garsoft update jun22 2018 - fermilab...telsa misunderstanding) – 4 tesla to do list as of june 13...

GArSoft UpdateTom JunkHPGTPC MeetingJune 22, 2018

ALICE TPC GDML

June 22, 2018 Tom Junk | HPGTPC Simulations2

Running ALICE code leaves a geometryrootfile ("geometry.root")in the working directory.

Using TGeoManager's tools, a GDMLfile can be exported: hpgtpc_v1.gdml

I checked for overlaps and found afew (maybe an artifact of the GDMLcreation), and removed the offendingpieces.

I put in a rotation of 90o so that x pointsalong the drift direction and z pointsapproximately along the beam. y stillpoints up.

I changed the gas to 10 Bar of 90% Ar and10% Methane (by weight I think).Called "TPCGas"

Output of TGeoManager::Draw()units are cm

From the ALICE TPC TDR


CERN-OPEN-2000-183

Zooming in on the edge

Are these allreal channels?Some areawfully thin!

• I suspect these are just being blockedby the 12 mm cover electrode.

• There's a 3 mm gap between sectors(assume constant width). I defined channelsall the way to the edge (going to have someextras).

• Partially obscured channels may collect less charge.

A First Attempt at a Channel Grid


292140 x 2 =584280 channels(c.f. 557568 in ALICE, or about 4.6extra per pad row)

18 sectors

63 pad rows onthe inner chambers,

64 pad rows inthe inner outerchambers

32 pad rows in theouter outer chambers

A Simplified Geometry• The cylinder inside the inner field cage wasn't easy to add in a

way that preserved uniform gas volume• Inner field cage won't be

needed for the HPGTPC ND

• I found the GDML manual and made some tubesby hand.

• Added a 30-cm thick ECAL made out of 10 g/cm3

Pb-C-H mixture• ECAL stops particles

(otherwise they loop)


Filling the Hole


• Rectangular array of pixelsin a disk

• Pixel size: 6mm x 6mmc.f. 4 mm x 7.5mm for innerpad rows.

• Central disk has 62060 padsper detector side.

• Total channels per side isnow 354200. About 18%of channels are in the disk.

Software Improvements• GArSoft came with a raw::RawDigit data product similar to the LArSoft one

• I added zero suppression, a feature used by ALICE. I (mostly) copied the LArSoft ZS algorithm (J. Insler)

• Adjusted the electrons to ADC conversion factor (what is the gas gain?) and the drift velocity. Still unknown. 0.2 cm/!s assumed for now.

• For now, the noise is turned off, so the gas gain just needs to be big enough for hits to pass the zero-suppression threshold.

• Added a magnetic field of 0.4 Tesla (interface already in nutools, butuniform magnetic field only)

• Upgraded to art v2_22_02 and nutools v2_23_02, so we can shoot monoenergetic neutrinos at the detector.

• Tested GENIE interface• Stepsize limit of 2mm as a fcl parameter (already in GArSoft)• Resurrected the 3D event display and added an ALICE wire frame

• Fix bugs


My First Event in the new 3d Event Display


• 1 GeV Muon• MC Truth being shown here• Original ALICE geometry with no ECAL – muon just loops and loops• Oddly connected lines between track

segments.

• n.b. B Field too strong (kGauss vs.Telsa misunderstanding) – 4 Tesla

A Second Try• New geometry with ECAL• GENIE !eCC event• MC Truth• Particle species colored

differently.red:electronspurple: protonsgray: neutronsblue: muonsn.b. B Field too strong (kGauss vs.Telsa misunderstanding) – 4 Tesla


Another !eCC Event


Gray neutronsmore visible here

One of the neutrons scattersin the GAr.

n.b. B Field too strong (kGauss vs.Telsa misunderstanding) – 4 Tesla

Adding Raw Digits in Green


And also Gray for

the 2D projection

on the readout planes

Uses the channel geomety,

raw::RawDigit simulation,

and a drift model.

I had to cheat the event

time however.

A 10 !s beam spill window

width causes visible

displacements

in raw digits.

Visible when overlaying MC Truth,

but also visible for cathode-crossing tracks

n.b. B Field too strong (kGauss vs.

Telsa misunderstanding) – 4 Tesla

To Do list as of June 13• Parameterize vdrift as a function of pressure, temperature, and voltage• Check/update parameterization of diffusion

• Write hit-finder, cluster finder.• Evaluate/update track data product• Evaluate tracking algorithms. Many available from

colliders and other magnetized gaseous trackers.

• dE/dx-based PID studies

• Add hits and tracks to the event display.• Model projective pads and partially obscured pads• Put in pressure vessel, more realistic ECAL, magnet yoke and coils• Add photon detectors

• Run MC and characterize performance

• Add ECAL readout• Integrate with ArgonCube software


I worked on these three sincethe ArgonCube Meeting

Hit Finder• Simple initial hit finder -- Just use the Zero-Suppressed blocks

of Raw Digits to make hits.• Threshold applied when making zero-suppressed blocks. 5

ADC counts in simulation. No noise, so no fake hits.• 5 extra ticks before and 5 after the above-threshold region to get

sub-threshold tails.• Added Integral and RMS data elements to rec::Hit. Existing

elements: channel, position, start time, end time• Found that the event display shows hits already


A nueCC Event with Hits• 0.4 T this time! (I think...)


Many fewer hitsthan channes x ticks

Two Zooms on that Event


Hits are located at the pad (y,z) locations, and arrival time gives x.Grid pattern noticeable on tracks. Distribution in x is much narrower

Initial Track Finder and Fitter• Start with Hits à Make Tracks• Pattern Recognition Step: Want homogeneity and isotropy- Sort hits in X (drift direction = E field direction – B field direction)

- Loop over sorted hits. Add hits to tracks if hit is near the last one added to that tracks. Make a new track if hit is too far from any track in the list

- Rather naive – follows kinks, may have delayed split, may get confused by delta rays

• Extended Kalman filter track fitter- Initial version included in tracker1_module.cc - Five track parameters – as a function of x, have (y, z, curvature, phi,

slope)


Delta Ray


I dont have a trackdisplay yet, butwas stepping throughthe Kalman Filter,I noticed the trackparameters tooka swing after thefirst few hits.

Tracker To-Do• Fit tracks in both directions. In a collider, we know which way the

tracks go. Here, not so much.• Add parameters evaluated at both ends or along the way to the track

data product. Add track-hit associations.

• Look at displaying tracks in the event display

• Cluster hits into "clusters" a la ALICE. Diffusion spreads out charge among many pads. Clusters are easier to track than pad hits.

• Improve pattern recognition- Start new tracks if angle changes too much – especially important near

primary vertex- Prune delta rays.- Deal with very low Pt curlers (are they really straight or corkscrews?)


Housekeeping• I updated the wiki at

https://cdcvs.fnal.gov/redmine/projects/garsoft/wikiwith getting-started info and how to get the code and build it

• scisoft instructions are out of date• Perhaps ready to tag and release the first version.• We should maintain prebuilt releases on CVMFS in the DUNE

area.


https://cdcvs.fnal.gov/redmine/projects/garsoft/wiki

garsoft update jun22 2018 - fermilab...telsa misunderstanding) – 4 tesla to do list as of june 13...

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