A pion beam line option for LBNF – nuPIL Moving beyond Simon van der Meer’s Paradigm？ Alan Bross

Outline Introduction Design overview Neutrino flux comparison Physics comparison August 25, 2016

Credits Jean-Baptiste Lagrange Jaroslaw Pasternak Imperial College London AB Pilar Coloma Ao Liu David Neuffer Hannah Mularczyk (Target student) Milorad Popovic (working on independent concept) Fermilab Terry Hart University of Mississippi Elizabeth Worcester BNL August 25, 2016

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 5.8o bend matched into a straight transport beam line (~200m) Basic design evolved from the pion injection beam line for nuSTORM. August 25, 2016

Pion Instrumented Line (nuPIL) nuSTORM Pion Instrumented Line (nuPIL) David Neuffer, Ao Liu X Kill the STORM part Eliminate m storage capability X X X 1300 km 2 km Target Station Ao Liu, JB Lagrange Residual high energy protons bend down 2.9° π decay in the straight August 25, 2016

nuPIL advantages I Beam systematics Beam systematics concerns for conventional horn-focused n 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 n background in the anti-n beam (& vice versa) is significantly reduced August 25, 2016

Beam systematics II Diagnostics Instrumentation for the beam line Quantity Detector(s) Comments Beam Intensity Beam current transformers <1% resolution obtainable Beam Position BPMs 1 cm resolution Beam profile Scintillating screens, etc Destructive Energy spread Profile measurement in bend Beam loss Conventional Timing Pion/proton separation nuSTORM study Beam can be fully characterized, including destructive methods during a commissioning phase Magnet currents can be monitored and controlled with precision all magnets are DC Parameter Uncertainty Intensity 0.3% Divergence 0.6% Energy spread 0.1% Total ≤ 1% August 25, 2016

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

6 Quad match into beam line straight nuPIL Current status FFAG 5.8o bend Double achromat Bend: 4 FDF triplets (12 magnets) 6 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 p only introduced after magnets 11 & 12 at present August 25, 2016

Beam propagation through the bend After horn After dispersion creator After bend cell 1 After bend cell 2 (end) At end of decay pipe p+ decay off August 25, 2016

n production straight The p 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 six 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 August 25, 2016

nuPIL Lattice13-Hybrid vs. LBNF/DUNE 3-Horn Opt August 25, 2016

Sum(nuPIL nm flux)/Sum(3-horn flux)= 0.54 August 25, 2016

ne and anti-nm background in nm beam Ratio of LBNF to nuPIL normalized to number of nm Backgrounds significantly lower in nuPIL August 25, 2016

CP violation sensitivity from Elizabeth W. Sensitivity calculations produced by Elizabeth Worcester Flux for LBNF beams produced by Laura Fields Flux for nuPIL beam provided by Ao Liu Unless otherwise noted, all configurations (GLoBES code, oscillation parameters, systematic selection efficiencies, etc) are identical to those used in the CDR LBNF optimized: identical to “optimized design” in CDR, but with 204 m DP LBNF 3-horn optimized: updated LBNF optimized design with improvements including, but not limited to moving to 3-horn design. August 25, 2016

3s coverage over 75% of d range (Pilar Coloma) 3.5 + 3.5 years August 25, 2016

One more comment on Flux

nuPIL flux at Near Detector L= 250m from bend Note: ne flux ~ nuSTORM August 25, 2016

Basic physics requirements ~ met, but not better than LBNF baseline For CP 3s sensitivity over 75% of the dCP range with an 850 kt*MW*yr exposure. Resolution on dCP of better than 20 degrees. Precision measurement of all oscillation parameters including q13. However: ½ pion power “wasted” in the straight Matching: bend-straight Horn efficiency low Some gain might be achieved with further horn optimization August 25, 2016

Beam power loss in straight August 25, 2016

Pion beam power Red: momentum distribution for pions transported full length of straight Blue: momentum distribution for pions lost in straight August 25, 2016

Current power loss with aperture stops in matching section August 25, 2016

Horn efficiency 80 GeV protons on C Green: All p+ off target Blue: p+ into acceptance At P0 (5 GeV/c) ~< 50% Horn: ~70% August 25, 2016

Conclusion Using a pion beam line after a high-power target/horn module presents an exciting possibility for producing a nm beam for long-baseline n oscillation experiments Comparable physics performance. Potential for increasing flux Much higher beam quality w/r to beam purity Beam systematics uncertainties reduced Neutrino beam flux determined directly from parent particles, not induced from other experiments or MC. Uncertainties reduced by possibly a large factor due to the beam line instrumentation Underground radiological issues essentially removed At this stage of the analysis, the nuPIL concept is cost neutral July 21, 2016

Conclusions II However at this time nuPIL would have to: “Given the status of nuPIL and the many constraints on the LBNF project, LBNF management sees the LBNF baseline (3-horn) the only viable way forward.” nuPIL would have to: Fix match, hadron loss in straight Improve flux (# n) Demonstrate via detailed and exhaustive MC, the the projected flux error precision that would come from the instrumentation in the straight Demonstrate a high-energy tune for nt physics August 25, 2016

Thank you

Backup

High E tune example August 25, 2016

nm flux: Lattice13 extrapolated to P0=7.5 GeV/c August 25, 2016

Engineering considerations The nuPIL configuration does add active components in the target station. Can they survive? A MARS simulation of a “parameterized” TS has been performed. Magnets simulated with cylindrical symmetry with 80 cm bore and 1m Fe annulus outside bore as return yoke. Uniform (dipole) magnetic filed in bore August 25, 2016

Target station design The baseline design for LBNF follows the design for NuMI To a large extend, it is the NuMI TS at surface This configuration does not accommodate the nuPIL components very easily TS design the NF Study 1 ORNL/TM-2001/124 “Support Facility for a Mercury-Jet Target Neutrino Factory”, September, 2001. August 25, 2016

nuPIL TS MARS simulation Model Grey: concrete Red: steel Blue: dirt White: vacuum August 25, 2016

nuPIL TS MARS simulation >5 GeV/c tracks Straightforward to deal with residual proton beam at surface August 25, 2016

nuPIL TS MARS simulation Energy deposition Reduction in Edep - first magnet to last: 104 to 105 August 25, 2016

August 25, 2016

NF TS Design August 25, 2016

NF TS Design II August 25, 2016

NF TS Design III August 25, 2016

NF TS Design IV August 25, 2016

LBNF ne spectra August 25, 2016

Signal/Bkg (PC) nuPIL DUNE August 25th, 2016