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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 …
