hv divider modifications
Post on 31-Dec-2015
36 Views
Preview:
DESCRIPTION
TRANSCRIPT
HV divider modificationsHV divider modifications
M. Raggi, T. Spadaro, P. Valente
&
G. Corradi, C. Paglia, D. Tagnani
MotivationsMotivations
Ringing & shoulder of the signal…
… and their effects on the time-over-threshold readout
Equivalent resistance Req= 3.36 M
At 1500 V maximum current is Imax=1500 V/ 3.36 M = 446 mA
Dissipated power:
PR= V·I = 107 V × 446 mA = 48 mW on R=240 kPR1= 2V·I = 214 V × 446 mA = 96 mW on R1=2RPtot=V·I = 446 mA × 1500 V = 670 mW total
V0=1500
Req=3.36M
Original dividerOriginal divider
V0=1500 V
Req=2.9M
Vclamp=280 V
Req= 2.9 M
Tension on divider is (1500 –Vclamp)Imax=(1500V-Vclamp)/ 2.9 M= 420 A
PR=VR × I = 100.8 V × 420 42.3 mW on each resistor (-6mW)Pdiodes= Vclamp × I = 280V × 420 = 117 mW ~ 60 mW per diode Ptot=Veq × I = 420 × 1500 V = 630 mW total
First dynode clamp Quenching of d10 d11 d12 and anodeQuenching capacitorsHV decoupling resistor (10 K)
Divider with 1st dynode clampDivider with 1st dynode clamp
• We use– R=240 K, V=voltage from HV supply
• For the totally resistive (original) divider Req=14 R
– G=iVi
=KNVN
– Vi=V/(14R)
• For the divider with diode clamp Req=12 R
– G=K1(V-V0) iVi
=K1(V-V0)KN-1V(N-1)
– Vi=(V-V0)/(12R)
Gain modelGain model
Ratio between gain with resistive divider (old) and first dinode clamp divider (new)
K1 is already saturated, and thus cannot increase the gain. Increasing the tension on first dynode is useless.
Gain ratio can be improved by lowering the clamp voltage
(but only 10% better at 120 V)
Data/MC comparisonData/MC comparison
Final dividerFinal divider
• 200 dividers already mounted
• only 1 with discharges (due to bad cable)
top related