1. SP- 41 magnet ZDC RPC (TOF) DC ST Target T0 detector MPD / NICA and BM@N / Nuclotron Experiments Picosecond Cherenkov detectors for heavy ion experiments at LHEP/JINR Vladimir Yurevich and Oleg Batenkov a Joint Institute for Nuclear Research, Dubna, Russia b V.G. Khlopin Radium Institute, St. Petersburg, Russia The modular Cherenkov detectors with picosecond time resolution are developed as main start and L0 trigger detectors for Au + Au collisions in future experiments MPD and BM@N at JINR for study of highly-excited and dense baryon matter in Au+Au collisions at energies of NICA collider and Nuclotron. The key element of BM@N setup is multilayer tracking system (silicon, GEM, straw tubes, drift chambers) placed behind the target. MPD experiment with beams of NICA collider The FFD consists of two arrays of Cherenkov modules at z = 75 cm from IP. The aim of the FFD is to provide Start signal for TOF detector Selection of Au+Au collisions at |z| ≤ 25 cm from IP L0 trigger Beam Target Vacuum pipe Detector modules T0 detector Start signal for TOF detector L0 trigger with selection of events on centrality Frontier Detectors for Frontier Physics 13 th Pisa Meeting on Advanced Detectors Au + Au, 2 A GeVAu + Au, 4 A GeV T0 detector performance Detector Module The modular arrays FFD/MPD and T0/BM@N detect high energy photons and charged particles via registration of induced Cherenkov radiation by MCP-PMTs in the modules. The detectors provide start pulse for TOF detector with time resolution σ < 50 ps and effective L0 trigger of Au+Au collisions. The module contains of aluminum housing, 10-mm Pb converter, quartz radiator with 4 bars 26.5×26.5×15 mm each, MCP-PMT XP85012/A1-Q, FEE board, and HV divider. The anode pads of MCP-PMT are joined into 2×2 cells. The FEE has 4 channels for processing pulses from anode pads and a single channel for pulse from MCP output. Each the chain consists of amplifier, shaper, and discriminator and produces analog and LVDS signals which are fed to SMA and HDMI connectors respectively. Beam Tests 1 2 3 4 5 6 7 8 1 – Pb plate / converter 2 – quartz radiator 3 – MCP-PMT 4 – FEE board 5 – module housing 6 – HV connector 7 – SMA outputs of analog signals 8 – HDMI cable (LVDS signals + LV) The characteristics of detector modules were studied with deuteron beam of Nuclotron at energies from 2.0 to 3.5 GeV/u. Two pairs of detector modules D1 – D2 and D3 – D4 were used in the test measurements. Three different readout electronics were applied: 1. DRS4 Evaluation Board V4 digitizers (PSI), 2. 5 GS/s digitizer CAEN mod.N6742, 3. VME module TDC32VL, 32-channel 25 ps multihit time stamping TDC (JINR). photons + pions The MPD is 4π-setup and it consists of various detectors for study of characteristics of numerous secondary particles produced in IP within a wide pseudo-rapidity interval. The T0 detector is modular Cherenkov detector on a base of the same modules used in FFD/MPD. The aim of T0 detector is to provide ab Fixed target experiment BM@N with beams of Nuclotron Au + Au, = 4 ÷ 11 GeV Au + Au, 2.0 ÷ 4.5 A GeV, 10 ion/s In both experiments the TOF detector is based on large area RPC arrays. The start signal comes from Fast Forward Detector (FFD) in MPD and T0 detector in BM@N. The TOF method is used for particle identification. At the present some different arrays with 12 and 20 modules are considered to define a final version of FFD modular array. The initial version used for study of detector performance has 12 modules with 48 channels per array. Study of detector performance with MC simulation at high intensity of Au beam with absence of any materials in beam line except Au target. To define a final detector design some different versions are considered. The initial version of T0 detector for study of detector performance has 12 modules placed around a target with 48 independent channels. Fast Forward Detector (FFD) 100% efficiency to trigger central and semi-central Au+Au collisions. The central collisions correspond to events with the largest number of hits and they can be selected by L0 trigger. FFD L R IP Current FFD design with 12 module arrays Efficiency to trigger Au+Au collisions by registration of photons and charged particles ( threshold =1000 Ch.ph.): ONE - a single FFD array, OR - any of two arrays, and AND - both FFD arrays Pulse height distributions for photons with energies of 50, 100, 200, and 500 MeV FFD performance Pulse height distribution via time of arrival in FFD for charged particles, Au+Au at = 7 GeV Pulse form measured with DRS4 Evaluation Board V4 TOF measurements with two pairs of the modules and DRS4 E.B.V4 TOF result (sigma) 33.5 ps Single detector resolution, σ 24 ps D1–D2D3–D4 ExperimentMPDBM@N DetectorFFDT0 Number of arrays21 Number of modules12 × 212 Number of channels48 × 248 Required time resolution, σ< 50 ps Min. bias triggerYes Central collision triggerYes Operation in magnetic field, B0.5 T MCP-PMT XP85012 /A1-Q 25 μm pore 8×8 anode pads 53×53-mm photocathode Quartz window = 5 GeV The time resolution of start signal improves as where N is a number of hits depending on beam energy and centrality of Au+Au collisions. The measurements with LVDS pulses and TDC32VL give time resolution of single detector channel of 35÷40 ps. Test in magnetic field of BM@N magnet T0 detector Layout of T0 detector inside BM@N magnet and a view of detector modules Operation of modules in magnetic field with B = 0.5 T was tested with a prototype of T0 detector. February – March 2015 The pulse height distributions and time resolution were studied with 3.5-GeV/u carbon beam. The C ions interacted with Cu target 10 mm diam.×7 mm. The modules detected secondary photons and charged particles. A beam Cherenkov detector with 11-mm quartz radiator generated start signals for TOF measurements. The time resolution of the start detector was σ = 27 ps. To restore the gain of MCP-PMT in magnetic field, HV was increased (+20 V for modules at 0° and 180°, and +250 V for modules at 60° and 120°). The time resolution obtained with CAEN digitizer and MCP output pulse is 57 ps and 110 ps for modules at 0° (180°) and modules at 60° (120°) respectively. A constant shift of pulses in time scale is observed due to an influence of magnetic field on electron path inside MCP-PMT. The data analysis is in progress. Photon multiplicity in FFD array at = 9 GeV as a function of centrality Current design of T0 detector Trigger performance of T0 detector for Au+Au collisions at different centrality for two beam energies 2 and 4 A GeV t t t t References 1. V.I. Yurevich, Nuclear Instruments & Methods in Physics Research A (2015), http://dx.doi.org/10.1016/j. nima.2015.01.006i. 2. V.I. Yurevich, O.I. Batenkov, et al., Physics of Particles and Nuclei Letters 10 (3) (2013) 258. Contact info: E-mail: yurevich@jinr.ruyurevich@jinr.ru LAQGSM + GEANT4 S. Lobastov Layout of detectors on MPD-test beam line and the Cherenkov modules D1 – D4 (without Pb converter) 50 32 100 52 200 67 500 74 E (MeV) ε (%) γ γ The efficiency of photon detection Energy spectrum of photons coming to FFD array from Au+Au at = 5 GeV Typical pulses on an oscilloscope screen 246810Time, ns 100 200 300 400 500 Pulse height, mV p π FFD 7 IP