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. KonczykowskiCEA Saclay06/28/08

Central Detector(Silicon and maybe Micromégas)

Forward Detector

CLAS12 - Spectrometer

Micromegas principleMicromegas principle

~100 ~100 mm

thin gapthin gap

Fast ions collectionFast ions collection

ComparisonComparison

4 x 2MM

4 x 2SI

2 x 2SI + 3 x 2MM Specs.

pT/pT (%) 2.9 2.1 1.6 5

(mrad) 1.3 15.1 1.4 <10-20

(mrad) 10.9 2.9 2.6 <10

z (μm) 212 1522 267 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 V1500 V2000 V2500 V3000 V

Simulations in B-fieldSimulations in B-field

Regular electric field configuration :

Large Lorentz angle (~ 75o)

- 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 V3Bulk MM detector equipped with Gassiplex Board (96 channels)

Active area 30x30 mm2, pitch 300 μm2.25mm Drift-Mesh, 128µm Mesh-StripsGas: 5% iC4H10 + 95% Ar

UV Laser

Drift electrode

Al-mylar

Micromesh

Strips

~400V

Con

vers

ion

1.88

mm

Am

plifi

catio

n

128μ

m

~1kV/cm

~40kV/cm

Experimental principle

Focusing lens

Filter

~800V

e-

Ar-iC4H10

UV Laser

Drift electrode

Micromesh

96 Strips

~400V

Con

vers

ion

1.88

mm

Am

plifi

catio

n

128μ

m

~1kV/cm

~40kV/cm

With a magnetic field

Focusing lens

Filter

~800V

B

e-

ΘLorentz

This distance is related to lorentz

Ar-iC4H10

Data acquisition & analysis

•<ADCi/ΣjADC>

•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

σ²exp=(σ2laser+σ²det)/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 longMaterial: 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 mmTile 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 m²Dead zone between detectors not optimized on the prototype !!!

Y cylinder

X tileSupport structure

Micromegas Bulk Demonstrator

Y cylinderX tile

Y connector

Y HT cable

Y joint

Interface attachment to handcart

Length: 600 mmDiameter: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 views During 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)

55Fe 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)

ADC55Fe shaped signal

Signal - noise

Noise

Channel 71

512 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 test @ 5T with DVCS magnet.

400 mm

Prototype « cart »

View with interface

Electronics box

detector

HT filter

Gas distribution

DVCS magnetTelescopic slide rail

Prototype inside CLAS+DVCS magnet

Goals:•Dry test for test beam end 2008: full prototype on handcart•Lorentz angle @ 5T: one X tile with UV laser •Cosmic test @ 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:

2007 08 09 10 11 12 13 2014

Feasability Definition Development Production Experiment

A B C D EProject

Decision(Si and/or MM)

Milestones

PreliminaryDesignReview

ProductionReadiness

Review

2k-ch.v1

Prototyping ForwardB

FinalDesignReview

now

08 09

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 is2. can we reach a satisfactory voltage setup with athin cylindrical Micromegas detector.

Why we need tests in B-fieldWhy we need tests in B-field

Space resolution

Electronics schematicAMPLIFIER

ORTEC

454

QUAD DISCRIM.

LECROY

821

DUAL TIMER

N93B

50ns

SEQUENCER

V551

LEVEL

ADAPTER

8010

DUAL TIMER

N93B

50ns

IN

IN1

OUT START

OUT

OUTMESH (IN)

GATE GEN.

VETO

START

TRIGGER

E.MARKER

OUT2

BUSY

CLR CLK

IN2

GASSIPLEX

IN

CLR OUT1

STRIPS (IN)

C-RAM

V550 CLK

T/H

OUT

START

OUT

STRIPS DATA (OUT)

CLEAR

DREADY

CONV

VME

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

Palette

DE/E

19.8% PLV1-4 23/04/2008

20.2% 2.07E-01 2.33E-01 2.02E-01 2.10E-01 2.12E-01

20.6% 2.12E-01 2.34E-01 2.15E-01 2.08E-01 2.13E-01

21.0% 2.07E-01 2.20E-01 2.01E-01 1.98E-01 2.01E-01

21.4%

21.8% Vd=520V

22.2% Vg=420V ig=27nA

22.6% d-gaz=2l/h

23.0%

23.4%

1.1% sigma

15% Delta max

Long Prototype study with 55Fe

Energy resolution

Homogeneity of the detector

Noise study: preliminary resultsPedestal 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 ~6for 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 2Mesh

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)

Mask2 à 4 mm 50 à 100 m

Plots: 200 à 400 microns

Mini: 4 mm

Concept du bulkConcept du bulk