1

HBD update

Itzhak TserruyaDC Upgrades meeting, January 14, 2005

• NIM paper II: Generic R&D ~ completed• Full scale prototype construction• Pending issues towards final design• Electronics status• Monte Carlo

2

HBD NIM paper #2:

Title: A Hadron Blind Detector for the PHENIX Experiment at RHIC.

1. Introduction

2. HBD Concept

3. Set-up and Experimental conditions

4. Detector response as function of the drift field; 4.1 Detector response to mip and alpha particles

4.2 Detector response to photoelectrons

5. CsI Quantun Efficiency

6. Discharge probability and saturation effec 7. Aging studies

8. Summary and Conclusion

Time table- draft under review within the authors- final paper to be posted to phenix-p-l for possible comments within one week.- submit to NIM.

3

Full scale Prototype design

Complete set of engineering drawings available at:https://www.phenix.bnl.gov/phenix/WWW/p/draft/ravini/hbd_drawings/prototype

4

Exploded view

This exploded view corresponds to a slightly older design, but the basic concept remains unchanged:•The prototype has a total of 10 panels and not 11 as in this drawing,•The panels on the active area of the detector are glued to the pad plane made of kapton (50μ thick)

5

Prototype status and goals (I) Construction status: All raw material and components ordered and delivered(Delay on delivery of HV surface mount resistors. Ordered in July 2004. Delivered this week)

All manufactured parts ready(Delay on the delivery of the pad plane. Was shipped from CERN yesterday)

7 out of 10 panels ready Assembly jigs in the shops. Expected delivery 1-2 weeks Mechanical assembly expected to be complete within 4-5 weeks

Goals (once the detector box is completed) Mechanical tolerances Leak tightness Flush with N2 while monitoring H2O and O2

Install large GEM stack Flush and operate with CF4

Ship to BNL Test with prototype electronics

6

Prototype status and goals (II)

Large GEMs The prototype will be equipped with one

set of large GEMs (23 x 24 cm2) 12 large GEMs HV segmented produced

at CERN (8 standard + 4 gold plated) Stretching, mounting and gluing on 5mm

wide frame OK CsI evaporation OK Tested at 104 gain for more than 2

months. OK Pending problem: mesh stretching New set with surface mount HV resistors

will be prepared soon.

7

Pending issues towards final design

Two main issues: Acceptance Detector envelope

Other smaller details: Design new window to allow installation in retracted position

starting at r = 25 cm) Location of gas in/out for window N2 flushing

8

HBD acceptance

acceptance: 4 x 25.5o

acceptance: 6 x 25.5o

or even 8x 25.5o

9

Acceptance, number of channels, pad sizeCentral arm acceptance: φ = 90o , |η| = 0.35 θ = ± 19.7o

Constraint: (4 connectors) 96 pads per detector element

a) Present acceptance: 4 x 25.5o panel length 260 mm 768 pads per arm

Total number of channels: 1536

b) Enlarged acceptance: 6 x 22.5o panel length 227 mm 1152 pads per arm

Total number of channels: 2304

|η| z [mm] θ a [mm] GEM size a [mm] GEM size

0.4 472 22.3 15.7 260 x 236 14.7 227 x 236

0.425 504 23.6 16.2 260 x 251 15.1 227 x 251

0.45 535 25.0 16.7 260 x 267 15.6 227 x 267

= 4 x 25.5o = 6 x 22.5o

Emerging choice

10

Detector envelope

z

80 cm

120 cm

z [mm]• Acceptance || < 0.4 535• Frame width 2x (5+1) 12•Detector covers 2x(3/4” +0.5 mm) 39(w/o head of screws)•Services 2x40 80(prototype has 106 mm) -------- 666

•No problem in r•Very tight in z

Requested HBD envelope: z = 680 mm

All external services, HV, LV and signal cables, gas pipes … , will

be within this envelope

11

Electronics status Analog electronics (BNL Instrumentation): Components for 3000 channels ordered. Few hundred channels will be available soon. Prototype readout board (for a 10x10 cm2) ready for test. Provisions are being made for a second prototype board of almost

final size to be used with the prototype detector.

Excellent shape

Digital electronics (Columbia): Cables and connectors identified Prototype FEM under design Three phases:

- Prototype production 5 m- Prototype test 3 m- Final production 6-9 m

Very good progress, but still the limiting factor in the overall schedule: Trying to see whether we can improve it.

12

HBD Monte Carlo HBD prototype geometry in PISA:

Two arms, 8 detector elements per arm Acceptance: = 100o and || = 0.4 in

each arm +/- magnetic field configuration

HBD pattern recognition and tracking – done, as part of the PHENIX reconstruction software in Fun4All framework.

Whole chain works on WIS local PC-farm with pro.56 library using pisaToDST.C with single particle MC, pure HIJING events, HIJING merged with e+e-

13

Why do we call it HBD?Event display: central HIJING event

14

CB from central HIJING events (b<2fm)Pattern recognition: Remove one pad clusters. Cluster charge > 20 p.e. Match Central Arms electron tracks to HBD with 3s

p-dependent cuts. This matching reduces the number of electrons by a factor of ~3 i.e. the CB by ~10.

Reject “conversions” tracks with amplitude cut (>60 e)

Reject Dalitzes with close hit cut (< 200 mrad)

For m > 200 MeV/c2 the rejection factor is > 100

18K events

15

Signal and BackgroundSignal:

16

Summary and outlook

Still a lot to do but so far so good.

Getting ready for the final detector construction

Internal proposal for the Collaboration under preparation