B. Seitz

Energy Resolution and Temperature Dependence of Ce:GAGG Coupled to

Scintillators are a critical component of sensor systems for the detection of ionizing radiation. Such systems have a diverse portfolio of applications from medical imaging, well logging in oil exploration, and detection systems for the prevention of the illicit movement of nuclear materials. The rare earth element cerium is an ideal dopant for a variety of host scintillating materials due to the fast 5d1 → 4f radiative transition of Ce3+. Cerium-doped gadolinium aluminium gallium garnet (Ce:GAGG) is a relatively new single crystal scintillator with several interesting properties. These include high light yield, an emission peak well-matched to silicon sensors, and low intrinsic energy resolution. Moreover, the material has high density and is nonhygroscopic. In this paper, we review the properties of cerium-doped GAGG and report energy-resolution (ER) measurements over the temperature range -10°C to +50°C for 3 × 3 × 30 mm3 Ce:GAGG crystals optically coupled to a silicon photomultipler (SiPM) sensor with a 3 mm × 3 mm active area. In addition, the linearity of the scintillator-SiPM response as a function of gamma energy is reported.

{\hbox {3}}\ \hbox{mm} \times {\hbox {3}}\ \hbox{mm}

Silicon Photomultiplier (SiPM) detectors are investigated world-wide as a suitable replacement for the conventional vacuum based PhotoMultiplier Tube (PMT) and are enabling applications otherwise not possible with PMT detectors. Progress in recent years has been substantial with SiPM detectors pushing the boundaries in energy and time resolution as well as photon detection efficiency and active surface area. In this paper we report on the performance of a gamma detector comprising latest generation SiPM detectors from SensL coupled to novel Cerium doped Gd3Al2Ga3O12 (GAGG) scintillators from Furukawa, Japan. Both 3mm×3mm N-on-P and P-on-N SiPM detectors have been optically coupled to 3mm×3mm×30mm crystals. An energy resolution (662 keV Cs-137) of 9.4% has been measured for GAGG crystal coupled to a 3mm×3mm N-on-P SiPM detector.

Silicon Photomultipliers

The Focussing-Lightguide Disc DIRC will provide crucial Particle Identification (PID) information for the PANDA experiment at FAIR, GSI. This detector presents a challenging environment for reconstruction due to the complexity of the expected hit patterns and the operating conditions of the PANDA experiment. A discussion of possible methods to reconstruct PID from this detector is given here. Reconstruction software is currently under development.

Performance evaluation of novel SiPM for medical imaging applications

One of the key detectors of the upcoming ANDA experiment for particle identification will be the Focussing-Lightguide Disc DIRC, based on a novel detector technique. It will use a fused silica disc as a solid radiator to generate Cherenkov light by the passing of charged particles. These photons will be transported by total-internal-reflection to the rim, where LiF crystals will be used to perform dispersion corrections. Focussing lightguides will map propagation angles to spatial positions on the surface of photon detectors. Fast single photon detection devices will be used to measure azimuthal angles and spatial positions, which can be used to reconstruct kinematic properties of the passing particles. The expected average interaction rate of 20 MHz yields a photon detection rate of 1.3 MHz, as it is foreseen to use 128 MCP-PMT, each with 32 channels, for continuous readout. Moderate timing resolution of 300 ps improves signal from noise separation. The readout design requirements for the Focussing-Lightguide Disc DIRC will be introduced. The current candidate for implementation of the front-end readout electronic system will be described and several alternative readout scenarios will be discussed. Finally, a summary and an outlook for further developments and tests will be given.

Reconstruction methods — PANDA Focussing-Lightguide Disc DIRC

Efficient PET scanners rely on inorganic scintillation crystals paired with efficient photon detectors. New PET machines are increasingly design to coregister PET with MRI signals, which calls for a compact detector design insensitive to magnetic fields. The advent of digital SiPM in particular promises a natural design route for a an MRI compatible PET brain dedicated scanner. We study the response of LYSO:Ce, GAGG:Ce and BGO coupled with two modules of Philips PDC 3200. We will present the characterisation of the dSiPM response on terms of breakdown voltage, dark count rate and optical crosstalk. The energy resolution as a function of distance and coincidence time lution as a function of temperature for these three materials will be shown. METHODOLOGY Both single (3mm x 3mm x 30mm) and block (30mm x 30mm x 20mm) scintillation crystals were optically coupled to dSiPM and placed facing each other inside a light tight climate chamber with a Na22 source.

The front-end readout electronics for the P̄ANDA Focussing-Lightguide Disc DIRC

Silicon Photomultipliers (SiPM) have shown great promise as a suitable replacement for conventional vacuum based Photomultiplier Tubes (PMT). Progress in recent years has been vast with SiPM sensors pushing the boundaries in energy and timing resolution as well as photon detection efficiency and active surface area. In this study we report the energy resolution and linearity of two novel scintillator crystals, Cerium doped Gd₃Al₂Ga₃O₁₂ (Ce:GAGG) and Praseodymium doped Lu₃Al₅O₁₂ (Pr:LuAG), readout by three different types of 3 × 3 mm² silicon photomultiplier sensors produced by SensL (MicroFM, MicroFB, MicroFC). Such a scintillator-SiPM architecture has applications in pre-clinical and clinical medical imaging modalities such as Positron Emission Tomography (PET). N-on-P (M series), P-on-N (B series) and low-noise P-on-N (C series) versions of the SiPM sensor platform have been coupled to the crystals and the response characterized over a range of gamma energies and detector bias values. A saturation-corrected energy resolution of 11.7% was achieved for a MicroFM device coupled to a 3 × 3 × 30 mm³ Ce:GAGG crystal at 20°C. An energy resolution of 16.1% was obtained for a MicroFB device optically coupled to to a 3 × 3 × 30 mm³ Pr:LuAG crystal at 20°C.

EP-1445: Performance evaluation of scintillators for SiPM PET/MRI Brain Imaging

The Focusing Disc DIRC is a novel detector concept for particle identification based on the detection of internally-reflected Cherenkov light. A thin synthetic silica disc of 1 m radius will be used as radiator and for light transportation. At the rim LiF bars are foreseen to passively correct for dispersion. Focusing elements map the angles of the propagating photons to spatial positions on the focal plane covered with position sensitive photon detection devices. This novel 2D(+1t) detector concept will contribute to the outstanding particle identification performance of the general purpose PANDA detector. The aims of the PANDA experiment are to address fundamental questions of the strong force, to explore the structure of the nucleon and to search for new matter. The technical design, the current status of the development and recent results from prototype test experiments for the Focusing Disc DIRC are presented.