TOF Monitor System Status

F. HarrisU. of Hawaii

June 13, 2006

BESIII TOFCrucial for particle ID• Barrel

– Two layers, 88 counters each layer.– 50mm x 60mm x 2500 mm (inner layer).– Radius from 810 to 930 mm.– BC408

• Endcap– 88 fan shaped pieces – each end.– BC404

• Time resolution 1-layer (intrinsic):– Belle: 70 to 80 ps – Beam tests: < 90 ps– Simulation: < 90 ps

• K/ separation2 separation up to 0.9 GeV/c

TOF – IHEPTOF electronics - USTC

TOF Calibration System• Hawaii is building a TOF calibration system for BESIII.

(Fred Harris, Lucas Nguyen, Steve Olsen, Marc Rosen, and Gary Varner)

• Built such systems for both BESII and Belle. • Proposal approved in March 2006.• Important as system monitor and for calibration.

BESII system:

• Replace N2-dye laser with Laser Diode (405 or 440 nm)?– Simpler to use and

maintain.– Longer lifetime.– ~5 x 107 photons/pulse.– Peak power at low rep.

rate:• 405B -- 0.3 W• 405M – 0.6 W (new)

BESIII TOF Calibration System

PicoQuant GmbH LDH-P

Dark box

ADC

for LD

LD driver

TDC

...

CLK

Gate.G.

NIM TTL

attn.

Gate.G. NIM

TTL

attn.

start

gate

in

stop

Ref. PMT (ADC check)

diffuser fiber

bundle

LD

Ushiwaka Magnet Dark

boxfor R5924-70

Will it work?U. Tokyo Measurement System

Generation of Laser Pulse

NIM TTL

CLK

Gate.G.

NIM TTL

attn.

Gate.G.

attn.

LD driver

～ 1.8V(max.)

Trigger pulse

～ 10ns

LD

for LD

threshold

～ 1μs

Bias pulse

～550mV

～400mV

Laser Pulse!!

When we provide bias pulse and triggerpulse , LD generates intensive

pulse !

Uses non-standard pulsingsystem. Safe for BESIII?

Choice of Laser

• LD has many advantages; but is light sufficient with standard pulser?

• N2/dye laser has plenty of light and is considerably cheaper.

• Tentatively choose N2/dye laser initially. LD may be an upgrade.

• Measure efficiency of U. of Tokyo system to determine if LD with standard pulsing has enough light. Gary Varner.

TOF Monitor System

TOF endcap 48 fibers

TOF endcap 48 fibersLaser Light splitter

TOF barrelPMT PMT

PMT

TDC startADC gate

Fiber

TOF barrel 176 fibers

TOF barrel 176 fibers

Electronic switch

fiber

Fiber bundles

fiber

connector Wrapped with steel tube

Use mirror to steer beam – like BESII. Purchase fiber cable bundles (2 cables).

Use Spiricon Beam Analyzer to analyze beam and design optics – laser into fiber bundle.

Optimum design?

BESIII TOF Calibration System

• Many companies interested:– Ogmentum Inc., Sales and Marketing for FiberLabs– CeramOptec– Romack– Fibertech-optica– Fiberguide Industries

• Many choices: (tentative)– Fiber size (100 micron core).– Connectors (FC/PC).– Single fiber jacketing (PVC furcation).– Outer jacketing (SSTL stripwound).– Multiconnector type.– Ferrule.

Fiber Bundle Cables

8.7 m

248 fibers (cores + cladding only)with ferrule on end

2-96 fiber bundles

2 - 28 fiber bundles(24 + 4 spares)

96 fibers with connectors(88 + 8 spares)

106 (18 spares) cables 7.5 m long withconnector on one end and ferrule on other.

Distribution boxes – one side clamps bundle cable;Other side has single feed through connectors

30 (6 spares) cables 2.0 m long withconnector on one end and ferrule on other.

5.4 m

Distribution boxes – one side: multi connectorOther: single connectors (box 40 mm thick max)

9 m

Total length= 21.6 m

Total length= 19.7 m

Cable Dimensions (May 2, 2006)

Fiber Bundle Cables (need 2)Barrel TOF

EC TOF

Fiber Connection to TOF

Cable Routing?

Have plan; need to check cable dimensions carefully

Test Setup at UH• Need TOF counter and

readout for testing TOF laser calibration system.

• Have Belle BC408 TOF counter and 2 BES fine mesh phototubes.

• Use cosmic ray telescope.• Have Caen VME TDC with

computer to readout.• Caen VME QDC ordered.• Will use BESIII readout

when ready.

TBTop counter

Bottom counter

Delay boxes

50 mv, 28 ns out

PS755scalers

TOFPMT

T

B

Test Setup

N S

S

40 mv, 30 ns out

TBS

PS711

4 ns

HV S = 1200 VHV N = 1150 VHV T = 1400 VHV B = 1450 V~2 counts/min

TDC trigger

Test Setup – first resultsTelescope near middle of

TOF

N – B timeσ = 0.87 ns

S – B timeσ = 0.81 ns

N – S timeσ = 0.61 ns

No time walk correction. Need to understand resolution.

Much to do• Complete test setup.• Measure power out and pulse width of UT laser

diode. Will laser diode work for us?

• Decide on laser. Order by end of summer.• Finalize cable design, connectors, etc. Get

quotes. - Order by end of summer.• Install N laser, fiber cables in UH test setup. Test

and finalize design. – Summer 2006.• Test cable in Hawaii. Oct/Nov 2006.• Ship everything to IHEP – Dec. 2006.• Begin installation – Jan. 07

Thanks

Light Source◆ Violet Laser Diode (LD)

Wave Length : 408nm

Violet LD Unit

LD driver

LD head

wavelength (nm)

rela

tive

ou

tput

Typical Spectrum (by Nichia)

LD Intensity Distribution

x (mm)

Npe

the diameter of the bundle

Cable

• CeramOptec (Kevin Bakhshpour):– Fiber: step index MM

• P/N UV90/100/107P (P-polyimide) (~20 – 25 K$/cable)

• P/N UV200/210/235P (~25 – 30 K$/cable)

– 6 – 8 weeks

• Romack (Peter Gordon):– Fiber: step index

• 100 micron ($1.5/m)

• 50 micron ($2.5.m); graded index ($0.5)

– PVC Furcation tubing for single fiber cables– FC/PC connectors– jacketing?

Cable

• Fibertech-optica (Rafal Pawluczyk)– Fiber

• AS100/110UVPI ($0.9/m -> $9900 for fibers)• AS200/220UVPI ($1.35/m -> $14,850 )• 65.2/125 ($0.13/m -> $1430)

• Fiberguide Industries (Tom Christie)– Fiber

• SFS100/110• SFS200/220 (50% more)• AGI6.25/125T (13% more than SFS100)

• Fiber Labs (Jake Weise)– Fiber:

• 190 micron ($7K)• 100 micron (11K)• 62.5 micron ($14K)

Poor efficiency