Status of Projectile Spectator Detector A.Kurepin (Institute for Nuclear Research, Moscow) I. Introduction to PSD. II. Conception and design. III. Development and production of PSD prototype. IV. Future plans.

PSD in CBM setup. PSD Very Forward Hadron Calorimeter for detection of projectile spectators Measurement of: 1.Centrality: b~ A - N spect ( selection at trigger level) ; 2.Event-by-event fluctuations ( to exclude the participants) ; 3. Reaction plane; 4. Beam intensity ( by detecting the EMD neutrons ).

Schematic view of PSD configuration. Low beam intensity. Detection of fragments. (25 modules) Beam hole Full beam intensity. Minimum 107 modules. spectator spots at Z=15m E au =15 AGeV X Z Optional

Conception of PSD: I.Compensation: ε e / ε h = 1 -- compensated calorimeter. σ(E)/E = a/√E + b ∙ │1- ε e / ε h │ -- constant term equals to zero. II. Lead/Scintillator sandwich: Compensation at Pb:Scint=4:1. For thickness δ Pb =16 mm and δ Scint =4 mm σ E /E ~ 50%/√E. III. Light readout – WLS-fibers to avoid the Cherenkov radiation. IV. Signal readout – Micropixel APD (MAPD) to avoid nuclear counter effect, detection of a few photons signal, compactness, low cost, new technology. V. Longitudinal segmentation – for permanent calibration of scintillators in radiation hard conditions, uniformity of light collection from WLS-fibers. VI. Modular design – transverse uniformity of resolution, flexible geometry, simplicity.

Light readout from scintillators. 6 fiber/MAPD 10 MAPDs/module 60 lead/scintillator sandwiches. groove with WLS-fiber

Properties of selected MAPDs. Type: MW-3d. Size: 3x3 mm 2. Number of pixels: 10 4 /mm 2. Photon detection efficiency:~20%. Gain: 5-6 x10 4. Working voltage: V. Production: Dubna-Mikron. (Z.Sadygov).

Results of beam test of first PSD module prototype GeV, GeV, GeV Summary energy deposition in PSD module for different hadron energies. Geant-MC To check the PSD conception first module prototype was developed and tested in The results are described in internal CBM report. To measure the realistic energy resolution the calorimeter prototype of 9 modules was produced this year. It is ready for beam test.

Some components of PSD module. MAPDs Scintillator tile with groove Electronic board with amp’s and HV divider

PSD module assembling at INR

Construction of supermodule for beam test at CERN.

PSD prototype is installed at NA61 beam line at CERN. Start of beam on Sept., 27.

Future plans. Beam test of 3x3 array of PSD modules. Calibration with muons. Measurement of energy resolution at hadron energy GeV. Study of the LED monitoring system performance. Analysis of the data. Preparation of the paper on PSD performance. Study of long-term stability of readout. Study of new MAPD samples. Construction of larger-scale calorimeter for the measurement of transverse non-uniformity of energy resolution. Final decision on PSD design.

Thank you!