SP08: Constant Fraction Discriminatorveritas/docs/sub_proj8/cfd_update.pdf · SP08: Constant...

SP08: Constant Fraction Discriminator

Jeremy SmithJeter Hall

David KiedaVladimir Vassiliev

August 3­6, 2001 Leeds

Timeline

Simulations completed April 15, 2001CFD board lay out completed May 25, 2001PDR approval June 6, 2001CFD boards manufactured July 10, 2001CFD boards stuffed July 15, 2001Test board prototype completed July 30, 2001Testing begun July 31, 2001

August 3­6, 2001 Leeds

Night Sky Background

m=7.4 is 0.2 pe/nsm=6.6 is 0.4 pe/nsm=5.9 is 0.8 pe/nsm=5.1 is 1.6 pe/nsm=4.4 is 3.2 pe/ns

Stephane’s LeBohec calibration:m=0.0  is  180 pe/ns

August 3­6, 2001 Leeds

Peak trigger rate

VERITASoperation

region

August 3­6, 2001 Leeds

CFD in fADC channel

by Jim Buckley, WBS SP7

0U(t)peN32

)�U(tpeN)32

(1 =⋅⋅+−⋅⋅+−

0U(t)32

)�U(t)32

(1 =⋅+−⋅+−

U(t)�peN(t)�dcUU(t)peN32

)�U(tpeN)32

(1 ⋅++=⋅⋅+−⋅⋅+− noise

Theory Practice

U(t)�peN1

peN

(t)�

peNdcU

U(t)32

)�U(t)32

(1 ⋅++=⋅+−⋅+− noise

August 3­6, 2001 Leeds

CF discriminator time walk

August 3­6, 2001 Leeds

CF discriminator time dispersion

August 3­6, 2001 Leeds

CFD Functional SchematicZero crossing comparator

1.5 ns delay

CFD rate feedback

f2VVariable gain

Time walkoptimization

PMTsignal

Discriminatorthresholdadjustment

Programmable width

Coincidence resolving timeadjustment

fraction

Thresholddiscriminator

D

CLK

Q

R

August 3­6, 2001 Leeds

CFD board schematic

August 3­6, 2001 Leeds

Frequency to voltage feedback

August 3­6, 2001 Leeds

CFD board

August 3­6, 2001 Leeds

CFDs

August 3­6, 2001 Leeds

CFD & fADC

August 3­6, 2001 Leeds

CFD & fADC

August 3­6, 2001 Leeds

CFD Test Board Prototype

August 3­6, 2001 Leeds

CFD & ADR2100

August 3­6, 2001 Leeds

Pulse

August 3­6, 2001 Leeds

Team

August 3­6, 2001 Leeds

Status

Testing …