Beamline for the LBNE Project Heidi Schellman for the LBNE collaboration

Baseline = 800 miles LBNE Experiment 20 miles underground Near Detector ICHEP2

Goals: Mass Hierarchy and CP violation NH A ~ pure ν μ beam generated by the ~120 GeV MI proton beam. Wide-band matched to the L/E for the first and second oscillation maxima for a 1300 km oscillation length. ≈ 780 ν e events Measure relative ν μ and ν e rates at Far Detector for neutrinos and anti-neutrinos ICHEP ≈ 7000 ν μ events 3

Top of band: Best case beam and interaction systematics (with near detector) Bottom of band: Worst case beam and interaction systematics (no near detector) Exposure: 34 kt x 1.2 MW x 6 years (half ν + anti-ν). MH and CP Sensitivities ICHEP4

Beam  Extract from Main Injector at GeV  5.8 degrees down  Go up first!  Plan for 1.2 MW beam power at start  Upgrade path to 2.3 MW  NUMI-like  ~1 m graphite target  2 Focusing horns  204 m Decay pipe ICHEP 5.8 degrees down Physics report LBNEarXiv:

Design challenges Maximize beam power at the right energies Cost optimization Radiological safety System reliability – Corrosion – Cooling – Radiation damage – Accessibility – Spares ICHEP6

Neutrino flux uncertainties Need to understand the beam parameters very well as physics results depend on ability to estimate the neutrino flux – Avoid multiple interactions in the target – Alignment tolerances – Spot size – Downstream material – Horn behavior Near detector helps a lot as much of this cancels in a near/far ratio ICHEP7

New since 2012 Conceptual Design Be ready for 1.2 MW on day one (previous talk by Steve Brice) Helium instead of air in the decay pipe to increase the neutrino flux and reduce the systematics Optimization studies for beam energy GeV ICHEP8

Target Hall/Decay Pipe Layout ICHEP Target Chase: 1.6 m/1.4 m wide, 24.3 m long Decay Pipe concrete shielding (5.5 m) Geomembrane barrier system to keep groundwater out of decay region, target chase and absorber hall Work Cell Baffle/Target Carrier 204 m 4 m helium-filled steel Cooling panels 9

Preliminary target design for 1.2 MW ICHEP mm Currently simulating this target design and the NuMI horns with MARS and GEANT. 47 graphite segments, each 2 cm long Graphite fin stress Water line stress 10

Preliminary target design for 1.2 MW Expect to change a graphite target ~2-3 times a year during 1.2 MW operation – Limited lifetime due to radiation damage to graphite and thermal stresses – Increase the beam rms of 1.7 mm and Increase the graphite fin size to 10 mm Considering as an alternative a Be target – Radiation damage a factor of 10 less than graphite (subject of R&D) ICHEP11

Horn Operation at 1.2MW ICHEP Parameters700 kW1.2 MW Current Pulse Width2.1ms0.8ms Cycle Time1.33s1.20s Horn Current230kA Target Width7.4mm10mm Protons Per Spill4.9 X X Beam heating and joule heating on horn 1 generate unacceptable power input into the horn inner conductor with the new target design and the NuMI horn power supply (2.1ms pulse width). Higher energy depositions from the target can be offset by reducing the current pulse width to 0.8ms (requires a new horn power supply). These changes allow the design current to remain at 230kA which is the upper current limit for a NuMI conductor design. Water Tank 12

 Decay pipe cooling air supply flows in four, 28-inch diam. pipes and the annular gap is the return path (purple flow path) (Helium increases the flux by ~10%) ICHEP  Concentric Decay Pipe. Both pipes are ½” thick carbon steel Decay pipe 13

LBNE Absorber Complex – Longitudinal Section ICHEP Decay Pipe The Absorber is designed for 2.3 MW A specially designed pile of aluminum, steel and concrete blocks, some of them water cooled which must contain the energy of the particles that exit the Decay Pipe. concrete CCSS Steel Al Steel Hadron Monitor (needs R&D ) Thermal, structural, mechanical engineering development in progress 14

LBNE Near Detector Fine-Grained Tracker – 460 m from target Low-mass straw-tube tracker with pressurized gaseous argon target Relative/absolute flux measurements High precision neutrino interaction studies ≈ 10 7 interactions/year! Additional target materials possible Proposal pending in India ICHEP Dr. Zelimir DJURCIC at 1630 today in the Neutrino section 15

Physics optimization studies Use G4LBNE – GEANT4 simulation based on G4NUMI LBNE Fast MC for detector efficiency/purity – GENIE event simulation – Parameterized detector response ICHEP Target Horns 16

Beamline contributions to absolute flux ICHEP Predicted absolute flux errors at the near detector vs. energy 17

Errors on Near/Far ratio ICHEP18

Mostly cancel in a near/far ratio ICHEP 0.5 mm alignment tolerances lead to error on Near/Far ratios << statistics Near to far ratio is less sensitive 19

Signal rates at different proton energies ICHEP Estimated  e rates for baseline MW beam power, 35 kT detector Feed-down source Signal region Events/ GeV Integrated difference in figure of merit S/√S+B between between 120 and 80 GeV is +8% for, +16% for ν̄ 20

Helium vs. Air ICHEP Study for neutrino beam mode – LBNE doc: 8144 He yields 11% more flux GeV 4% less anti-nu background GeV 21

Potential optimizations ICHEP Change GeV GeVComment DK pipe Air  He * DK pipe length 200 m  250 m (4m D) $ DK pipe diameter 4 m  6 m (200m L) $ Horn current 200 kA  230 kA Proton beam energy 120->80 GeV Target graphite fins  Be fins Increase target lifetime Total~1.4~ 1.5 Ratio of   e CC appearance rates at the far detector Simplifies the handling of systematics as well Recently approved Subject of R&D 22

From the P5 report Timeline ICHEP23

Conclusions Significant progress with preliminary design effort in many Beamline systems. Robust simulation framework is aiding physics and value optimization Lots of opportunities for collaboration on Beamline components as well as on beam simulations and R&D efforts. ICHEP24

Beam simulations Primary beam magnet and power supply design and construction Primary and neutrino beamline instrumentation Target R&D Target, Baffle and Horn support modules Horn R&D for 2nd generation 1.2 and 2.3 MW Design and construction of cooling panels for the target chase shield pile Upstream decay pipe window Corrosion studies for target chase, decay pipe and absorber Radiation simulation verification – simulate known irradiations at known facilities and compare with actual measurements Hadron production studies that provide essential input for the prediction of the neutrino flux. And many more….. Design Opportunities ICHEP 25

BACKUP ICHEP26

Beam design parameters ICHEP The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe arXiv:

Parameters cont. ICHEP28

Proton Improvement Plan-II Performance Goals ICHEP - 80 GeV PIP-II doc: 1232 S. Holmes et al. 29

Replace existing 400 MeV linac with a new 800 MeV superconducting Linac 1.2 MW beam power to LBNE at start-up of experiment. Plan is based on well-developed superconducting RF technology. Strong support from DOE and in the recent Prioritization Panel report. Flexible design - future upgrades could provide > 2MW to LBNE. Proton-Improvement-Plan Phase II (PIP-II) ICHEP Steve Brice Talk 30

R&D needs At 1.2 MW R&D will be needed on: – target (materials) assuming minimal modifications will work – horns (2 nd generation) assuming minimal modifications will work – hadron monitor At 2.3 MW additional R&D will be needed on: – target (materials, shape, cooling,…) – horns – hadron monitor – primary beam window (only cooling aspects affected by 1.2 MW) ICHEP31