The aim of this JRA is to perform R&D for prototypes of advanced particle detectors for hadron physics exploiting the strengths of the new photon sensor SiPM and pushing against the present deficiencies. The important tasks of investigation with the SiPM sensor are the following:


 Description of work and role of partners

Task 1. Cherenkov light detection with single photon readout
We develop a 64-pixel photo sensor matrix for working in high magnetic fields without the lifetime limits due to integrated anode currents. The principal difficulty of SiPM for this application is the single-photon equivalent
noise that amounts to 100 kHz up to a few MHz depending on the detector type and on the operating conditions in particular the temperature. This noise can be overcome for the Cherenkov event, by implementing a proper majority filter. We plan to study the majority filter technique by using a 16-sensor readout with available electronics. Then a matrix of 8 x 8 SiPM sensors (arranged in a 50 x 50 mm2 matrix similar to a multi-pixel photomultiplier) will be constructed. An efficient light concentrator which bridges ~7 x 7 mm2 cell size to the 3 x 3 mm2 sensitive area of the sensor, will be designed and constructed. Such a module will be used to study the trigger scenario for coincident few-photon events. Considering the progress in sensor technology a 8x8 matrix with full sensor coverage, will also be evaluated. The challenge is to achieve a good timing resolution at low light level. The key is cooling the device, significantly reducing the dark noise. The prototype SiPM matrix contains 64 channels implying that a high-density readout system has to be developed. The readout system should preferably integrate specific feature for the SiPM, namely individual voltage regulation and temperature control. The leading institutions in this sub-project are GSI, OeAW, IFIN-HH and UGlasgow. Responsible for the evaluation of the full sensor matrix will be JINR, CUNI, and Zecotek Photonics.

Task2: Theoretical model developments and modelization in Monte Carlo
Using inorganic scintillating fibers a position sensitive planar fiber array for fast triggering for hadronic and electromagnetic probes will be developed together with the proposed JRA WP21 LYSOFiber. The selection and
characterization of SiPM sensors matched to the LYSO fibers will be the task in this JRA. Involved institutions are JLU, SMI, INFN-LNF and INFN-Pi. In addition we try to reactivate the production of crystalline fibers by the Institute for Solid-State Physics, Chernogolovka, Russia (GSI, PIG-JLU, JINR).
Based on the experience gained in the framework of HadronPhysics2 WP28, we plan to pursue the activity with
organic scintillating fibers and bring it in a full prototype detector. The leading activities will be: a) the design, construction and test of a prototype for a trigger/tracker system based on 4 layers of 30 scintillating fibers in a very compact geometry, b) integrated readout electronics, able to deliver timing resolutions below 100 ps, c) a feed-back system able to stabilize the SiPM working point, correcting for the temperature and gain variations, d) compact and integrated power supplies with stability in the order of 10 mV. The prototype is going to be tested on electron, positron and hadron beams and in the presence of strong magnetic fields. The final aim is the delivery of a very compact fiber detector system, occupying a reduced space, fast and stable, able to perform timing measurements as well as assist tracking too. Such system is going to be a central detector unit both in SIDDHARTA-2 and AMADEUS experiments at DAFNE. The leading institutions in this sub-project are LNF-INFN and OeAW. IFIN-HH will play an important role in the feedback system and Slow Controls.
The calorimetric applications of wavelength shifting fibers will be the main subject of research by JINR, CUNI, assisted by Zecotek Photonics. After the successful construction and demonstration of the optical head in a Shashlik calorimeter module, work will be concentrated on the integrated design and construction of 3x3 MAPD matrix with light concentrators, temperature stabilization and preamplifiers. The idea is to have a hybrid chip (~15x15 mm2) made of non-resistive but heat-conductive material with one Peltier element on the back, 3x3 MAPD with Winston cones at the face and possibly also preamplifiers. Test of different materials and chip design will be done in first year, production of a small number of chip samples and individual sample tests are foreseen for the second year. The demonstration in the calorimeter module environment should conclude the development.

Task 3. Ultra-fast timing with plastic scintillators for TOF-applications
The optimization of the time resolution of charged particle detectors requires efficient collection of primary photons. The SciTil, as proposed for PANDA, should be made of much thinner scintillator material than the originally proposed timing barrel using long slabs. Subsequently, the number of primary photons is much smaller. The development of the SciTil first needs a full-scale Monte Carlo simulation of scintillator tiles. The parameters such as size, positioning of sensors for a spatially smooth signal response have to be optimized. This work is being done at GSI. The results have later to be validated by experiment in which GSI, INR and OeAW will be the leading institutions. The collaboration with BARC (Mumbai) within PANDA to build the SciTil is also being pursued. The design of dedicated readout electronics is the other important task of the project. If the SiPM from Hamamatsu will be used, a relatively simple possible solution is the design of a 4 (or 8) channel ASIC for n-type silicon sensors similar to the B-ASIC for p-type sensors from Politecnico Bari. INFN Pisa wil be responsible for the development. The work on the TOF wall is mainly performed at PNPI and UJ including radiation hardness tests.
The leading institutions will be GSI, INFN Pisa, UJ, PNPI, UGlasgow and JNR. The other institutions will contribute to the construction of the prototype, to the test measurements and their evaluation.