C. Colledani

Review of the development of diamond radiation sensors

Abstract Diamond radiation sensors produced by chemical vapour deposition are studied for the application as tracking detectors in high luminosity experiments. Sensors with a charge collection distance up to 250 μm have been manufactured. Their radiation hardness has been studied with pions, proton and neutrons up to fluences of 1.9×10 15 π cm −2 , 5×10 15 p cm −2 and 1.35×10 15 n cm −2 , respectively. Diamond micro-strip detectors with 50 μm pitch have been exposed in a high-energy test beam in order to investigate their charge collection properties. The measured spatial resolution using a centre-of-gravity position finding algorithm corresponds to the digital resolution for this strip pitch. First results from a strip tracker with a 2×4 cm 2 surface area are reported as well as the performance of a diamond tracker read out by radiation-hard electronics with 25 ns shaping time. Diamond pixel sensors have been prepared to match the geometries of the recently available read-out chip prototypes for ATLAS and CMS. Beam test results are shown from a diamond detector bump-bonded to an ATLAS prototype read-out. They demonstrate a 98% bump-bonding efficiency and a digital resolution in both dimensions.

A submicron precision silicon telescope for beam test purposes

Abstract A precise and compact silicon microstrip detector telescope designed to provide reference information for charged particle tracks has been constructed. First operation results are presented. A signal over noise ratio higher than 100 has been obtained, resulting in a spatial resolution of 1.4 μm per detector, for a readout pitch of 50 μm. At a position in the center of the telescope, a track extrapolation error of 0.7 μm can be obtained for reconstructed tracks.

Radiation hardness studies of CVD diamond detectors

Abstract The inherent properties of diamond make it an ideal material for tracking detectors especially in the high rate, high radiation environments of future colliders such as the LHC. In order to survive in this environment, detectors must be radiation hard. We have constructed charged particle detectors using high quality CVD diamond and performed radiation hardness tests on them. The signal response of diamond detectors to ionizing particles is measured before and after irradiation. Diamond detectors have been exposed to 60 Co photons at Argonne National Laboratory, 300 MeV/ c pions at PSI, 500 MeV protons at TRIUMF and 5 MeV alpha particles at Los Alamos National Laboratory. The results show that CVD diamond is an extremely radiation hard material well suited for particle detector production.

First test results Of MIMOSA-26, a fast CMOS sensor with integrated zero suppression and digitized output

The MIMOSA pixel sensors developed in Strasbourg have demonstrated attractive features for the detection of charged particles in high energy physics. So far, full-size sensors have been prototyped only with analog readout, which limits the output rate to about 1000 frames/second. The new MIMOSA 26 sensor provides a 2.2 cm2 sensitive surface with an improved readout speed of 10,000 frames/second and data throughput compression. It incorporates pixel output discrimination for binary readout and zero suppression micro-circuits at the sensor periphery to stream only fired pixel out. The sensor is back from foundry since february 2009 and has being characterized in laboratory and in test beam. The temporal noise is measured around 13-14 e- and an operation point corresponding to an efficiency of 99.5±0.1 % for a fake rate of 10-4 per pixel can be reached at room temperature. MIMOSA 26 equips the final version of the EUDET beam telescope and prefigures the architecture of monolithic active pixel sensors (MAPS) for coming vertex detectors (STAR, CBM and ILC experiments) which have higher requirements. Developments in the architecture and technology of the sensors are ongoing and should allow to match the desired readout speed and radiation tolerance. Finally, the integration of MAPS into a micro-vertex detector is addressed. A prototype ladder equipped, on both sides, with a row of 6 MIMOSA 26-like sensors is under study, aiming for a total material budget about 0.3% X0.

Pulse height distribution and radiation tolerance of CVD diamond detectors

The paper reviews measurements of the radiation tolerance of CVD diamond for irradiation with 24 GeV/c protons, 300 MeV/c pions and 1 MeV neutrons. For proton and neutron irradiation, the measured charge signal spectrum is compared with the spectrum calculated by a model. Irradiation by particles causes radiation damage leading to a decrease of the charge signal. However, both the measurements and the outcome from the model shows that for tracker applications this drawback is at least partly counterbalanced by a narrowing of the distribution curve of the charge signal. In addition, we observed after proton irradiation at the charge signal spectrum a decrease of the number of small signals. As a result, the efficiency of a CVD diamond tracker is less affected by irradiation than the mean charge signal. (11 refs).

Recent results from the RD42 Diamond Detector Collaboration

Abstract Diamond, as the hardest material known, has an extremely high binding energy suggesting that it will be a radiation hard material. Given that it is also a semiconductor, one is led to believe that diamond might perform well as a high resolution semiconductor tracking detector in very hostile radiation environments in which more conventional detectors would fail. In this paper we, the RD42 Diamond Detector Collaboration, review the progress that we have made in the development of chemical vapor deposition (CVD) diamond as a detector material, its radiation hardness, and the performance we have achieved with diamond tracking detectors.

One micron spatial resolution with silicon strip detectors

Abstract We have tested two 25 μm pitch DC-coupled p-side silicon microstrip detectors with low noise VIKING readout, in a 100 GeV π − beam at CERN. Two independent analyses, using the same data set, obtained the following results: The signal to single channel noise ratio was 71 to 1 (75 to 1), and the spatial resolution was measured to be σ = 1.25 μ m ( σ = 1.30 μ m) for tracks perpendicular to the surface.

Silicon ultra fast cameras for electron and γ sources in medical applications

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.

Radiation tolerance of CVD diamond detectors for pions and protons

Abstract The paper gives new results on the radiation tolerance of CVD diamond for irradiation with 300xa0MeV/c pions and 24xa0GeV/c protons. The measured charge signal spectrum is compared at several irradiation levels with the spectrum calculated by a model. Irradiation by particles causes damage leading to a decrease of the charge signal. However, both the measurements and the outcome from the model show that for tracker applications this drawback is at least partly counterbalanced by a narrowing of the distribution curve of the charge signal. As a result, the efficiency of a CVD diamond tracker is less affected by irradiation than the mean charge signal.

Neutron irradiation of CVD diamond samples for tracking detectors

Abstract Diamond may make an excellent substrate for a tracking device in the near future, especially at colliders like LHC, where extreme running conditions are expected (high rates and high radiation levels). We report on neutron irradiation of several CVD-diamond samples at the ISIS facility (Rutherford Appleton Laboratory), which provides a fast neutron spectrum similar to that expected in a high luminosity collider experiment like CMS. We measured beam-induced currents and charge collection of diamonds exposed to fluences in excess of 10 15 n/cm 2 (peaking at 1 MeV), which should be the maximum value of the ten years total fluence at the design LHC luminosity. Physical hypotheses for the interactions of neutrons on CVD-diamond are proposed.