Near Detector Optimization Task Force · Near Detector Optimization Task Force Draft Charge to the...

Near Detector Optimization Task Force

Steve Brice, Daniel Cherdack, Kendall Mahn


Draft Charge to the Task Force

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❑ The near detector optimization task force is charged to:▪ Develop GEANT4 simulations of the reference design near detector and

possible alternatives▪ Perform a full end-to-end simulation connecting the measurements in the

near detector to the far detector systematics using, for example, the VALOR framework

▪ Evaluate the potential benefits of augmenting the reference design with• a LAr-TPC• the use of a High Pressure Gaseous TPC

▪ Produce a first report on their findings to the DUNE Technical Board by September 2016 and a final report by March 2017.

Near Detector Optimization Task Force3

Simulation and Analysis Path

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VALOR: ND Constraints - Costas Andreopoulos


Points of Contact

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Flux: Laura FieldsInfrastructure: Robert HatcherCross-Section Models and Systematics: Kendall Mahn → (Rik Gran & Steve Manly)FGT simulation: Tyler AlionLAr simulation: Sarah Lockwitz & James SinclairGAr simulation: Justo Martín-AlboVALOR: Steve Dennis & Lorena Escudero & Costas AndreopoulosFD Simulation: Tingjun Yang & Tyler AlionFD Fit: Daniel CherdackFigures of Merit: Brian Rebel

• The points of contact are fully populated, but there is need for more effort within each of the 3 ND simulation efforts.• Particularly improving the recon modeling and sample selection

• Detailed task list can be found at https://docs.google.com/spreadsheets/d/1_oYzHaDXz5M55cAlSYISWcdD31SAZOYiuIHt-TAvpy0/edit#gid=642779652

https://docs.google.com/spreadsheets/d/1_oYzHaDXz5M55cAlSYISWcdD31SAZOYiuIHt-TAvpy0/edit#gid=642779652




Phase 1 - focus on machinery Sept 2015 - Jan 2016

• Milestone 1: First complete run through of the machinery (before Arlington meeting)• Jan 2016

Phase 2 - incrementally add the necessary physics and improve simulations Jan 2016 - Sept 2016

• Milestone 2: 2nd run through (before SURF meeting)• April 2016

• Milestone 3: 3rd run through to generate material for initial report (before FNAL meeting)• August 2016

• Milestone 4: Initial Report• September 2016

Phase 3 - final improvements to the physics and simulationsSept 2016 - Mar 2017

• Milestone 5: Final run through to generate material for final report (before CERN meeting)• December 2016

• Milestone 6: Final Report• March 2017

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1st Run Through

● 1st Run Through completed in January

● As promised not much physics, but a great deal learned about making the whole processing chain work○ Can handle error matrices of size O(100) ○ Detector geometries up to scratch○ Understand event simulation rates○ Simulations able to communicate with VALOR○ VALOR output works in Final Fit○ Able to properly correlate systematics in near and far detector○ ….

● 1st Run through described in detail in 18 page doc https://docs.google.com/document/d/1TfXRqqIc2Xj4j2_GucaDqG9F30Q3xdT6Czxs30mEXXQ/edit#heading=h.sudj0au3oi0p

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https://docs.google.com/document/d/1TfXRqqIc2Xj4j2_GucaDqG9F30Q3xdT6Czxs30mEXXQ/edit#heading=h.sudj0au3oi0p

https://docs.google.com/document/d/1TfXRqqIc2Xj4j2_GucaDqG9F30Q3xdT6Czxs30mEXXQ/edit#heading=h.sudj0au3oi0p


2nd Run Through

● 2nd Run Through completed last month

● Upgrades from 1st Run Through○ Flux and Flux errors unchanged○ Small geometry upgrades to the 3 detectors○ Cheated detector reconstructions implemented○ First pass at ND sample selection defined and used○ Cross-section uncertainties defined and a priori error matrix formed○ VALOR fully run to produce output error matrices constrained by ND

simulated data○ Far detector PID improved○ Far detector fit finished and benchmarked against CDR fits○ Thought started on Figures of Merit

● 2nd Run Through being described in detail in https://docs.google.com/document/d/1CNEO8xW06ooCEG3YG0AKtUdvLFuWO3GN-wGLEwdetO0/edit#

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https://docs.google.com/document/d/1CNEO8xW06ooCEG3YG0AKtUdvLFuWO3GN-wGLEwdetO0/edit#



The Flux Prediction - Laura Fields

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Neutrino fluxes used in the 2nd Run Through are the same as those used in the 1st

Will upgrade to Laura’s optimized flux for the 3rd Run Through


ND Task Force Approach to Reconstruction

● We have a generic problem across the 3 ND options and the FD -

“How do you provide the best mimic of the reconstruction and PID algorithms we will have 10 years from now?”

1) Use the best algorithms we have now

2) Use our experience with past detectors and algorithms toappropriately smear truth quantities

● For all 4 reconstruction efforts (3ND + 1FD) we are evaluating each required observable individually, and:○ Use 1) whenever practical, although this may be limited, esp for the 3 ND

options○ Use smearing that is well informed by studies of the full GEANT4

simulations and consistent with 2)○ Rely upon 2) fully when extracting relevant information from the full

GEANT4 simulations presents difficulties beyond the scope of the TF

“Cheating but not lying”

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LAr Simulation - James Sinclair and Sarah Lockwitz

● Transitioning away from the

MicroBooNE geometry used in

1st Run Through

● Starting to implement the

modular ArgonCube proposal

● Generated 107k neutrino spills

and 100k anti-neutrino spills

● Used 7.5x1013 POT per spill

● 1.2 Million nu interactions;

790k anti-nu interactions

● Used a fiducial volume of 2.56 m (drift) x 2.3 m (height) x 10.36 m (beam dir)

● No magnetic field in this iteration

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LAr Reconstruction - James Sinclair and Sarah Lockwitz

● Using smeared MC Truth in this iteration

● Energy is smeared with a Gaussian

● Vertexing taken from truth

● A handle for overlapping energy is in place to help take account of the pile-

up issues

● Machinery is in place to upgrade the reconstruction – no need to rewrite

analysis framework

● Real resolution of readout will be measured in the upcoming test at LHEP

Bern. (June/July)

● Pixel readout system to be implemented in LarSoft as part of ArgonCube

project

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FGT Reconstruction and PID - Tyler Alion

● Geometry essentially completeand unchanged from the 1st RunThrough

● Reconstruction smearing

○ dE 5%

○ Muon p 3.5%

○ Pion p 7.5%

○ Proton p 5.5%

○ Electron p 12%

● Few reconstruction effects accounted for yet. Tracks that overlap shower. Decays in straight lines. We need to account for these

● PID cheating

○ No transition radiation used yet

○ Uses smeared dEdx lookup

+

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FGT Event Display - Tyler Alion

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GAr TPC Simulation - Justo Martín-Albo

● Simulated about 0.5E19 POT: some 20K Ar interactions in neutrino mode and 10K in antineutrino mode.

● Most interactions occurring in magnet, and about 0.2% in argon gas target.

● Followed brute-force approach for event generation:

○ Let GENIE generate all interactions in the detector for a given POT statistics; simulate interactions with Geant4, distributing them in different spills for event mixing.

● Too CPU-time consuming. We’ll follow different strategy for 3rd run-through, reusing collections of “non-interesting” interactions.

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GAr TPC Reconstruction - Justo Martín-Albo

● Momentum Resolution○ From T2K-ND280:

σ(S) = 0.05 mm, σ(x) = 0.6 mm.○ Assume that total momentum

resolution is approximately equal to transverse momentum resolution.

● PID○ Use of Geant4 energy

deposits to calculate dE/dx for particle identification comparing with look-up tables previously built.

● For 3rd Run Through plan to use reconstruction packages RECPACK and TREx○ Fall back to cheated quantities as a plan B if needed

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FD Simulation & Reconstruction - Tingjun Yang & Tyler Alion

Taken from Karl Warburton’s MCC6 talk

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FD Electron Neutrino Selection - Tyler Alion

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A Priori Uncertainties - VALOR (Lorena Escudero)

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Total covariance matrix with prior uncertainties, input to the VALOR DUNE ND fit:

156 parameters - 104 flux - 43 interaction model - 9 detector efficiencies

(each block added diagonally)


A Priori Flux Uncertainties - Laura Fields

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Full NuMI Error Matrix borrowed from MINERvA give ND error matrix

A few simple assumptions allows it to be expanded to become a full flux error matrix for both ND and FD

● The Flux Error Matrix used in the 2nd Run Through is the same as that used in the 1st

● For 3rd Run Through we hope to upgrade to an error matrix produced for DUNE rather than one stolen from MINERvA○ Work of Amit Bashyal - see Laura’s talk from Friday


A Priori Cross-Section Uncertainties - VALOR (Lorena Escudero)

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● Variations of GENIE model parameters are translated into a full error matrix in the above, more generic parameters

● This is a first pass at a largely model independent characterization of cross section uncertainties


A Priori Cross-Section Uncertainties - VALOR (Lorena Escudero)

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Correlation matrix

1 uncertainties


VALOR - Lorena Escudero, Steve Dennis, Costas Andreopoulos

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VALOR Samples - Steve Dennis

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Example of VALOR Samples: GAr TPC, Neutrino Mode

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The Output Uncertainties - Steve Dennis

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● Clearly there’s a problem!● Output uncertainties are unrealistically tiny● Cause(s) being investigated● A number of known problems with the input samples● The method and results are fully documented in a tech note http://bit.ly/1WHRBjD

http://bit.ly/1WHRBjD


The Long Baseline Analysis Fitter (LOAF) - Dan Cherdack

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● The Constrained error matrices produced by VALOR are passed onto LOAF

● LOAF combines the FD simulated samples and the VALOR constrained error matrix to do an oscillation fit

● Comparison of LOAF and CDR fit results○ unfortunately different fluxes were used for the two - will be fixed


Final Sensitivities for each ND Option - Dan Cherdack

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● Trouble producing a usable LAr error matrix from VALOR restrict the comparison to HPTPC and FGT

● Unrealistically small errors for both HPTPC and FGT mean they have the same sensitivity and it exceeds the CDR sensitivity

● We’re working on it!

• It would be good to understand who in the long-term will be responsible for ND simulation, the TF or the WG?– TF doesn’t exist beyond March 2017– Should be absorbed into Computing and Simulation structure

• It is unclear how the results from the beam optimization will be taken into account in the analysis of the TF– 3rd run through will use optimized beam– Future iteration of beam optimization using xsec errors advisable

• Neutral particles are not accounted for in detail– Not sure what is meant here– They are handled as well as GEANT4 is able

1/12/2016LBNC Closeout: DUNE29

ND TF Comments from Jan LBNC Meeting(Brice comments in blue)

• Non-beam backgrounds should be considered– Cosmics and Rock events are being incorporated into 3rd RT– Matt Bass at Oxford producing cosmics– Jarek Novak at Lancaster producing rock events

• Vertex activity will be crucial to understand nuclear physics uncertainties– Yes

• It is unclear where the cross section expertise resides, since there appears to be no dedicated cross section/neutrino nuclear interactions working group– ND Physics WG is assigned to handle cross-sections


ND TF Comments from Jan LBNC Meeting(Brice comments in blue)

• Clarify information flow from/to and interaction with near detector working group.– Interaction is very weak– Meetings of NDWG and NDPWG are occasional– TF has made some use of their meetings to discuss specific

issues• e.g. next 3 weeks of NDPWG meetings will discuss

recon/cheating from the 3 ND technologies

• Given the tight timeline prioritizing the goals seems indicated.– The adjustable aspect of the TF output is the quality/detail of

the simulation/recon/fitting.– Prioritisation of this quality/detail is happening (e.g. focus on

recon/cheating rather than simulation)


ND TF Recommendations from Jan LBNC Meeting(Brice comments in blue)

• Close collaboration with the cross section working group needs to be maintained

• Investigate the possibility of a central (between ND/FD) working group for cross sections/neutrino nucleon interactions, to capture all available expertise in one entity


ND TF Recommendations from Jan LBNC Meeting(Brice comments in blue)


Summary● The 2nd Run Through of the processing chain is complete

○ Being fully documented at https://docs.google.

com/document/d/1CNEO8xW06ooCEG3YG0AKtUdvLFuWO3GN-wGLEwdetO0/edit#

○ Full detail on the VALOR piece at http://bit.ly/1WHRBjD and in DOCDB soon

○ We have some problems to solve

● The task force has made great strides with each step in the chain having strong leadership and significant effort

● The reconstruction of ND events is a tremendously challenging task that is at

the heart of the TF goals and we would benefit from an influx effort and

expertise on ND reconstruction over the next 3 months for all 3 ND options

● 3rd Run Through scheduled just before the next Collaboration Meeting● Initial Report due September, final report due March




http://bit.ly/1WHRBjD


Backups


• The Task Force will evaluate ND options based just on science• Budgetary and other concerns can wait• Task force charged with making science based recommendations and any

decisions by the collaboration will likely include other factors.

• Near Detector performance is judged by its ability to improve the sensitivity of DUNE to CPV• Any Near Detector optimized this way will be very capable of the other analysis

envisaged for the Near Detector• Sensitivity to other physics will be a secondary consideration; cannot degrade

oscillation physics

• The ND should allow for measurements on the same target nucleus as the FD (Ar)• T2K oscillation systematics increased by target nucleus differences• Should include a clear and proven path to extracting cross section

measurements on the target nucleus

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Axioms


How to Optimize the CP Violation Oscillation Analysis

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• Adopt and extend the approach of the experiment that is presently at the cutting edge of this work – T2K

• Use the VALOR package for ND fits• Inputs

• Event samples from simulations of the Near Detector options• Detailed systematic uncertainties (spectral changes, and priors)

• Outputs• Fits of all possible nuisance parameters for a FD fit• A covariance matrix that encodes all prior and correlations

• Oscillation parameter fits with FD event samples• Several current tools in use and development• A full VALOR ND+FD fit is also a good possibility

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