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Bug #22559

Charge/Light yield incorrect for low energy Ions.

Added by Jason Stock about 1 month ago. Updated 10 days ago.

Status:
Under Discussion
Priority:
High
Assignee:
-
Category:
Simulation
Target version:
-
Start date:
05/08/2019
Due date:
% Done:

100%

Estimated time:
Spent time:
Occurs In:
Experiment:
-
Co-Assignees:
Duration:

Description

This bug has major impact on DUNE's low energy simulations including the radiological model and calibration simulations.

ISCalculatorSeparate is providing highly suspect results for low energy alphas tested from both the singles gun and RadioGen. The results from the G4 simulation look correct qua step sizes and energy deposits, but the resulting VisibleEnergyDepositionAtStep
`207 fVisibleEnergyDeposition = fEMSaturation->VisibleEnergyDepositionAtAStep(step);`
and the resulting number of ionization electrons
`127 fNumIonElectrons = fGeVToElectrons * 1.e-3 * fEnergyDeposit * recomb;`
both appear to be significantly off. A couple test cases are documented below from tests with low energy alphas and protons. For ionization it looks like the correction breaks down for extremely short step sizes causing the suppression factor to be far too aggressive. In fEMSaturation we are not sure what the cause of the excessive suppression is. In both cases the result appears to be off by over a factor of 10 for low energy alphas.

Example:
Alpha:
fGeVToElectrons * 10^-3 * fEnergyDeposit * recomb
42370000×(10^−3)×1.7306995156774208×0.019394845822116223
Proton:
42370000×(10^−3)×1.295708826267528×0.096017041102605741

Alpha:
p fNumScintPhotons$25 = 30.83150501549115
p fScintYieldFactor$26 = 1
p scintYield$27 = 1200
p fVisibleEnergyDeposition$28 = 0.025692920846242626
2 100 3e+03 750 2.12 1.73 0.018 0.0394 volTPCActiveInner_PV ionIoni

Proton:
p fNumScintPhotons$73 = 161.12999583563152
p fScintYieldFactor$74 = 1
p scintYield$75 = 1200
p fVisibleEnergyDeposition$76 = 0.13427499652969294
4 100 3e+03 750 1.68 1.3 0.103 0.413 volTPCActiveInner_PV hIoni

bethe.png (14.4 KB) bethe.png Hans-Joachim Wenzel, 05/09/2019 05:09 PM
alpha.png (4.87 KB) alpha.png Hans-Joachim Wenzel, 05/10/2019 03:37 PM
proton.png (4.81 KB) proton.png Hans-Joachim Wenzel, 05/10/2019 03:37 PM

History

#1 Updated by Lynn Garren about 1 month ago

  • Status changed from New to Feedback

Jason, we find nothing named ISCalculatorSeparate in larsoft or experiment code. Would you please tell us how to find and reproduce the problem?

#2 Updated by Gianluca Petrillo about 1 month ago

Lynn Garren wrote:

Jason, we find nothing named ISCalculatorSeparate in larsoft or experiment code. Would you please tell us how to find and reproduce the problem?

It's larsim:source:larsim/LArG4/ISCalculationSeparate.cxx , in LArSim.
But still an event and configuration to study the issue would help.

#3 Updated by Jason Stock about 1 month ago

Gen fcl files for the singles gun to fire alphas and protons of appropriate energies are provided below. This is done within the framework of `dunetpc`.

Alpha fcl file
```
#include "prodsingle_common_dunefd.fcl"

process_name: SinglesGen

outputs.out1.fileName: "prod_alpha.root"

services.Geometry: @local::dune10kt_1x2x6_geo
source.firstRun: 20000012

physics.producers.generator.PDG: [ 1000020040 ] # alpha
physics.producers.generator.PosDist: 0 # Flat position dist.
physics.producers.generator.X0: [ 10.0 ]
physics.producers.generator.Y0: [ 300.0 ]
physics.producers.generator.Z0: [ 75.0 ]
physics.producers.generator.T0: [ 0.0 ]
physics.producers.generator.SigmaX: [ 0 ]
physics.producers.generator.SigmaY: [ 0 ]
physics.producers.generator.SigmaZ: [ 0 ]
physics.producers.generator.SigmaT: [ 0.0 ]
physics.producers.generator.PDist: 0
physics.producers.generator.P0: [ 0.202368922 ] #T=0.00548952
physics.producers.generator.SigmaP: [ 0. ]
physics.producers.generator.AngleDist: 0
physics.producers.generator.Theta0XZ: [ 1. ]
physics.producers.generator.Theta0YZ: [ 1. ]
physics.producers.generator.SigmaThetaXZ: [ 0. ]
physics.producers.generator.SigmaThetaYZ: [ 0. ]

```

Proton fcl file
```
#include "prodsingle_common_dunefd.fcl"

process_name: SinglesGen

outputs.out1.fileName: "prod_proton.root"

services.Geometry: @local::dune10kt_1x2x6_geo
source.firstRun: 20000012

physics.producers.generator.PDG: [ 2212 ]
physics.producers.generator.PosDist: 0
physics.producers.generator.X0: [ 10.0 ]
physics.producers.generator.Y0: [ 300.0 ]
physics.producers.generator.Z0: [ 75.0 ]
physics.producers.generator.T0: [ 0.0 ]
physics.producers.generator.SigmaX: [ 0 ]
physics.producers.generator.SigmaY: [ 0 ]
physics.producers.generator.SigmaZ: [ 0 ]
physics.producers.generator.SigmaT: [ 0.0 ]
physics.producers.generator.PDist: 0
physics.producers.generator.P0: [ 0.101643685 ]
physics.producers.generator.SigmaP: [ 0. ]
physics.producers.generator.AngleDist: 0
physics.producers.generator.Theta0XZ: [ 1. ]
physics.producers.generator.Theta0YZ: [ 1. ]
physics.producers.generator.SigmaThetaXZ: [ 0. ]
physics.producers.generator.SigmaThetaYZ: [ 0. ]

```

For the LArG4 stage use
```
supernova_g4_dune10kt_1x2x6.fcl
```

#4 Updated by Hans-Joachim Wenzel about 1 month ago

Hi

I would recommend to print out the values of fScintYieldFactor, fVisibleEnergyDeposition and Birks coefficient fEMSaturation->DumpBirksCoefficients(). Then we can see if this values make any sense (e.g. I don't think Geant4 is provided the correct Birks coefficient).

#5 Updated by Jason Stock about 1 month ago

Relevant information (requested by Hans) from an e-mail chain where Steve Gardiner and myself started trying to isolate the issue. The formatting doesn't copy well, and may take me a minute to format correctly.

**********FULL DUMPS****************

Alphas:

    Step#    X(mm)    Y(mm)    Z(mm) KinE(MeV)  dE(MeV) StepLeng TrackLeng  NextVolume ProcName
        0      100    3e+03      750      5.49        0        0         0 volTPCActiveInner_PV initStep
    p fNumIonElectrons$13 = 1624.9864933973804
    p fGeVToElectrons$14 = 42370000
    p fEnergyDeposit$15 = 1.6417553591626004
    p recomb$16 = 0.023360538454039747

    p fNumScintPhotons$17 = 36.520435706297761
    p fScintYieldFactor$18 = 1
    p scintYield$19 = 1200
    p fVisibleEnergyDeposition$20 = 0.030433696421914801

        1      100    3e+03      750      3.85     1.64   0.0214    0.0214 volTPCActiveInner_PV ionIoni
    p fNumIonElectrons$21 = 1422.2189719812022
    p fGeVToElectrons$22 = 42370000
    p fEnergyDeposit$23 = 1.7306995156774208
    p recomb$24 = 0.019394845822116223

    p fNumScintPhotons$25 = 30.83150501549115
    p fScintYieldFactor$26 = 1
    p scintYield$27 = 1200
    p fVisibleEnergyDeposition$28 = 0.025692920846242626

        2      100    3e+03      750      2.12     1.73    0.018    0.0394 volTPCActiveInner_PV ionIoni
    p fNumIonElectrons$29 = 1061.9552473850915
    p fGeVToElectrons$30 = 42370000
    p fEnergyDeposit$31 = 2.0016620550766056
    p recomb$32 = 0.012521518363400846

    p fNumScintPhotons$33 = 21.203890386938447
    p fScintYieldFactor$34 = 1
    p scintYield$35 = 1200
    p fVisibleEnergyDeposition$36 = 0.017669908655782038

        3      100    3e+03      750     0.115        2   0.0123    0.0517 volTPCActiveInner_PV ionIoni
    p fNumIonElectrons$37 = 146.20943100514739
    p fGeVToElectrons$38 = 42370000
    p fEnergyDeposit$39 = 0.11540342175004348
    p recomb$40 = 0.029901862286604592

    p fNumScintPhotons$41 = 3.7779726986963302
    p fScintYieldFactor$42 = 1
    p scintYield$43 = 1200
    p fVisibleEnergyDeposition$44 = 0.0031483105822469417

        4      100    3e+03      750         0    0.115  0.00223    0.0539 volTPCActiveInner_PV ionIoni
        5      100    3e+03      750         0        0        0    0.0539 volTPCActiveInner_PV FastScintillation

    *********************************************************************************************************
    * G4Track Information:   Particle = alpha,   Track ID = 1,   Parent ID = 0
    *********************************************************************************************************

    Step#    X(mm)    Y(mm)    Z(mm) KinE(MeV)  dE(MeV) StepLeng TrackLeng  NextVolume ProcName
        0      100    3e+03      750      5.49        0        0         0 volTPCActiveInner_PV initStep
    p fNumIonElectrons$45 = 1644.1775667839827
    p fGeVToElectrons$46 = 42370000
    p fEnergyDeposit$47 = 1.7514012805364554
    p recomb$48 = 0.022156675207985733

    p fNumScintPhotons$49 = 36.563093714066653
    p fScintYieldFactor$50 = 1
    p scintYield$51 = 1200
    p fVisibleEnergyDeposition$52 = 0.030469244761722209

        1      100    3e+03      750      3.74     1.75   0.0214    0.0214 volTPCActiveInner_PV ionIoni
    p fNumIonElectrons$53 = 1421.697107123746
    p fGeVToElectrons$54 = 42370000
    p fEnergyDeposit$55 = 1.8501788237547563
    p recomb$56 = 0.018135724499698861

    p fNumScintPhotons$57 = 30.423381673137452
    p fScintYieldFactor$58 = 1
    p scintYield$59 = 1200
    p fVisibleEnergyDeposition$60 = 0.025352818060947878

        2      100    3e+03      750      1.89     1.85   0.0177    0.0391 volTPCActiveInner_PV ionIoni
    p fNumIonElectrons$61 = 930.7855185581634
    p fGeVToElectrons$62 = 42370000
    p fEnergyDeposit$63 = 1.5717525549576699
    p recomb$64 = 0.013976775157680374

    p fNumScintPhotons$65 = 18.999181353598836
    p fScintYieldFactor$66 = 1
    p scintYield$67 = 1200
    p fVisibleEnergyDeposition$68 = 0.015832651127999031

        3      100    3e+03      750     0.316     1.57    0.011    0.0502 volTPCActiveInner_PV ionIoni
    p fNumIonElectrons$69 = 259.19001285548597
    p fGeVToElectrons$70 = 42370000
    p fEnergyDeposit$71 = 0.31618769241778844
    p recomb$72 = 0.019347053748460016

    p fNumScintPhotons$73 = 5.7338241888496153
    p fScintYieldFactor$74 = 1
    p scintYield$75 = 1200
    p fVisibleEnergyDeposition$76 = 0.0047781868240413458
  • PROTONS **************************
    *********************************************************************************************************
    * G4Track Information:   Particle = proton,   Track ID = 1,   Parent ID = 0
    *********************************************************************************************************

    Step#    X(mm)    Y(mm)    Z(mm) KinE(MeV)  dE(MeV) StepLeng TrackLeng  NextVolume ProcName
        0      100    3e+03      750      5.49        0        0         0 volTPCActiveInner_PV initStep
    p fNumIonElectrons$5 = 6049.884891368798
    p fGeVToElectrons$6 = 42370000
    p fEnergyDeposit$7 = 1.0230157258826147
    p recomb$8 = 0.13957458261810568

    p fNumScintPhotons$9 = 200.321439747764
    p fScintYieldFactor$10 = 1
    p scintYield$11 = 1200
    p fVisibleEnergyDeposition$12 = 0.16693453312313666

        1      100    3e+03      750      4.47     1.02    0.138     0.138 volTPCActiveInner_PV LArVoxelReadoutScoringProcess
    p fNumIonElectrons$13 = 6592.6562431224474
    p fGeVToElectrons$14 = 42370000
    p fEnergyDeposit$15 = 1.2544863128665407
    p recomb$16 = 0.1240326549249994

    p fNumScintPhotons$17 = 213.00211024187317
    p fScintYieldFactor$18 = 1
    p scintYield$19 = 1200
    p fVisibleEnergyDeposition$20 = 0.1775017585348943

        2      100    3e+03      750      3.21     1.25    0.143      0.28 volTPCActiveInner_PV hIoni
    p fNumIonElectrons$21 = 5485.4944815419385
    p fGeVToElectrons$22 = 42370000
    p fEnergyDeposit$23 = 1.2879291312276289
    p recomb$24 = 0.10052297936702603

    p fNumScintPhotons$25 = 169.3518757267729
    p fScintYieldFactor$26 = 1
    p scintYield$27 = 1200
    p fVisibleEnergyDeposition$28 = 0.14112656310564409

        3      100    3e+03      750      1.92     1.29    0.109      0.39 volTPCActiveInner_PV hIoni
    p fNumIonElectrons$29 = 2764.953913117854
    p fGeVToElectrons$30 = 42370000
    p fEnergyDeposit$31 = 0.82016207338016811
    p recomb$32 = 0.079566407625292018

    p fNumScintPhotons$33 = 81.139397586916161
    p fScintYieldFactor$34 = 1
    p scintYield$35 = 1200
    p fVisibleEnergyDeposition$36 = 0.067616164655763464

        4      100    3e+03      750       1.1     0.82   0.0508     0.441 volTPCActiveInner_PV LArVoxelReadoutScoringProcess
    p fNumIonElectrons$37 = 2274.9519387938649
    p fGeVToElectrons$38 = 42370000
    p fEnergyDeposit$39 = 1.10391505291379
    p recomb$40 = 0.048638268592278988

    p fNumScintPhotons$41 = 60.034802211339709
    p fScintYieldFactor$42 = 1
    p scintYield$43 = 1200
    p fVisibleEnergyDeposition$44 = 0.05002900184278309

        5      100    3e+03      750         0      1.1   0.0362     0.477 volTPCActiveInner_PV hIoni
        6      100    3e+03      750         0        0        0     0.477 volTPCActiveInner_PV FastScintillation

    Total number of steps was 5

    *********************************************************************************************************
    * G4Track Information:   Particle = proton,   Track ID = 1,   Parent ID = 0
    *********************************************************************************************************

    Step#    X(mm)    Y(mm)    Z(mm) KinE(MeV)  dE(MeV) StepLeng TrackLeng  NextVolume ProcName
        0      100    3e+03      750      5.49        0        0         0 volTPCActiveInner_PV initStep
    p fNumIonElectrons$45 = 5943.6341903663133
    p fGeVToElectrons$46 = 42370000
    p fEnergyDeposit$47 = 0.96551956775751702
    p recomb$48 = 0.14528893102731533

    p fNumScintPhotons$49 = 198.39360724799312
    p fScintYieldFactor$50 = 1
    p scintYield$51 = 1200
    p fVisibleEnergyDeposition$52 = 0.16532800603999426

        1      100    3e+03      750      4.52    0.966    0.138     0.138 volTPCActiveInner_PV LArVoxelReadoutScoringProcess
    p fNumIonElectrons$53 = 6561.4677085593576
    p fGeVToElectrons$54 = 42370000
    p fEnergyDeposit$55 = 1.2019137987799353
    p recomb$56 = 0.12884548678836819

    p fNumScintPhotons$57 = 213.72813747692848
    p fScintYieldFactor$58 = 1
    p scintYield$59 = 1200
    p fVisibleEnergyDeposition$60 = 0.17810678123077373

        2      100    3e+03      750      3.32      1.2    0.144     0.282 volTPCActiveInner_PV hIoni
    p fNumIonElectrons$61 = 1304.6935198041729
    p fGeVToElectrons$62 = 42370000
    p fEnergyDeposit$63 = 0.255961173237922
    p recomb$64 = 0.12030285918912612

    p fNumScintPhotons$65 = 41.864744038358651
    p fScintYieldFactor$66 = 1
    p scintYield$67 = 1200
    p fVisibleEnergyDeposition$68 = 0.034887286698632211

        3      100    3e+03      750      2.98    0.256   0.0279      0.31 volTPCActiveInner_PV hadElastic
    p fNumIonElectrons$69 = 5271.2571076296408
    p fGeVToElectrons$70 = 42370000
    p fEnergyDeposit$71 = 1.295708826267528
    p recomb$72 = 0.096017041102605741

    p fNumScintPhotons$73 = 161.12999583563152
    p fScintYieldFactor$74 = 1
    p scintYield$75 = 1200
    p fVisibleEnergyDeposition$76 = 0.13427499652969294

        4      100    3e+03      750      1.68      1.3    0.103     0.413 volTPCActiveInner_PV hIoni
    p fNumIonElectrons$77 = 3054.0795835411186
    p fGeVToElectrons$78 = 42370000
    p fEnergyDeposit$79 = 1.0539878304836381
    p recomb$80 = 0.068389005647924717

    p fNumScintPhotons$81 = 86.710143696576935
    p fScintYieldFactor$82 = 1
    p scintYield$83 = 1200
    p fVisibleEnergyDeposition$84 = 0.072258453080480775

        5      100    3e+03      750     0.629     1.05   0.0535     0.467 volTPCActiveInner_PV LArVoxelReadoutScoringProcess
    p fNumIonElectrons$85 = 1049.1276508390688
    p fGeVToElectrons$86 = 42370000
    p fEnergyDeposit$87 = 0.6293702959149643
    p recomb$88 = 0.039342651655261671

    p fNumScintPhotons$89 = 26.466590968089378
    p fScintYieldFactor$90 = 1
    p scintYield$91 = 1200
    p fVisibleEnergyDeposition$92 = 0.022055492473407816

        6      100    3e+03      750         0    0.629   0.0158     0.482 volTPCActiveInner_PV hIoni
        7      100    3e+03      750         0        0        0     0.482 volTPCActiveInner_PV FastScintillation

    *********************************************************************************************************
    * G4Track Information:   Particle = Ar40,   Track ID = 2,   Parent ID = 1
    *********************************************************************************************************

    Step#    X(mm)    Y(mm)    Z(mm) KinE(MeV)  dE(MeV) StepLeng TrackLeng  NextVolume ProcName
        0      100    3e+03      750     0.087        0        0         0 volTPCActiveInner_PV initStep
    p fNumIonElectrons$93 = 14.452014305238437
    p fGeVToElectrons$94 = 42370000
    p fEnergyDeposit$95 = 0.08704680382652441
    p recomb$96 = 0.0039184750821310739

    p fNumScintPhotons$97 = 1.2056743291038077
    p fScintYieldFactor$98 = 1
    p scintYield$99 = 1200
    p fVisibleEnergyDeposition$100 = 0.0010047286075865064

#6 Updated by Jason Stock about 1 month ago

I have included and formatted a bit of information from my previous debugging logs while trying to isolate the issue. They should be somewhat readable now.

#7 Updated by Hans-Joachim Wenzel about 1 month ago

Hi

looking at some of the numbers they make sense for the input values:
for protons and alpha the given photon yield is the same, there is no Birks suppression (since the birks constant(s) is not provided anywhere). So the same energy deposition will result in the same number of photons as expected. So no bug here.

now one has to look at the step size and visible energy/step-length for the momentum of the alpha/proton (reproducing bethe bloch) for alphas/protons. This really can not be checked from 1 datapoint but you would need to make a graph or plot. I am pretty sure Geant4 does a pretty job here

#8 Updated by Hans-Joachim Wenzel about 1 month ago

expected stopping power (here for polyethylene) for different particles.

#9 Updated by Jason Stock about 1 month ago

Yes, the values out of Geant appear correct. The issue is with the calculated charge and light yield. You can see on slides 2, 5, and 6 here (https://indico.fnal.gov/event/20584/contribution/1/material/slides/0.pdf) that the overall values from 5MeV alphas are not believable. The charge and light yield from alphas is far too low.

#10 Updated by Hans-Joachim Wenzel about 1 month ago

None of the adc count plots make any sense. But it looks that the problem is farther down the line not in the geant4 simulation or calculation of the photon yield.

#11 Updated by Hans-Joachim Wenzel about 1 month ago

Hi

to check a little bit more I did the following I shoot a proton/alpha with 5 MeV kinetic energy (p0 =0.193 for alpha p0=0.097 for the proton) into liquid Argon. I expect that when I sum up all the Simeenergy deposits that I get 5MeV as the kinetic energy is converted. This is exactly what I see (see attached plots). The only difference is that the alpha deposit all the energy in one step while the proton travels several steps. So as far as the simulation is concerned we can close this report and we should investigate further how the final signal is simulated to arrive at the ADC counts.

#12 Updated by Jason Stock about 1 month ago

We confirmed that the values from the individual G4steps appeared correct already. The point of concern is when ISCalculationSeparate takes the energy deposits and calculates the Scintinlation Yield in the G4LossTableManager and when ISCalculationSeparate calculates the recombination. It appears that calculation at line 127 ( fNumIonElectrons = fGeVToElectrons * 1.e-3 * fEnergyDeposit * recomb; ) is getting an extremely small value for recomb, stemming from the small value of dx (recomb is calculated at lines 115 and 116). The numbers out of G4 make sense. The final number for fNumIonElectrons does not. We believe that the calculation of "recomb" uses an approximation that breaks down for small values of dx.

As to why the scintillation yield is so low, I am not sure what is happening inside of the G4LossTableManager (fEMSaturation in ISCalculationSeparate).

#13 Updated by Hans-Joachim Wenzel about 1 month ago

fEMSaturation = G4LossTableManager::Instance()->EmSaturation();

can't be the source of it because in this case the Birks factor is not defined so Birks suppression is not at play.

I will make a plot of the recombination since the difference that counts is the fact that an alpha particle will deposits all the energy at a very short path compared to a proton.

#14 Updated by Hans-Joachim Wenzel about 1 month ago

I had a look at the paper Nucl.Instrum.Meth.A523:275-286,2004 then I took the Bethe formula and calculated a stopping power of 550 MeVg/cm2 for the alpha and 220 for the proton of Ekin=5MeV. this gives a recombination value of 0.0233957 for the alpha and 0.0487299 for the proton. This looks reasonable the paper lists 0.014 for an 5.64 MeV alpha given a field of 0.5 KV/cm. (If I take a the stopping power from Geant 4 directly I get R= 0.0105). So overall things look they are in the right ballpark.

void recom() {

double fGeVToElectrons = 4.237e+07;
double fRecombA = 0.800;
double fRecombk = 0.0486;
double fModBoxA = 0.930;
double fModBoxB = 0.212;
double EFieldStep = 0.5;
//}
//Double_t boxrecomfun(Double_t *x, Double_t *par) {
double dEdx=550.; // alpha Ekin 5MeV
double Xi = fModBoxB * dEdx / EFieldStep;
double recomb = log(fModBoxA + Xi) / Xi;
cout<&lt;recomb<&lt;endl;
dEdx=220.;
Xi = fModBoxB * dEdx / EFieldStep;
recomb = log(fModBoxA + Xi) / Xi;
cout<&lt;recomb<&lt;endl; //proton Ekin 5MeV
dEdx=1440.;
Xi = fModBoxB * dEdx / EFieldStep;
recomb = log(fModBoxA + Xi) / Xi;
cout<&lt;recomb<&lt;endl; //proton Ekin 5MeV
}

0.0233957
0.0487299
0.0105082

#15 Updated by Kyle Knoepfel about 1 month ago

What is the status of this issue?

#16 Updated by Hans-Joachim Wenzel about 1 month ago

  • % Done changed from 0 to 100
  • Status changed from Feedback to Resolved

I had a look at the paper Nucl.Instrum.Meth.A523:275-286,2004 then I took the Bethe formula and calculated a stopping power of 550 MeVg/cm2 for the alpha and 220 for the proton of Ekin=5MeV. this gives a recombination value of 0.0233957 for the alpha and 0.0487299 for the proton. This looks reasonable the paper lists 0.014 for an 5.64 MeV alpha given a field of 0.5 KV/cm. (If I take a the stopping power from Geant 4 directly I get R= 0.0105). So overall things look they are in the right ballpark and the model describes the physics as well as we know it.

#17 Updated by Jason Stock about 1 month ago

The Low Energy Physics Reco team with DUNE is still discussing the issue. There are still people that want to discuss what is going on.

#18 Updated by Kyle Knoepfel 17 days ago

  • Status changed from Resolved to Under Discussion

Hans, Jason, can you give an update on this issue?

#19 Updated by Hans-Joachim Wenzel 17 days ago

Implemented both NEST and ISCalculationSeparate (BOX recombination) in the new larg4 framework. But the results look very similar. The CPU time for 1000 evts is minutes in case of NEST and seconds for the Box algorithm. My plan is to clean up the code, put in all the hooks to configure it and make it available.
But it definitely looks like both algorithms predict the alpha to be very suppressed. So as far as I am concerned one nearly needs to look into the physics, make measurements of alphas in liquid Argon TPC's and if necessary come up with a better algorithm that describes the recombination for highly ionizing particles. This is a physics not a software issue.

NEST BOX
em. option default emz default emz
Nr. of Photons 2.531e5 2.531e5 1.997e5 1.997e5
Nr. of electrons 2934 2961 2736 2770
time 5:28 minutes 3:08 minutes 16 sec 16 sec

#20 Updated by Kyle Knoepfel 10 days ago

Given that this now seems to be a physics simulation issue and not a programming bug, is it acceptable to both of you to close this issue?



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