E.Kistenev Calorimetry in QGP studies at RHIC Siena, Italy, October 2008 Innovative Particle and Radiation Detectors 1
Collider facility at BNL : RHIC RHIC and Its Experiments RHIC relativistivic-heavy ion program BRAHMS & PP2PP PHOBOS PHENIX Beam Energy = 100 GeV/u Lave per IR = 2 1026 cm-2 sec-1 RHIC spin physics program RHIC pc polarimeter Siberian snakes PHOBOS Absolute Polarimeter (H jet) BRAH PP2PP Lmax = 2 x 1032 cm-2s-1 STAR 70% Beam Polarization PHENIX 9 GeV/u BOOSTER Q = +79 50 < s < 500 GeV STAR Spin rotator AGS TANDEMS Pol. Proton Source 500 ma, 300 ms Partial Siberian Snake LINAC BOOSTER AGS 200 MeV Polarimeter 1 MeV/u Q = +32 Siberian sn Spin rotator AGS Internal Polarimeter AGS pc polarimeter Rf Dipoles STAR RHIC: Two concentric superconducting magnet rings, 3.8km circumference Achieved configuration: Start of construction: January 1991 Au+Au: s = 130 and 200 Ge First collisions of Au-Au ions: June 2000 d+au: s = 200 GeV First collision of trans. polarized protons: December 2001 p+p: s = 200 GeV First collisions of long. polarized protons: May 2003 2
Experiments are different and. very competitive High resolution limited acceptance High rate capability Central arm Tracking Superb EM Calorimetry Particle Identification Forward Muon Arms: Muon tracker, muon identifiers MUON ARMS CENTRAL ARMS MUON ARMS CENTRAL ARMS Baseline -3-2 2-1 3 0 1 3
PHENIX today is facing the limits set by π0 extraction The Matter is Very Opaque. π0 is Suppressed out to 20 GeV/c Hadron are suppressed Direct photons are NOT ε > 15 GeV/fm3; dng/dy > 1100 4
and by acceptance S.Brodsky STAR 5
Constrains & opportunities 2π 1997 FC -3 0 SVTX -2-1 0 1 MPC MPC 2011 SVTX EMCAL φ c o vera g e EMCAL FC 2 3 EMCAL 6 r
How to High density calorimetry to optimize space use; Short moliere radius so showers are resolved; Fine longitudinal segmentation to identify electromagnetic showers from hadronic background; High resolution position sensitive detectors to resolve fully overlapped showers; Tracking capabilities to allow for central- and muon spectrometer tracks association to tracks in the calorimeter; High rate and fast triggering capabilities. 7
Project evolution -W-plates of 4 mm and 11mm -20 layers of Si pads Technical proposal -4 layers of strips (2X+2Y) Towers are 15x15 mm2 Recent -construction & funding staging γ/π0 identifier Segmented Electromagnetic Calorimeter (preshower) 4 mm W plates everywhere 21 layer of ~500µ Si pads (3 in hybrid preshower, 9 in each em segment) 4 layers of 300µ 0.5 mm wide Si strips (2X+2Y) 8
New development Si-Sc hybrid option - energy resolution: 23% -> 14% at 1 GeV -2 mm W plates everywhere - constant term: 2% -> 0.5% -Si in the first segment (<4 X0) - em depth: 14 X0 -> 20 X0 or more -Sc everywhere else 9
Implementation: W absorbers and Si readout 10
π0 s 2X0 Correlator: convolution of shower shape with actual strip energies 7X0 2X0 X/Y correlators (Layer 0) Strip energies (Layer 0) X/Y correlators (Layer 1) Strip energies (Layer 1) X-axis: fired strips relative to hit position. Hit position is at the center of x-axis in the correlator graphs, and only approximately at the center in the actual ROI graphs 3X0 11
Calorimeter as designed will track particles, measure energies, discriminate between em and hadronic showers discriminate between single and overlapping photons EM1 Catcher Normalized dσ/de EM0 All hadrons Showers in NCC Showers in EM-NCC Passed as em-showers Energy [GeV]12
Showers due to overlapped photons from p0 s in the 7-30 GeV/c range Showers due to single photons in 7-30 GeV/c range M(shower) [Gev] 13
Discriminating between photons and π0 s E(tower)/E(hit) 3 segments: 7+7+25 X0 15x15 mm2 towers EM0 EM1 0.5x62 mm2 strips HAD E(strip) [GeV] D[towers] from hit point 2X0 3X0 14
Easy to build Si based calorimetry PADS 15
XY-strip layers Y Scale 4:1 X Scale 1:1 Capacitors 0603: 0.8mm Resistors:0.8mm Pitch Adapter Conn. DF-30-34 1.0mm SVX4 Gold-plated copper foil Sub-sensor substrate Carrier board 16
CERN 2007 17
CERN2007 Preamp hybrid (8ch) CERN 2007 FPGA Preamp crate (6x112 ch)) ADC Receiver/ shaping Signals from Preamps 64 ch ADC board 18
Summary EMC calorimeters at RHIC served clean samples of p0 s and direct photons which were used to unambiguously identify the creation of QGP in HI collisions; EMC also served as a particle Id tool to identify electrons in the PHENIX central arms (J/Y, low mass lepton, pairs, nonphotonic electrons); PHENIX fully developed high density, high granularity W-Si tracking calorimeters to further extend acceptance of the calorimeters; R&D program will culminate with test-beam experiment (protobrick) planned for this winter; Construction project will be optimized to match physics, funding realities and RHIC plans. 19