Recent Upgrade of g4lbnf: Horn B & C, Conceptual Design revision - - PowerPoint PPT Presentation

January 5 2017 Realistic Horns in G4LBNF 1

Recent Upgrade of g4lbnf: Horn B & C, Conceptual Design revision 2

Paul Lebrun ND/Fermilab.

January 5 2017 Realistic Horns in G4LBNF 2

Outline

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Horn B & C, revision 2 => Coded up. ==> geantino plots

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(Horn A, small improvements to the code. )

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Comparison, Horn “ideal” (as coming out of the genetic algorithm based optimization

• f Laura F. et al) vs “Realistic”, detailed G4 implementation of all “relevant” volumes

found in the NX-9 CAD model, and corresponding changes to the magnetic field map.

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Next steps:

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Retune a bit (spacing between horns, horn current..)

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small changes in horn length??? Is this worth trying?

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Study the effect of field maps upgrades in the Inner/Outer conductor regions, and other non-unformities

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Realistic Beam window, Rev X. ?

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… Few programming notes..

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Now using Geant4 v 4.10.2.p02 .. The change I made to the code caused crashed using the previous release, due to bug in the G4 geometry navigation code, fixed months ago...

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So, I am using ROOT 6.x, and a newer compiler, as I haven't found a matching DK2Nu with the old old ROOT and this new compiler.

– This might break the old style nutrino N-tuples code. My

advice: use the Dk2NU package from now on.

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I haven't not yet committed the changes.. Bigger change then just G4. Laura F. has upgraded our neutrino analysis script(s), but... is it in use??

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… Coding the realistic geometry..

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No changes in the methodology.. Fired up the Citrix server, TeamCenter, get to the model #, run Nx9, and do the measurements that are needed.. TeamCenter Doc# entered in the code.

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Enter the geometry, mostly “hardcoded” in the LBNEVolumePlacements class. One by one, trying to check every number twice...

– Curves ==> Polygonal shape.

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Conceptual Design Rev1 no longer avialable at run time: if needed, you'll need to re0build g4lbne from a previous release (v3r4p4 ?.. )

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(a good thing a few of us will stay around for the next ~30 years).

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Nx9 screen captures... (Horn B)

I/O trans. Outer Conductor Inner Conductor Current Eq section 1 m. I/O Insulator

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..found wire frame a bit more convenient..

Nx9 has good interactive feature to explore the model...Not all features are implemented in the G4 model: simplified some curve, beveled edges for flanges. Also, drain holes not implemented Hanger rings Welds

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..comparison with Geantinos plots..

Nx9 cut view G4lbnf geantinos R/Z plot Spider hanger added.. (NuMI)

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For sake of completion, HornA.

Nx9 cut view G4lbnf geantinos R/Z plot Spider hanger added.. (NuMI) “tapered geometry”

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Note: The upstream Inner/Outer transition, and associated flanges, are crudely represented in G4blnf, simply because they upstream of the starting point of the target. The 4 titanium tubes that support the downstream end of the target, and provide Helium gas for cooling are not shown in the previous slide, but are implemented in the both the NX9 and G4lbnf models.

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Horn C.

G4lbnf geantinos R/Z plot Spider hanger added.. (NuMI) Current equalizer sections, upstream

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Neutrino (in neutrino mode) spectrum, far detector.

Idealistic vs Realistic

Simply replace the Idealistic (as taken of the “run26_8079_NumiTarget” from Laura). All horns are either “ideal” shape (polygonal, from the optimizer) or Realistic (Nx9 models) . All realistic horns are revision 2.

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Neutrino (in neutrino mode) spectrum, far detector. Idealistic / Realistic

Simply replace the idealistic horns, as specific in “CP_run26_8079_NumiTarget.mac” Laura gave us (Cory C., my self), by the “Nx9-based” G4 implementation. Note: All Horns are at Rev 2 (Team Center #F10068454, #F10071359, #F10071767) respectively.

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Neutrino (in neutrino mode) spectrum, far detector, December 2016 Idealistic / Realistic

About 3 weeks ago, Horn C was at revision 1 ! In addition Horn B, realsitic, was placed such that the Inner conductor (not the upstream I/O transition dumbbell) starts exactly at at the same place as the idealized (straight, vertical I/O section) configuration beanding in the I/O section occurs → differently.

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Details needed! Current status... Replacing back one horn by it's idealized version.

After these corrections, Horn A shape and field integral seems to matter most for the trailing edge of the focusing peak.

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An other way to compare.. : One horns “realistic”, two “idealized”

Indeed, the focusing difference at 3.75 GeV is due to HornA shape difference.. Is this worth addressing ? Overall, as we added material with the realistic version, we loose neutrinos at low energy, in the focusing peak, and gain a tiny bit at high energy..

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Effect of downstream target support..

<~ 1 % change across the spectrum! Perhaps sensible: In the focusing peak, pions at a bigger radii than the bulk of the support, which at a Radius of ~ 40 mm. Not affected.. At higher energy production of pions that can be focused by HornC do compensate the absorption. And, of course, no magnetic effects.

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Focusing changes: Effective magnetic length of horns.. Ideal vs realistic..

In the ideal version, the I/O transitions region are much simplified, they are nearly vertical

• lines. We (Cory C. ? ) could compromise and reduce a bit the length of the IC, to match

the same B.dl that enter (or leaving) the I/O transition..

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Impact on the Near to Far ratio.

This is the ratio of ratios previously shown, Near over Far. As expected, Horn A shape change induced the largest effect at 2.5 GeV (not really the falling edge of the focusing peak, so it matters... )

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While we hope that the above 3-horn configuration will be the selected one, we still have to support the CDR Baseline, i.e., the good old NuMI horn and target, adapted for 1.2 MW

• pration.

Andm since we haven't run this configuration in many months, it felt into disrepair... Note: we can't simply take the old CDR flux plot, as the Hadronic interaction modeling changed on us. ==> Re-furbish the broken stuff. Two distinct projects:

• a. Port an old version (v3r2p6) to Geant4.10.2p2. Upgrade it to support the current

capabilities of LBNEAnalysis, based on the current Dk2Nu.

• b. Extract the 1.2 MW NuMI target code, circa ~2014, from the above version, and

re-implemented, optionally, of course in the current version of g4lbnf.

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Recap: ~ 4 years of history.. refurbised v3r2p6.

This is the ratio of the fluxes, far detector, obtained using the optimized, realistic horns,

• ver the one using the NuMI configuration found in release v3r2p6 (~ 3 to 4 years

ago). The same version of Geant3, v4.10.2p2 is used, along with the Dk2Nu library.

Preliminary!.....It may change in the next few days.

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Next Steps...

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Must finish the old NuMI retro-fit, and related checks in the current version of g4lbnf. My 2nd priority in the next few weeks...

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Do we need to retune a bit, if the shape of the focusing tail matters? By this, I mean moving Horn B with respect to Horn A, (easy), or reducing the length of the IC by a few percent? (need to redo the FEA analysis.... Probably not !... )

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Study the field maps, and corrections due to horn deformations, I/O transition regions, etc.. (Colorado, UTA & IIT )

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??

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So, what should be my 1rst priority?

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Who knows..

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Meanwhile, I did some work on the “spectrometer”.

– Should we opt (in a month or two, w'll know) for the ex-situ option, how

to cross-check or tie-in, the results from the replica to the real chase?

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Proposal (Alberto M., mostly..) :

• Install a small, relatively thin “ionization detector” at the back of

the HornC, where, in the replica, the full spectrometer will be installed.

• The very same detector would be installed in the Chase.
• Concept: the flux of ionizing particles is good tracer of the

charge pi/kaon/muon flux, in the chase. Only if well calibrated to the real flux of these neutrino progenitors.

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So, here is what I did in g4lbnf: Usual Chase content (target, 3 horns, details don't matter) Re-check so-called “tracking planes”, recording every (as the 50 MeV threshold is removed ) ionizing particles that goes through them. ==> ability to determine the ionizing particle rate, per PoT. Imagine now a ultra fined grained detector, basicaly digital, (not calorimetric!), such as Silicon Pixel planes used at LHC (pixel size 50 by 100 microns) . Take an active surface

• f 5 cm2. If we have ~ 5 e5 proton per rf bucket during the ~ 100 microsecond horn pulse,

that is, we do slow extraction with the the minimum workable beam intensity in MI, and extract for ~ 1 second, then The probability to get a pixel “on” is of the order of 1, for radial distance greater 40 cm. With plenty statistics, one valid measurement pe MI ramp.

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Profile of the probability for a pixel hit vs X

Assuming the instantaneous beam intensity expressed in the previous slide...Rate will be dominated by soft e.m., from π0 decays radiating away on the horns. But, π0 are good tracers

• f π+