A pion beam line option for LBNF - nuPIL
Outline • Introduction • Updated design overview • Neutrino flux comparison • Physics comparison • Details of design • Engineering considerations • Conclusions and moving forward July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 2
Credits Jean-Baptiste Lagrange Jaroslaw Pasternak Imperial College London Total effort is only ~ 1.5 FTE AB Pilar Coloma Ao Liu David Neuffer Milorad Popovic (working on independent concept) Fermilab Terry Hart University of Mississippi Elizabeth Worcester BNL July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 3
Introduction • The basic concept is to design a sign-selected, large acceptance (transverse and in momentum) pion beam line. – neutrinos from a pion beam line: nuPIL • Send only pions in desired momentum range towards DUNE detector (40kT LAr assumed in what follows. – Of course, protons/kaons/muons in the same momentum band will follow along • Ideal configuration: have a 5.8 o bend matched into a straight transport beam line (~200m) • Basic design evolved from the pion injection beam line for nuSTORM. July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 4
nuPIL advantages I Beam systematics • Beam systematics concerns for conventional horn-focused ν beam line: – Secondary particle production • Particle types, flux and energy distribution – Proton beam targeting stability – Target degradation/change – Horn stability – Target/Horn module mass uncertainty • Water, supports, etc. • Since the pion flux is measured in situ by the beam line instrumentation (flux, momentum distribution, emittance), the above are largely factored out. – Some R&D on instrumentation is needed, but work began and vendor contacts have been initiated. – Can also include commissioning/calibration runs that utilize destructive (for the beam) instrumentation • In addition the ν background in the anti- ν beam (& vice versa) is significantly reduced – Some issues with new bend lattice July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 5
Beam systematics II Diagnostics Instrumentation for the beam line (straight) Quantity Detector(s) Comments Beam Intensity Beam current <1% resolution obtainable transformers Beam Position BPMs 1 cm resolution Beam profile Scintillating screens, etc Destructive Energy Polarimeter <1% resolution Energy spread Profile measurement in bend Beam loss Conventional Timing Conventional Pion/proton separation nuSTORM study • Beam can be fully characterized, including Parameter Uncertainty destructive methods during a commissioning Intensity 0.3% phase Divergence 0.6% • Magnet currents can be monitored and controlled with precision Energy spread 0.1% • all magnets are DC Total ≤ 1% July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 6
Update since May CM • New bend with wider momentum acceptance • Horn optimization for this bend – 4 λ long C target • Match into straight beam line • Transport (~200 m) in beam line July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 7
nuPIL ν flux comparison May CM & now This represents a 42% increase in flux July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 8
nuPIL Lattice13-Hybrid vs. LBNF/DUNE 3-Horn Opt July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 9
CP violation sensitivity from Elizabeth W. • Sensitivity calculations CP Violation Sensitivity CP Violation Sensitivity produced by Elizabeth Worcester 8 8 DUNE Sensitivity CDR Optimized Design • Flux for LBNF beams Normal Hierarchy 3-horn Optimized Design produced by Laura Fields 7 7 3.5+3.5 + years ν ν nuPIL Design 2 sin 2 = 0.085 θ • Flux for nuPIL beam provided 13 2 sin = 0.45 θ by Ao Liu 23 6 6 • Unless otherwise noted, all 5 σ configurations (GLoBES code, 5 5 oscillation parameters, 2 2 χ χ systematic selection ∆ ∆ 4 4 = = efficiencies, etc) are identical σ σ to those used in the CDR 3 σ 3 3 • LBNF optimized: identical to “optimized design” in CDR, 2 2 but with 204 m DP • LBNF 3-horn optimized: 1 1 updated LBNF optimized design with improvements 0 0 including, but not limited to -1 -0.8 -0.6 -0.4 -0.2 -1 -0.8 -0.6 -0.4 -0.2 0 0 0.2 0.4 0.6 0.8 0.2 0.4 0.6 0.8 1 1 moving to 3-horn design. / / δ δ π π CP CP July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 10
Hierarchy Mass Hierarchy Sensitivity Mass Hierarchy Sensitivity 25 25 DUNE Sensitivity CDR Optimized Design Normal Hierarchy 3-horn Optimized Design 3.5+3.5 + years ν ν nuPIL Design 2 sin 2 θ = 0.085 20 20 13 2 sin = 0.45 θ 23 15 15 2 2 χ χ ∆ ∆ 10 10 5 5 0 0 -1 -0.8 -0.6 -0.4 -0.2 -1 -0.8 -0.6 -0.4 -0.2 0 0 0.2 0.4 0.6 0.8 0.2 0.4 0.6 0.8 1 1 / / δ δ π π CP CP July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 11
3 σ coverage over 75% of δ range (Pilar Coloma) 6 5 4 3.5 + 3.5 years σ 3 2 NuPIL - Latt.13 1 DUNE CDR 0 0.0 0.2 0.4 0.6 0.8 1.0 �������� �� δ �� July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 12
Normalization uncertainties • I also asked Elizabeth to plot a case with the current estimates for the normalization uncertainties for LBNF/DUNE and nuPIL/ DUNE – LBNF/DUNE: Taken from the case made in the CDR = 5 ⊕ 2 – nuPIL: With beam line instrumentation and from studies done for nuSTORM: 4.5 ⊕ 1.5 • This was done for a large exposure – 10.4 + 10.4 years July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 13
CP Violation sensitivity CP Violation Sensitivity CP Violation Sensitivity DUNE Sensitivity CDR Optimized Design 12 12 Normal Hierarchy 3-horn Optimized Design 10.4+10.4 + years nuPIL Design ν ν 2 sin 2 = 0.085 θ CDR norm. unc. 13 2 sin θ = 0.45 10 10 Est. nuPIL norm. unc. 23 8 8 2 2 χ χ ∆ ∆ = = 6 6 σ σ 5 σ 4 4 3 σ 2 2 0 0 -1 -0.8 -0.6 -0.4 -0.2 -1 -0.8 -0.6 -0.4 -0.2 0 0 0.2 0.4 0.6 0.8 0.2 0.4 0.6 0.8 1 1 / / δ δ π π CP CP July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 14
EW’s plot shown at CM • The take away from this plot is that if, for some reason, your normalization uncertainties are larger than anticipated, the precision of this measurement will degrade quickly • Starting off with anticipated smaller normalization errors leaves more room. • A well controlled measured beam line as in nuPIL has the potential to be a great advantage July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 15
Configuration Details
Schematic Section view • Target Hall complex at MI depth (could raise to surface level) • “Conventional” target+horn(single) + 5.8° bend + production straight (204m) • Bend: sign and momentum selection – With 2.4MW on target there is now ~ 145 kW in the beam • Production straight: transport of beam to end of decay straight. • ~110 kW pions + ~30 kW protons at beginning • ~35 kW + ~17 kW = ~42 kW at end & into absorber (+ ~25 kW in muon) July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 17
“ Waste power” mitigation • “Waste power” is kept at MI depth. – Less problematic than dealing with underground (cheaper) • Since no line-of-sight from target to production straight, unwanted charged particles and neutrons can be absorbed at/near surface level in the target hall complex. – Will show preliminary MARS results. – Power going underground limited to ~ 145 kW (2.4MW on target) 145 kW 2.4 MW 67 kW One concept for Primary absorber Absorber hall Plan (TOP) view schematic July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 18
nuPIL Current status • FFAG 5.8 o bend – Double achromat Bend: 4 FDF triplets (12 magnets) • 3 Quad match into beam line straight • Quad triplet (FDF) straight beam line • This is a hybrid system: FFAG - Quad Note: Aperture stops for wrong-sign π only introduced after magnets 11 & 12 at present July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 19
Beam propagation through the bend After horn After dispersion creator After bend cell 1 After bend cell 2 (end) At end of decay pipe π + decay off July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 20
ν production straight • The π decay beam line channel (production straight, formally known as a Decay Pipe) is a 200 meters long straight beam line consisting of a total of 27 quadrupole magnets. The first three quads match the optics after the FFAG steering bend to the periodic cell optics, which is defined by a triplet cell (FDF). G4Beamline visualization: Red vertical bands are quads July 21, 2016 Alan Bross | DUNE Accelerator and Beam Interface Group Meeting 21
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