (Simon Fraser) 100 % T.B.A. M.Sc. (Victoria) 100 % T.B.A. Summer (Alberta) 100 % T.B.A. Summer (Alberta) 100 % T.B.A. Summer (Carleton) 100 % T.B.A. Summer (Carleton) 100 % T.B.A. Summer (Carleton) 100 % T.B.A. Summer (Montreal)´ 100 % T.B.A. Summer (Montreal)´ 100 % T.B.A. Summer (Simon Fraser ) 100 % T.B.A. Summer (Toronto) 100 % T.B.A. Summer (TRIUMF) 100 % T.B.A. Co-op (Victoria - 3 terms) 100 % T.B.A. M.Sc. (Carleton) 100 %

Engineering and Technical Infrastructure

Paul Birney Senior Technican (TRIUMF) 50 % Philippe Benoit Technican (TRIUMF) 100 % J. Berichon Technician (Montreal)´ 30 % Bill Burris Elect. Tech. (Alberta) 10 % Mircea Cadabeschi Engineer (Toronto) 100 % Keith Coley Draughtsman (Toronto) 100 % Phillipe Gravelle Technician (Carleton) 70 % Alisa Dowling Engineer (TRIUMF) 10 % Robert Henderson Scientist (TRIUMF) 10 % Lars Holm Sen. Elect. Tech. (Alberta) 20 % Fiona Holness Laboratory Assistant (Victoria) 100 % F. Hortop Designer (Carleton) 50 % Keith Hoyle Technican (TRIUMF) 100 % W. Jack System Manager (Carleton) 20 % Gaiane Karapetian Software physicist (Montreal)´ 50 % Roy Langstaff Engineer (TRIUMF) 100 % Trischuk PIN 101982 4

Mark Lenckowski Designer/Draftsman (TRIUMF) 30 % Ed Pattyn Senior Technican (TRIUMF) 100 % A. Levesque Electronics (Montreal)´ 30 % Jim MacKinnon System Manager (Alberta) 10 % Drew Price Elec. Tech. (Alberta) 50 % Ernie Neuheimer Electronics (Carleton) 40 % Paul Poffenberger Physicist (Victoria) 100 % Bill Roberts Electrical Engineer (TRIUMF) 10 % Jan Schaapman Elec. Tech. (Alberta/TRIUMF) 60 % Jan Soukup Engineer (Alberta) 70 % Vance Strickland Engineer (TRIUMF) 90 % Mike Thompson Technician (TRIUMF) 100 % Jan Van Uytven System Manager (Victoria) 50 % Kenneth Vincent Technologist (Toronto) 100 % Peter Vincent Technician (TRIUMF) 70 % Len Wampler Elect. Tech. (Alberta) 10 %

A. Project Summary

The Montreal´ and Toronto groups have been participating in the design, assembly and testing of the ATLAS inner detector for 5 years. Recently we have focused on the testing of pixel modules and calculations of the expected detector activation – important to assess detector maintenance scenarios after it has begun operation. These activities are a natural consequence of our experience in the characterisation of solid state sensors, detectors based on these technologies and our expertise in the radiation hardness of detector materials. A lack of financial support has recently led to the conclusion that we will not be able to participate in a meaningful way in the assembly and testing of the ATLAS pixel modules which are now in full production. An attractive alternative, that we have recently begun to consider, is the development and installation of the ATLAS beam loss monitors and beam abort system. The LHC has its own beam loss monitors that will trigger an abort if there is a failure in the accelerator system. However, these do not cover every possible situation. In particular, beam losses that could be very harmful to the ATLAS inner detector may not be full protected against. With our background in radiation hardness studies and radiation hard sensor materials we have begun to investigate the use of Chemical Vapour Deposited (CVD) diamond sensor material for beam loss monitoring applications. Here we request funds for the equipment necessary to prototype, radiation test and construct such a system for the ATLAS experiment. There is no other activity in this area, in ATLAS, so our efforts would have a high profile within the collaboration. We expect the associated operating costs to be covered by the on-going ATLAS-Canada operating grant. Trischuk PIN 101982 5

B. CVD Diamond Sensor Development – Toronto

The University of Toronto has been leading North American efforts to develop CVD diamond sensors suitable for use in high radiation environments since 1996. This project has resulted in prototype trackers [1] and pixel detectors [2] suitable for use in future high energy physics experiments – such as upgrades to ATLAS for higher luminosity running. While current materials have shown that the are suitable for use at the LHC we have continued to work with CVD diamond suppliers to optimise production techniques making the production of large area CVD diamond sensors economically viable and financially attractive for particle physics experiments. Recent advances in CVD diamond growth technology have made it possible to grown single crystal CVD samples – albeit small ones – on high pressure, high temperature mono-crystalline diamond substrates. This new material shows improved energy resolutions and larger signals for smaller applied bias voltages. It may be ideal for the dosimetry and beam abort applications discussed in this proposal. However its radiation tolerance remains to be confirmed.

(a) CVD Diamond Beam Monitors We propose to use CVD diamond sensors to monitor beam losses. These detectors have several advantages: they can be made small, they have a fast response and most importantly, they are radiation hard, exhibiting little or no leakage current even after irradiation. They present however a few technical problems: the signal collected can vary by ±30% over the volume of a sensor and the readout electrodes plated onto the surface of the sensor have deteriorated at the highest fluences – despite the fact that the diamond material itself is unaffected – as evidenced by the return to full signal capability if the readout electrodes are replaced after samples have been irradiated. The RD42 collaboration has made several improvements on the quality of the CVD detectors over the past few years. Working with the manufacturer Element6 [3], the collaboration has made a systematic study of readout electrode options and has managed to increase the collection volume. One of us (WT) has already been funded with a three year discovery grant to study the feasibility of diamond beam monitors and eventually an abort system for the Belle experiment. Figure 1 shows one of the two sensors that have been prepared for use in Belle along with the position of the two sensors mounted at KEK. The current grant provides enough support to develop simple current converters to monitors the beam induced activity in these sensors, interfacing the diamond current to the existing Belle beam monitoring readout system. It also provides support for two visits a year to KEK to upgrade the readout, collect the data and discuss the performance of the diamond sensors, relative to the silicon system that is currently used for the beam abort/protection system in Belle. This proposal will allow us to extend that work, perform radiation hardness tests suitable for sensors that we propose to put into the much higher radiation environment at the LHC and provide a sufficient number of sensors to properly equip the ATLAS interaction region and understand the beam losses. Further advantages of CVD diamond detectors used as radiation monitors include: their fast response, allowing them to trigger a beam abort quickly in case of excessive beam losses; and their vanishingly small leakage currents that will allow us to make a robust distinction between actual beam losses and detector noise. These two properties will mean that we trigger many Trischuk PIN 101982 6

Figure 1: a) A sensor similar to the one we propose to install in ATLAS. One can see the electrode on the surface and the cables that bias the detector and are used to readout the beam loss related current. b) The interaction region of the Belle experiment at KEK. Two diamond sensors can be seen mounted on the silicon support cone, at a distance of 35 cm from the interaction point. They can be at a radius of 4 cm (at the 2 O’Clock position and behind the large grey cables at the 9 O’Clock position). fewer aborts than a similar system based on silicon sensor technology that will have much higher leakage currents. The fast signal, stable, signal would also provide useful information in tuning the LHC under normal operating conditions – when losses are not dangerously high. An array of several dosimeters will also allow to make a three dimensional dose map, allowing us to refine our activation calculations (see below).

C. Pixel Module Studies – Montreal´

Two contributions to the ATLAS Pixel detector have been undertaking at the Universite´ de Montreal´ in the context of the ATLAS pixel detector: the construction of a test bench and simulation of activation of the ATLAS pixel detector.

(i) Pixel Test Bench The first aim of the test bench was to test silicon pixel detectors for charge collection and proper functioning of each pixel. To do we setup, a pixel silicon detector with a FE-B read-out interface provided by the ATLAS Pixel collaboration. The pixel detector is made of 2880 pixels of 50µm × 400µm and a width of 300µm. The read-out electronics of the pixel detector is linked to a computer. With the PixelDAQ 11.3 program, the user can select which pixels are active and therefore contribute to the read-out. By activating the internal trigger, the user can inject charge testing only the read-out electronics mounted on the pixel detector. Trischuk PIN 101982 7

The pixel detector itself is best tested with an external trigger. To do so, a solid ruthenium-106 source of 100 µCi was installed in the test area along with two surface barrier silicon detectors. The surface barrier silicon detectors in coincidence served as a trigger. The read-out electronics for these detectors are standard: pre-amplifier, amplifier, single channel analyser, coincidence and gate and delay generator. The single channel analysers select only the disintegration radiation of interest: electrons of energies higher than 2 MeV, roughly minimum ionising particles (mips) that traverse the pixel detector assembly. These particles will not stop inside the pixel detector but go through it, depositing approximately 80 keV in 300 µm of silicon. For the time being, only one surface barrier detector is used to trigger due to an amplifier deficiency. The read-out electronics will be replaced shortly with higher performance material. With both pixel and surface barrier detector were fully depleted, several tests were done. An example is illustrated in figure 2. With only one trigger detector, the average ratio counts/events triggered was 1%. This ratio will improve once the trigger system is fully operational. The concentration of hits in the middle part of the detector is due to the presence of a 2 mm thick plastic plate with a circular window placed between the pixel detector and the source. With these tests, it was possible to identify individual pixels that do not work properly. Fifteen pixels were found to have unsatisfactory results: thirteen pixels never worked and two pixels counted less than 0.01% of the maximum hits of each experiment. Bonding between the FE-B readout chip and the pixel sensor in the early ATLAS test-assembly we had available for test is thought to be the cause of this problem.

Figure 2: Output example of an external trigger test.

In short, the charge collection test bench is now operational. The most imminent improvements will be the replacement of the read-out electronics for the trigger detectors, the installation of an Trischuk PIN 101982 8

XY table allowing to test specific regions of the pixel detector (using a smaller collimator) and the addition of a holder to test pad detectors. The test bench can be easily adapted to test CVD detectors.

(ii) Activation Studies A simulation of the pixel module activation is continuing. The simulation is done using the program PYTHIA 6.2 to generate proton-proton collision products at 14 TeV. These products are propagated through the ATLAS inner detector geometry using GEANT4. GEANT4 has been improved in the past year to describe more adequately low energy interactions, which are mostly responsible for material activation, and to include the possibility of “measuring” the activity directly in the simulation. In the past year, the addition of the surrounding volumes has been completed (see figure 3). Events have also been generated successfully. The remaining difficulties lie in GEANT4 program. Its updates have slowed the progress on the study be requiring code adaptations. We are still in the process of verifying details of the simulation to ensure that it is accurate.

Figure 3: Geometry of the ATLAS detector implemented in the GEANT4 simulation.

D. Proposal

The development of CVD diamond beam dosimeters to be used as radiation monitors has already begun to be studied in BaBar and Belle at the high intensity e+e− B factories. We propose to Trischuk PIN 101982 9 continue this work on behalf of the ATLAS collaboration using the test bench in Montreal to characterise their operation. We would also perform hadron irradiations to ensure that the current generation of sensor material is adequate for ATLAS. Finally we will deploy a set of eight detector assemblies – four each in the forward and backward regions of ATLAS. This should provide an adequate set of measurements to characterise the beam losses in the ATLAS tracking volume and make well informed decisions about whether it is necessary to abort the beam to protect the tracking detectors. This will have an impact on the LHC beam loss monitoring group and provide us with a significant role in the ATLAS experiment.

(i) Equipment Requested Specifically, we request funds to acquire eight prototype CVD diamond sensors ($US 1,280 per cm2 sensor). We will metalise these with either single readout pads, or coarsely segmented ’pixel’ patterns. Either of these can be produced with relatively simple evaporation techniques. We will develop radiation hard packaging for these sensors, attempting to minimise leakage currents due to the surrounding material. We must irradiate these assemblies to ensure their survival at the very heart of the ATLAS experiment. While it may be possible to do irradiations parasitically with other ATLAS prototypes we know that we can obtain the beam time we need at facilities such as the one in Dubna. The costs for this beam time are included in this request. We further request support to develop readout boards that will adapt the diamond sensor signals to existing ATLAS beam monitoring readout systems. We do not envisage this being a fully custom radiation hard integrated circuit, but an adaptation of existing readout electronics. This will involve an initial round of prototyping and the production of the final readout system. Need more thought here. Finally, in the third year of this proposal we will develop support frames, to deploy the production beam monitors. In the last two years of the grant we request funds for a further twelve production sensors, eight to be installed and four spares.

Budget

Equipment 2004-05 2005-06 2006-07

Prototype Sensors 15,360 Metalisation 3,000 2,500 2,500 Packaging 2,000 2,000 500 Irradiation time 8,000 8,000 Electronics development 8,000 Support Mechanics for ATLAS 2,000 Production sensors 7,680 15,360 Production electronics 20,000 2,000 Cabling 8,000

Total Requested from NSERC $36,360 $40,180 $30,360 Trischuk PIN 101982 10

References

[1] First Measurements with a Diamond Microstrip Detector, F. Borchelt et al., Nucl. Instrum and Meth. A354, p318, (1995).

[2] The First Bump-bonded Pixel Detectors on CVD diamond, W. Adam et al., Nucl. Instrum. and Meth. A436 p326, (1999).

[3] Element6, King’s Park Ride, Ascot, Berkshire, SL5 8BP, United Kingdom.