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

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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

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

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

14. 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

15. 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

16. 3s coverage over 75% of d range (Pilar Coloma)
years
August 25, 2016

17. One more comment on Flux

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

19. 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

20. Beam power loss in straight
August 25, 2016

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

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

23. 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

24. 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

25. 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

26. Thank you

27. Backup

28. High E tune example
August 25, 2016

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

30. 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

31. 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

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

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

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

35. August 25, 2016

36. NF TS Design
August 25, 2016

37. NF TS Design II
August 25, 2016

38. NF TS Design III
August 25, 2016

39. NF TS Design IV
August 25, 2016

40. LBNF ne spectra
August 25, 2016

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