Central tracker for 12GeV upgrade in HallB Micromégas : a new detector for CLAS12 Detector’s principle GARFIELD simulation Spatial resolution measurement Long Micromégas prototype tests Integration to the CLAS magnet Saclay team: S. Aune, J. Ball, M. Combet, M. El Yakoubi, P. Konczykowski, C. Lacombe-Hamdoun, S. Procureur, F. Sabatié P. Konczykowski CEA Saclay 06/28/08

Central Detector (Silicon and maybe Micromégas) Forward Detector CLAS12 - Spectrometer

Micromegas principle ~100  m thin gap Fast ions collection

Comparison 4 x 2MM 4 x 2SI 2 x 2SI + 3 x 2MM Specs.  pT /p T (%)   (mrad) <10-20   (mrad) <10  z (μm) tbd. (for 0.6 GeV/c,  = 90°)  A mixed solution combines the SI and MM advantages!  The « only SI » solution is never optimal… : less material on the particle path, flexibility, cheap  : feasibility with a 5T field, worst intrinsic resolution Micromégas advantages: Central tracker

1000 V 1500 V2000 V2500 V3000 V Simulations in B-field Regular electric field configuration : Large Lorentz angle (~ 75 o ) - higher drift field - reduce conversion gap 1 mm!  GARFIELD code (CERN)

Experimental setup Magnet refurbishing: Fall 2007 Tests started: February 2008 Magnetic field : 0 to 1.5 T Laser: UV 355nm + neutral filters <50µJ/pulse, 2ns pulse, very good beam size and divergence Detector: MM prototype V3 Bulk MM detector equipped with Gassiplex Board (96 channels) Active area 30x30 mm 2, pitch 300 μm 2.25mm Drift-Mesh, 128µm Mesh-Strips Gas: 5% iC4H % Ar

UV Laser Drift electrode Al-mylar Micromesh Strips ~400V Conversion 1.88mm Amplification 128μm ~1kV/cm ~40kV/cm Experimental principle Focusing lens Filter ~800V e- Ar-iC4H10

UV Laser Drift electrode Micromesh 96 Strips ~400V Conversion 1.88mm Amplification 128μm ~1kV/cm ~40kV/cm With a magnetic field Focusing lens Filter ~800V B e- Θ Lorentz This distance is related to  lorentz Ar-iC4H10

Data acquisition & analysis Lorentz angle mesured from the deviation of the B=0T peak Drift distance: 1.88mm The signal spreads out with the Lorentz deviation → increase the resolution B = 0T B = 1.5T Labview DAQ

Lorentz angle behaviour with the magnetic field

Lorentz angle behaviour with the drift HV this difference may be related to the uncertainty on the drift gap

Spatial resolution Sigma of the average position calculated event by event σ² exp =(σ 2 laser+ σ² det )/N When the magnetic field increases → the resolution increases Test the detector homogeneity B = 0T B = 1.5T

Micromégas prototype for the central tracker

One type of Bulk: Active area; 115 mm for 288 strips, 500 mm long Material: 100 µm PCB, 5 µm Cu, 18µm mesh, 20µm Mylar Two type of structure, X and Y, for Bulk integration: Cylindrical for Y:  ext: 220 mm Tile for X:  int 180 mm One support for up to 3 X tiles and 3 Y cylinders: Channels: 1728 read by AFTER ASIC (T2K) Active area: 0.34 m² Dead zone between detectors not optimized on the prototype !!! Y cylinder X tile Support structure Micromegas Bulk Demonstrator

Y cylinder X tile Y connector Y HT cable Y joint Interface attachment to handcart Length: 600 mm Diameter: 180 / 220 mm Magnet interface (3 Teflon pads) Cylindrical prototype Cylindrical Prototype

Received friday May 23rd

Bulk made at CERN 4*72 strips 4 prototypes have been fabricated and flat-tested, cylindrical test on the way Detailed viewsDuring Bulk realization Long Prototype : fabrication (Jan.-March. 2008)

Flex PCB cable tests :  Strip cables (40cm, 80cm et 80cm U-shaped)  Wire cables (40 cm, 80cm et 80 cm U-shaped) 55 Fe source tests Flex PCB cable, 80 cm U-shaped Acquisition made with T2K Labview DAQ Software Detector’s electronic (FEC +FEM) PLV4: Long Prototype V4 Long MM experimental setup

AFTER signal on the strips Signal Time (x 50 ns) ADC 55 Fe shaped signal Signal - noise Noise Channel time samples

Integration to the CLAS magnet

Out In The prototype will be fixed on a mobile cart (telescopic slide rail) itself fixed on the magnet. The handcart allows full test in and out without dismounting the detector. Will be used for future 5T with DVCS magnet. 400 mm Prototype « cart »

View with interface Electronics box detector HT filter Gas distribution DVCS magnet Telescopic slide rail Prototype inside CLAS+DVCS magnet

Goals: Dry test for test beam end 2008: full prototype on handcart Lorentz 5T: one X tile with UV laser Cosmic 5T: Three X tiles. Goals: Beam test: full cylindrical prototype on cart Beam test: Forward prototype if possible 2000-channel tests #1 and 2 1. During fall 2008, 5T test inside DVCS solenoid: 2. During change-out between e1-dvcs and eg1-dvcs(?), beam test:

FeasabilityDefinitionDevelopmentProductionExperiment ABCDE Project Decision (Si and/or MM) Milestones Preliminary Design Review Production Readiness Review 2k-ch. v1 PrototypingForwardB Final Design Review now 0809 Beam test5T test1.5T test now Conclusion & Perspectives  B-field tests at 1.5T almost done: optimistic results  6 MM detectors to be built at CERN this summer and integrated in the mechanical structure  The whole structure with mounted detectors will be shipped to JLab end of August/beginning of September

ANNEXES

But we need to check: 1. how realistic GARFIELD simulation is 2. can we reach a satisfactory voltage setup with a thin cylindrical Micromegas detector. Why we need tests in B-field Space resolution

Electronics schematic AMPLIFIER ORTEC 454 QUAD DISCRIM. LECROY 821 DUAL TIMER N93B 50ns SEQUENCER V551 LEVEL ADAPTER 8010 DUAL TIMER N93B 50ns IN IN1 OUTSTART OUT MESH (IN) GATE GEN. VETO START TRIGGER E.MARKER OUT2 BUSY CLRCLK IN2 GASSIPLEX IN CLR OUT1 STRIPS (IN) C-RAM V550 CLK T/H OUT START OUT STRIPS DATA (OUT) CLEAR DREADY CONV VME

Data acquisition (Labview)

Data analysis : GUI ROOT Reads the Labview files Substracts the pedestals Draws the average ADC per channel, the position weighted by the ADC value, its evolution during the run, the ADC spectrum for one channel and for all the channels, etc Single Event Viewer

Long Prototype study with 55 Fe Energy resolution Homogeneity of the detector

Noise study: preliminary results Pedestal for channel 71

Summary (preliminary) 0- Electro. Only 1- FEC + Det 2- Flex PCB cable 40 with Strips 3- Flex PCB cable 40 with wires 4- Flex PCB cable 80U with Strips 5- Flex PCB cable 80U with Wires 6- Flex PCB cable 40 x 2 7- Flex PCB cable 2 m Probably not real Without noise optimization: noise with 80cm flex cable ~6 for MIP signal expected ~50. => Flex PCB cables up to 80cm are definitely useable !

-Improved precision tests thanks to a larger drift gap -Direct measurement of gap with the laser setup -Precise variation of the laser intensity with neutral filter wheel -Tests planned in the fall ’08 with e1-dvcs magnet at 5T and large-area detectors Future plans with B-field tests (June- July + fall ’08)

PCB Photoresist 1 Photoresist 2 Mesh UV 1) PCB (pistes, pixels,…) 2) Photoresist 1 (50 à 150 microns ) 3) Grille (inox tissé de 19 microns, 500 LPI) 4) Photoresist 2 (50 à 100 microns) 5) Insolation UV 6) Développement 7) Cuisson (UV et four) Mask 2 à 4 mm 50 à 100  m Plots:  200 à 400 microns Mini: 4 mm Concept du bulk