Download - Forward TOF Prototyping

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Forward TOF Prototyping

Ryan Mitchell

GlueX Collaboration Meeting

November 2005

Purpose of the Forward TOF

• Particle ID:

– π/K separation up to 1.8 GeV/c.

• Level-1 Trigger:

– Fast forward charged track count.

• Calorimetry:

– Tag hadronic showers in the forward calorimeter.

Forward TOF

Particle ID:

70 ps time resolution

1% momentum and length resolutions

Current Design(and possible improvements)

(Not to Scale)42 bars

Scintillators: 252 ×6 × 1.25cm Eljen-200 or Bicron

Beam Hole: 12 × 12 cm Hole

Photomultiplier Tubes: XP2020

Electronics: Alberta CFD JLab F1TDC fADC

Would thicker bebetter?

Is this the best we can do for...

timing?fringe field?

Need more experiencewith this (esp. range)...

Outline of Prototyping I:Finished/Ongoing

1. IHEP Test Beams – 2001 to present

-- < 80ps resolution is achievable with 200 × 6 × 1.25cm bars

-- December 2005 tests will look at 250cm bars

• IU Cosmic Ray Tests – Spring 2004

-- First measurements were made with a 250 × 6 × 1.25cm bar

-- Find 88ps resolution in the center region (2 bars)

• TRIUMF Beam Test – Summer/Fall 2005

-- Low energy π/μ/e beam used on two layers of scintillators

-- Probing time resolution for a variety of dE/dx and all positions

-- Discriminator performances

Outline of Prototyping II:3 Year Plan

1. IU Cosmic Ray Tests – 2006 to Spring 2007

-- Another round of tests with the IU cosmic ray stand.

-- 88ps is not sufficient; look at bar thickness.

-- Try a variety of phototubes.

-- Use Alberta CFD and commercial CFD and LED.

2. Hall-B Electron/Photon Tests (with LGD) – Fall 2007 Run

-- Take the final design to the Hall-B alcove test

-- Scan 2 walls of 10 bars each (one full length; one half length).

-- Correlate with the LGD and tagger.

3. Magnetic Field Tests (with LGD) – 2008

-- Make sure everything works in the fringe field.

2004 IU Cosmic Rays Summary

PMT: XP2020TDC: LeCroy 2228A (50ps least count)ADC: LeCroy 2249A and IU fADCCFD: Ortec and University of AlbertaScint: 250 × 6 × 1.25cm

Three movable cosmic ray telescopes in a logical OR.Scintillator is enclosed in a light-tight box (the “coffin”).

2004 IU Cosmic Rays Summary

Attenuation Length = 160.5 ± 4.2 cm

Velocity = 14.77 ± 0.09 cm/ns

Time Resolution = 88 ps

2005 TRIUMF Test Beam Summary

First two weeks of June 2005.

120 and 250 MeV/c π/μ/e beams.

Full size and half size scintillators.

Same electronics as cosmic ray tests:PMT: XP2020TDC: LeCroy 2228A (50ps least count)ADC: LeCroy 2249A and IU fADCCFD: Ortec and University of AlbertaScint: 250 × 6 × 1.25cm

2005 TRIUMF Test Beam Summary

2005 TRIUMF Test Beam Summary

Sample ADC and TDC from one bar end.

-- 120 MeV/c π/μ/e beam -- 3 Moyal distribution fit to ADC -- 3 Gaussian distribution fit to TDC

e+ e+

μ+μ+

π+π+

2005 TRIUMF Test Beam Summary

Four scans along a front bar.

Mean ADC from the two bar ends are superimposed.

Attenuation Length = 136.7 ± 3.4 cm

pionmuonelectron

2005 TRIUMF Test Beam Summary

Anomalies in ADC vs TDC

Good

μ+

π+

Severetime-walkfor electron

e+e+ e+

μ+

μ+ μ+π+

π+ π+

Double-peakelectron

Double-peakmuon

-- Similar behavior for both Alberta and Ortec CFD.-- Needs further analysis.-- Need more tests with different discriminators.

2005 TRIUMF Test Beam Summary

π/e separation

μ/e separation

π/μ separation

Four scans along a front bar.

TDC differences from the two ends are superimposed.

Very consistent run to run results.

Nonlinearities are likely due toADC vs TDC anomalies.

Very Important. Needs to beinvestigated further.

Three Outstanding Design Issues

1. The 88ps resolution for the 252 × 6 × 1.25cm bars is not acceptable. Try doubling the bar thickness.

2. Understand the discriminator issues. Try out a few commercial models (CFD and LED).

3. Explore different phototube options. Can we find something better than the XP2020 for timing and performance in a magnetic field?

Phase I Prototype (2006): Cosmics

PLAN:Use the existing IU cosmic ray test stand to explore: -- bar thickness -- discriminators -- phototubes

BUDGET:Phototubes: 12k (e.g. Hamamatsu R9779, Hamamatsu R2083, Hamamatsu R1828, Electron D744, Photek PMT340)Discriminators: 12k (e.g. Ortec 935, Phillips 7106, 708, 710, 715, 730)

2006 Request = 24k

Phase II Prototype (2007): Test Beam

PLAN:Test 2 walls of 10 scintillators each (one long horizontal wall and one short vertical wall) in November 2007 along with the LGD. -- use electrons and photons from Hall-B -- scan bars for time and position resolutions. -- correlate the timing with the LGD and the tagger.

BUDGET:Phototubes: 18k (instrument 20 bars with XP2020)Scintillators: 5kHigh Voltage: 25kCables: 5kSupplies: 6k

2007 Request = 59k