6-7 October 2006 MPD Dubna, Russia Mixed Phase Detector (MPD) Joint Institute for Nuclear Research Conceptual project S.Afanasiev, V.Babkin, A.Baldin, S.Bazylev, V.Borisov, D.Driablov, V.Golovatyuk, A.Isupov, V.Krasnov, V.Ladygin, A.Litvinenko, Ju.Lukstinsh, A.Malakhov, E.Matyushevskiy, I.Migulina, N.Piskunov, E.Plekhanov, A.Shabunov, S.Shimansky, I.Slepnev, V.Slepnev, I.Tyapkin, S.Vokal, Yu.Zanevsky, P.Zarubin, L.Zolin.

6-7 October 2006 MPD Dubna, Russia Experimental setup should allow to measure: - Event-by-event fluctuations. The hadron yields and momenta should be analyzed event-wise in order to search for strong fluctuations which are predicted to occur in the vicinity of the critical endpoint and when penetrating the coexistence phase (the mixed quark-hadron phase) of the first order deconfinement phase transition. In order to subtract the (dominant) contributions from resonance decays one should measure the yields of the relevant short-lived hadron resonances. - Multistrange hyperons. The yields, spectra and collective flow of (multi) strange hyperons are expected to provide information on the early and dense phase of the collision as they are produced close to threshold. Therefore, these particles are promising probes of the nuclear matter equation of state at high baryon density. - HBT correlations. Observation of short correlations of π, K, p, Λ hadrons allows one to estimate the space-time size of a system formed in nucleus-nucleus interactions. Alongside with the increase of fluctuations, the spatial size of the system is expected to be enhanced at the phase transition getting smaller near the deconfinement point due to softening the equation of state (the "softest point" effect). - Penetrating probes. Measurements of dilepton pairs permit to investigate the in-medium spectral functions of low-mass vector mesons which are expected to be noticeably modified due to effects of chiral symmetry restoration in dense and hot matter. Specific properties of the σ -meson as a chiral partner of pions, which characterizes a degree of chiral symmetry violation, may be in principle detected near the phase boundary via a particular channel of σ -decay into dileptons or correlated γγ -pairs. Above a beam energy of about 15 AGeV also charmonium might be detectable. J/ Ψ mesons are a promising probe for the deconfinement phase transition. - Open charm. D-mesons probe the early phase of the collision and are sensitive to in-medium effects due to chiral symmetry restoration.

6-7 October 2006 MPD Dubna, Russia Setup overview Scheme of the MPD setup. TPC - Time Projection Chamber; SVS - Silicon Vertex tracking System; TRD - Transition Radiation Detectors; TOF - Time of Flight detectors; EC - Electromagnetic Calorimeters; LENS - magnetic focusing lens of collider

6-7 October 2006 MPD Dubna, Russia

6-7 October 2006 MPD Dubna, Russia Main components of proposed MPD setup: - Superconductive Magnet System (MAGNET COILS); - Vertex tracking System; - Central Arm; - Two Forward arms; Each Arm include Time Projection Chamber (TPC); Transition Radiation Detectors (TRD); Time of Flight detectors (TOF); Electromagnetic Calorimeters (EC).

6-7 October 2006 MPD Dubna, Russia 6.2 Superconductive Magnet System The superconductive magnet system is composed by two pairs of concentric coils and provides a field (1-2T) parallel to the beam. For the forward angle, the magnetic field is formed by iron cones and produces a radial magnetic field for the forward angle analysis. The primary physics-driven requirements for the central magnet design are: (i) No mass in the apertures of the spectrometer arms to minimize interactions and multiple scattering of particles produced in the primary collision and to minimize albedo from the magnet poles. (ii) Dense material near the collision point in the apertures of the forward arms to serve as hadron absorbers. (iii) Reasonably uniform field that could be mapped to a precision in the field integral of about 2 parts in (iv) Control over the radial field distribution to allow creation of a "zero field" region near R = 0. (v) Minimal field integral for the region R > 200 cm, the radius of the TPC. Field in the region of the photomultiplier tubes of the TOF and the Electromagnetic Calorimeter are also required to be low. (vi) The magnet must be easily moveable to allow access to detector components for commissioning, maintenance and replacement.

6-7 October 2006 MPD Dubna, Russia Silicon Vertex tracking System(SVS); The vertex tracking is based on highly segmented silicon pixel and microstrip detectors at mid-rapidity, and further silicon pixel detectors in the forward direction. Three internal central layers of SVS are constructed from silicon pixel detectors and three outer layers are built from microstrip silicon detectors with a pitch from 25 to 50 mkm. They will be arranged in two half-shells and will cover approximately −5 o <  <40 o and almost 2  in azimuth. Pixel sensor technology is essential for the resolution of the high track density in heavy ion collision in the internal layer. Microstrip detectors also could be used in the more outward layers where the occupancies are less severe. The forward silicon detectors will consist of four pixel cones per side that match the geometrical acceptance

6-7 October 2006 MPD Dubna, Russia A large Time Projection Chamber (TPC) is proposed as a main tracking device for the detector at future collider. The ambitious physics program poses unprecedented requirements on the precision of the TPC. This modern experiments plan to use TPC at high charged particles multiplicities of up to 800 per event. The modern experiments are propose to work at unprecedented high multiplicities up to 8000 per unit rapidity - ALICE TPC (CERN/LHCC 2000–001). Another example of the tracking system is the STAR TPC which is able routinely reconstructs more than 3000 tracks per one event (M.Anderson et al., Nucl.Instr.Meth.A499 (2003) 659). Tracking System TPC operation parameters Centarl TPC - diameter = 5.6m - lenght = 2.0m Forward TPC - diameter 1 = 1.5m diameter 2 = 5.0m - lenght = 2.0m Drift time -=50  s

6-7 October 2006 MPD Dubna, Russia The STAR TPC The STAR detector contains a large, cylindrical, Time Projection Chamber (TPC) as its primary detector element. The TPC has an active volume that extends from -1.8 to +1.8 units of pseudo-rapidity with full azimuthal coverage. It sits inside a large solenoidal magnet which is designed to run with a.eld between 0 and 0.5 T. The event multiplicities excess of 3000 tracks per event. The momentum resolution is 2% at 500 MeV/c: The two-track resolution for HBT pairs of tracks is 2.5 cm. The dE=dx resolution is Excellent It able to separate the pion band and the proton band at momenta up to 1.3 GeV/c and the resolution is 7.5%. A L I C E TDR of the Time Projection Chamber To cover this acceptance the TPC is of cylindrical designwith an inner radius of about 80 cm, an outer radius of about 250 cm, and an overall length in the beam direction of 500 cm. Two-track resolution: a resolution in relative momentum of a few ( _ 5) MeV/c can be performed. Resolution in dE/dx: For hadron identification a dE/dx resolution of 8% is desirable, following the experience of NA49. Track matching capability to ITS and TOF: Should be 85%– 95%. Electronics: At about channels the front-end electronics

6-7 October 2006 MPD Dubna, Russia

6-7 October 2006 MPD Dubna, Russia Particle identification with TPC An strength of the tracker in solenoid magnetic field at MPD is a large and uniform acceptance capable to measure and to identify substantial fraction of the particles produced in heavy-ion collisions. For stable charged hadrons, the TPC provides pions and kaons (protons) identification up to p t ~ 0.7 (1,1) GeV/c by ionization energy loss (dE/dx). A TOF system with a time resolution of <100 ps is able to identify pions and kaons (protons) up to p t ~ 1.6 (3.0) GeV/c, as demonstrated in Fig.. Combination of dE/dx in the TPC and velocity measurements by TOF provides a strong tool for the dilepton measurements.

6-7 October 2006 MPD Dubna, Russia The Transition Radiation Detector (TRD) will provide, in conjunction with data from the TPC and EC detectors, sufficient electron identification to measure, in the dielectron channel, the production of light and heavy vector-meson resonances for U- U collisions at the NICA, as well as allow to study the dilepton continuum. In addition, the electron identification provided by the TPC and TRD at relatively large transverse momenta (p t 1 GeV/c) can be used, in conjunction with the impact- parameter determination of electron tracks in the ITS, to determine the overall amount of open charm and open beauty produced in the collision. With a similar technique one can also separate directly produced J  mesons. Straw tubes TRD TRD system Design goals e/π discrimination of > 100 (p > 1 GeV/c) High rate capability up to 150 kHz/cm 2 Position resolution of about 200 μm. Large area (  50m 2, 3 layers) MWPC

6-7 October 2006 MPD Dubna, Russia Lead-Scintillator Calorimeter The Pb-scintillator electromagnetic calorimeter is a shashlik type samplingcalorimeter made of alternating tiles of Pb and scintillator consisting of 1500 individual towers and covering an area of approximately 18 m 2. The basic building block is a module consisting of four (optically isolated) towers which are read out individually. The PbSc calorimeter has a nominal energy resolution of 8.1%/  E(GeV ) +2.1% and an intrinsic timing resolution better than 200 ps for electromagnetic showers Electromagnetic Calorimeter. (EC)

6-7 October 2006 MPD Dubna, Russia ZDC

6-7 October 2006 MPD Dubna, Russia Table 8.4. Schedule of MPD group II realization

6-7 October 2006 MPD Dubna, Russia

6-7 October 2006 MPD Dubna, Russia Summary Mixed Phase Detector (MPD) - operate at the energy of beams 2.5 x 2.5 GeV/u; - work at the luminosity of the heavy ion beams up to cm -2 s -1 for U+U; - has practically 4  geometry; - has minimum of passive matter in the detector volume; - allow to measure high multiplicity events, up to 1000 particles/event; - to separate e, , K, p particles in range 200<P<2000 MeV/c; - to measure lepton-pairs and  -pairs; This setup can be use for solution of fundamental scientific questions : the nuclear matter equation-of-state at high baryonic densities; the in-medium properties of hadrons; space-time evolution of nuclear interaction; the phase transitions; the QCD critical endpoint; + Polarization studies at new facility

6-7 October 2006 MPD Dubna, Russia Thanks for attention!

6-7 October 2006 MPD Dubna, Russia