modeling for mcp-pmt output signal · 2012-01-21 · f.tang 50 modeling for mcp-pmt output signal...
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F.Tang 50
Modeling for MCP-PMT Output Signal1. Modeling with RC Load
• Mathematic modeling
• Spice simulation with linear-rise Impulse force
• Spice simulation with 2-τ exponential force
• Comparison between simulation and test
2. Modeling with RLC Load (and includes T-line)
• Mathematic modeling
• Spice simulation
• Comparison between simulation and test
3. Summary
F.Tang 51
Camden’s Test
60mV420.4ps1.2p1
80mV477.4ps1.5p4
117mV478.0ps2.3p9
145mV480.0ps2.8p16
Vp(test)Tr(test)Capixel
16-pixel 9-pixel
4-pixel
1-pixel
F.Tang 52
Tube and AnodesAnode Pads
elastomer
From Jean-Francois’ calculation:
The tube current source should be linearly rise
in a time interval of 75ps-225ps, which is
related to tube structure and the field
between MCP_out to anode, then suddenly
stops, we call it as “linear-rise impulse”
“linear-rise impulse”
75ps-225ps for different tubes
t
i
SMAs
F.Tang 53
CIf the current source is a impulse, then
rise time of output pulse is a step
function, amplitude is proportional to
1/C, then decay with τ=RC.
Modeling for Tube’s Output with RC Load
Rise Time is Nothing Dependent If
Input is a Impulse Current Source!
Ignore slow current path
F.Tang 54
Effect of C_anode to the Rise Time of Output Signal (1)
Input force: Linear-rise Impulse Current Source (tr=100ps, tf=1ps, Ip=1A)
Outputs by Sweeping C from 1pF to 10pF
with R=infinite
Input Force
F.Tang 55
Effect of C_anode to the Rise Time of Output Signal (2)
Input force: Linear-rise Impulse Current Source (tr=100ps, tf=1ps, Ip=1A)
Output by Sweeping C from
0.1pF to 3.6pF with 0.5pF step
F.Tang 56
Tube’s Rise Time Dependency with Finite Rise Time Exp-type Input
Sweep C from
0.5p -4p
Effect of C_anode to Rise Time of Output Signal (1)
Input force: 2-τ Exponential Current Source (tr=100ps, tf=300ps)
Input force
Outputs by Sweeping C
F.Tang 57
Sweep R from
50-500 ohms
Effect of C_anode to Rise Time of Output Signal (2)
Input force: 2-τ Exponential Current Source (tr=100ps, tf=300ps)
Input force
Outputs by Sweeping R
Tube current should
not work like that!
F.Tang 58
Modeling for Tube’s Output With LRC Load
= 1)( 2 ++
+=
sRCLCsRsLsVa
RsLR
sRCLCsRsLsVo
+•
+++
=1
)( 2
LLedge
C
Ignore slow current path
i=δ(t)
MCPOUT is an AC ground for fast signal
Vo
R
Transfer Function:
Laplace transform with impulse current force:
Fast signal components: 2-Pole!
Va
12 ++=
sRCLCsR
F.Tang 59
MCP-PMT Model with Anode L and C
Swept C from 1pF to 10pF , We
see the rise time of output pulse
is a function of C_anode
C_scope
Pulse shape is very close to our test pulse shape
F.Tang 60
Comparison of Output Pulse Shapes
Simulation Test
16-pixel16-pixel
F.Tang 61
Model with LRC and T-line
Scope InputMCP-PMT
F.Tang 62
Summary
• Model with RLC seemed accurate.
• Output pulse shape from simulation is very consistent to the one we obtained from scope.
• Similar output behaviors have been observed from simulation as Photek obtained from their tests.
• More tunes on both model and shape of current source may be needed for further comprehensive simulations
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