The ABCD3TA is a 128-channel ASIC with binary architecture for the readout of silicon strip particle detectors in the Semiconductor Tracker of the ATLAS experiment at the Large Hadron Collider (LHC). The chip comprises fast front-end and amplitude discriminator circuits using bipolar devices, a binary pipeline for first level trigger latency, a second level derandomising buffer and data compression circuitry based on CMOS devices. It has been designed and fabricated in a BiCMOS radiation resistant process. Extensive testing of the ABCD3TA chips assembled into detector modules show that the design meets the specifications and maintains the required performance after irradiation up to a total ionising dose of 10 Mrad and a 1-MeV neutron equivalent fluence of 2×1014 n/cm2, corresponding to 10 years of operation of the LHC at its design luminosity. Wafer screening and quality assurance procedures have been developed and implemented in large volume production to ensure that the chips assembled into modules meet the rigorous acceptance criteria
In order to exploit the advantages of ion-beam therapy in a clinical setting, delivery verification techniques are necessary to detect deviations from the planned treatment. Efforts are currently oriented towards the development of devices for real-time range monitoring. Among the different detector concepts proposed, Compton cameras are employed to detect prompt gammas and represent a valid candidate for real-time range verification. We present the first on-beam test of MACACO, a Compton telescope (multi-layer Compton camera) based on lanthanum bromide crystals and silicon photo-multipliers. The Compton telescope was first characterized through measurements and Monte Carlo simulations. The detector linearity was measured employing (22)Na and Am-Be sources, obtaining about 10% deviation from linearity at 3.44 MeV. A spectral image reconstruction algorithm was tested on synthetic data. Point-like sources emitting gamma rays with energy between 2 and 7 MeV were reconstructed with 3-5 mm resolution. The two-layer Compton telescope was employed to measure radiation emitted from a beam of 150 MeV protons impinging on a cylindrical PMMA target. Bragg-peak shifts were achieved via adjustment of the PMMA target location and the resulting measurements used during image reconstruction. Reconstructed Bragg peak profiles proved sufficient to observe peak-location differences within 10 mm demonstrating the potential of the MACACO Compton Telescope as a monitoring device for ion-beam therapy.
In this contribution, new developments on the silicon photomultipliers (SiPM) fabricated at FBK-irst (Trento, Italy) are reported. With respect to the first series of devices produced in 2005/2006, there have been major improvements on both the the layout and the technology. Concerning the first aspect we fabricated SiPMs with increased fill factor and with different geometries (square/circular devices, arrays and matrices of SiPMs) to meet the requirements of different applications. Concerning the technology, we identified a process technique able to reduce significantly the dark count rate. In this paper we will describe the main electro-optical characteristics of these devices. I. INTRODUCTIONN the past few years a growing attention has been devoted to a solid state version of the photo-multiplier tube (PMT), generally referred to as the silicon photomultiplier (SiPM). Compared to PMTs it presents important advantages, such as: compactness, ruggedness, low operational voltage, insensitivity to magnetic fields and low cost. On the other hand, a lot of development is still needed to reach both the noise level (dark count rate) of a PMT as well as to increase the area covered by the device. FBK-irst (former ITC-irst, Trento) have been developing this device in its own fabrication laboratory since 2005 [1,2]. This is done in collaboration with INFN, which is mainly interested in the application of the sensor in high-energy physics, nuclear medicine and astro physics. At the 2006 IEEE Nuclear Science Symposium we presented the electro-optical characteristics of the first prototypes of Silicon Photomultipliers produced at FBK-irst, (see [3]). The devices under test had an area of 1x1mm 2 with 625 microcells. The fill factor was not optimized yet and its maximum value was about 30%. The electrical characteristics of such devices can be summarized as follows:• Breakdown voltage of about 30V;Manuscript received November 21, 2007.
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