Saturation study of ROMEO
Index
- Short summary
- Saturation Function
- Scripts, data, and Keywords
- Charge
saturation vs waveform saturation with 10ns single pulse beam
- Charge
saturation vs waveform saturation with 50ns single pulse beam
- Single pulse
beam and continuous beam
- A) 10ns waveform
(1 shot of 10ns beam, identical to the above example)
- B) 50ns waveform with
10ns bin ( continuous 5 shot of 10ns beam)
- Weighted
MCHits, semi-current saturation vs waveform saturation with 50ns beam
- A) 5ns bin, 50ns beam
- B) 10ns bin, 50ns beam
- C) 25ns bin, 50ns beam
- D) 50ns bin, 50ns beam
Short summary
This is studies about saturations in ROMEO, with two different
saturation mode "waveform saturation" and
"semi-current saturation".
The semi-current saturation used to be default mode of ROMEO, while
waveform saturation is used in pmt-simulator.
With 10ns square beam, my result shows considerable underestimate of
output NPE in semi-current saturation, over 500 input NPE / 10ns.
This discrepancy will be smaller if we assume wider waveform over 50ns
(which is more realistic).
On the other hand, the weighted input hits with wide bin-width over
10ns gave opposite results.
Since a weighted hit represents numbers of unweighted-hits within given
time bin-width, the hit has much higher amplitude than the unweighted
case.
Therefore the waveform saturation works much stronger.
With the default setting of hit-constructor, we have 3ns bin weighted
hits in the first ~400ns and then 25ns bin weighted hits for FADC.
The latter wide weighted hits may result in an underestimate of total
NPEs if we apply waveform saturation.
(EHE group is not using waveform saturation currently)
contact person: hoshina(at)icecube.wisc.edu
Saturation Function
The saturation function is obtained by Chris Wendt.
x : input current [mA]
y : output current [mA]
P : 1.0709e-3 (constant)
X0 : 48.965 (constant)
X1 : 129.74 (constant)
1/y = 1/x + P * (ln(1+(x/X0)^3) / ln(1+(x/X1)^0.5))
This is the saturation curve of y / x as a function of input current
[A] (coded in RMOPMTCurrentBasedSaturation.h)
Scripts, data, and Keywords
Keywords :
- Semi-current
saturation
Romeo internally does binning with bin width 2ns (default) at charge
response module.
(to switch off the binning, set 0 to
RMOParameter::RMOOutputTimeResolution.)
Number of mc charge is then less than input MCHits, which helps to save
CPU time at waveform-integration.
Saturation is applied to every binned charge, as a function of average
current:
average_current = charge_in_the_bin / bin-width
- Waveform
saturation
Saturation is applied
directly to the waveform.
This method is used by pmt-simulator.
current = waveform_voltage_at_any_t / 43(ohm)
Charge
saturation vs waveform saturation with 10ns single pulse beam
[script
For the case of 4 and 5, input PEs are merged into one MCHit with
weight of x-axis NPE]
Beam property:
The input photons distributes from t = 100 ns to 110 ns (10ns beam).
Number of photons per beam is shown in x-axis.
For the case of 4 and 5, input PEs
are merged into one MCHit with
weight of x-axis NPE.
- No saturation. [data]
- Waveform saturation only, no
binning. [data]
- semi-current saturation with
charge-bin width 2ns. [data]
- Romeo internal charge
binning + waveform saturation. [data]
Waveform saturation is applied after 2ns charge binning.
- Weighted MCHit(EHE MCHit)
+ semi-current saturation with 10ns charge bin width. [data]
The input is only one MCHit, but is weighted by a factor of 100 ~1000.
No charge binning (since the input is only 1 MCHit) but bin width 10ns
is used to calculate average_current.
- Weighted MCHit + waveform
saturation. [data]
No charge binning. Merged bin-width 10ns is not used to calcurate
saturation.
[top]
Charge
saturation vs waveform saturation with 50ns single pulse beam
Same figure but beam width is extended 50ns.
- No saturation. [data]
- Waveform saturation only, no
binning. [data]
- semi-current saturation with
charge-bin width 2ns. [data]
- Romeo internal charge
binning + waveform saturation. [data]
- 5 Weighted MCHits(EHE
MCHits)
+ semi-current saturation with 10ns charge bin width. [data]
- 5 Weighted MCHits +
waveform
saturation. [data]
[top]
Single pulse
beam and continuous beam
Alex's study suggests that the shape of waveform (gaussian or
rectangular) affects saturation.
In the practical cases, however, waveforms are wider than 10ns
especially at high-PE density.
The semi-current saturation with weighted hits at ~50ns waveform (case B) shows much better
agreement to non-weighted hits with waveform saturation, compared with
the single 10ns waveform pulse (case
A).
A) 10ns waveform
(1 shot of 10ns beam, identical to the above example)
- 10ns beam with no weight, no saturation [data]
- 10ns beam with no weight, waveform
saturation [data]
- A weighted hit with waveform
saturation [data]
- A weighted hit with semi-current
saturation (binwidth 10ns) [data]
Next is the ratio plot of purple
/ red and blue / red.
With the blue line I
tried to reproduce Alex's
fig , however, my result shows smaller deviation from 1.
- Left : SPE waveforms of unweighted hits
- Center: integrated waveform (no saturation) of unweightedfor hits
(BLACK)
- Right: integrated waveform of unweighted hits, waveform
saturation (RED)
- Left : SPE waveform of a weighted hit (no saturation)
- Center : integrated waveform of a weighted hit, waveform
saturation (PURPLE)
- Right : integrated waveform of a weighted hit, semi-current
saturation (BLUE)
[top]
B) 50ns waveform with
10ns bin ( continuous 5 shot of 10ns beam)
- 50ns beam with no weight, no saturation [data]
- 50ns beam with no weight, waveform
saturation [data]
- Five weighted hits with waveform
saturation [data]
- Five weighted hits with
semi-current saturation (binwidth 10ns) [data]
Next is the ratio plot of purple
/ red and blue / red.
With the blue line I
tried to reproduce Alex's
fig (you need to multiply x-axis of next fig by a factor of 5),
however, my result shows much smaller deviation from 1.
Presumably we are using different setup??
- Left : SPE waveforms for unweighted hits
- Center: integrated waveform (no saturation) for unweighted hits
(BLACK)
- Right: integrated waveform of unweighted hits, waveform
saturation (RED)
- Left : SPE waveform of a weighted hits (no saturation)
- Center : integrated waveform of 5 weighted hits, waveform
saturation (PURPLE)
- Right : integrated waveform of 5 weighted hits, semi-current
saturation (BLUE)
[top]
Weighted
MCHits, semi-current saturation vs waveform saturation with 50ns beam
[script]
A) 5ns bin, 50ns beam
- Left : SPE distribution of weighted hits, no saturation (500 PEs
/ weighted hit)
- Center : integrated waveform of 10 weighted hits, waveform
saturation (PURPLE)
- Right : integrated waveform of 10 weighted hits, semi-current
saturation (BLUE)
- 50ns beam with no weight, no saturation [data]
- 50ns beam with no weight, waveform
saturation [data]
- Ten weighted hits with waveform
saturation [data]
- Ten weighted hits with
semi-current saturation (binwidth 5ns) [data]
- Left : weighted hits are injected every 5ns up to 50ns
- Right : Same as left, expanded higher NPE density
[top]
B) 10ns bin, 50ns beam
see also B) 50ns waveform
with
10ns bin ( continuous 5 shot of 10ns beam)
- 50ns beam with no weight, no saturation [data]
- 50ns beam with no weight, waveform
saturation [data]
- Five weighted hits with waveform
saturation [data]
- Five weighted hits with
semi-current saturation (binwidth 10ns) [data]
- weighted hits are injected every 10ns up to 50ns
[top]
C) 25ns bin, 50ns beam
- Left : SPE distribution of weighted hits, no saturation (2500 PEs
/ weighted hit)
- Center : integrated waveform of 2 weighted hits, waveform
saturation (PURPLE)
- Right : integrated waveform of 2 weighted hits, semi-current
saturation (BLUE)
- 50ns beam with no weight, no saturation [data]
- 50ns beam with no weight, waveform
saturation [data]
- Two weighted hits with waveform
saturation [data]
- Two weighted hits with
semi-current saturation (binwidth 25ns) [data]
- weighted hits are injected every 25ns up to 50ns
[top]
D) 50ns bin, 50ns beam
- Left : SPE distribution of weighted hits, no saturation (5000 PEs
/ weighted hit)
- Center : integrated waveform of 1 weighted hits, waveform
saturation (PURPLE)
- Right : integrated waveform of 1 weighted hits, semi-current
saturation (BLUE)
- 50ns beam with no weight, no saturation [data]
- 50ns beam with no weight, waveform
saturation [data]
- Two weighted hits with waveform
saturation [data]
- Two weighted hits with
semi-current saturation (binwidth 25ns) [data]
- weighted hits are injected every 50ns up to 50ns (1 MCHit)
[top]