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SNS Spallation Neutrino Source

SNS Spallation Neutrino Source. SNS layout. Stripping foil. 1.0 GeV proton linear accelerator. Accumulator ring. Main target. SNS Parameters. Proton beam energy – 1.0  - 1.4 GeV Intensity - 9.6  10 15 protons/sec Pulse duration - 380ns(FWHM) Repetition rate - 60Hz

honorato-joyner
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SNS Spallation Neutrino Source

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  1. SNSSpallation Neutrino Source

  2. SNS layout Stripping foil 1.0 GeV proton linear accelerator Accumulator ring Main target

  3. SNS Parameters Proton beam energy – 1.0 - 1.4 GeV Intensity - 9.6  1015 protons/sec Pulse duration - 380ns(FWHM) Repetition rate - 60Hz Total power – 1.0 3 MW Liquid Mercury target

  4. ~ 60 m Target building Proton Beam

  5. 21 cm Mercury target Mercury Inventory – 20 t Flow rate 340 kg/sec Vmax 3.5 m/sec Tin 600C Tout 900C Mercury lasts the entire 40 year lifetime of SNS no change is required Stainless steel vessel should be replaced periodically

  6. Some Details of Interaction in the Target Average interaction energy is ~1.1 GeV Average interaction depth ~11 cm Proton interacts near the front part of the target

  7. DIF vs. DAR Pion Spectra 200 MeV/c pions range in mercury is ~ 5 cm Very few pions have a chance to decay before coming to the rest Because of the bulk Mercury target, SNS is a Decay At Rest facility !!

  8.   + + Hg e+ 0.13 e 0.09 p - 99.6% SNS Capture ISIS, LANSCE Neutrino Production 1.3 GeV At the first approximation: N +/proton = 0.14*E(GeV)-0.05 For E~0.8-1.5 GeV

  9. Neutrino spectra well defined in SM e and are in the different time intervals Actual spectra of neutrinos from SNS Energy Time

  10. Neutrino Rates Number of protons on the target for 1.1 mAat 1.3 GeV is 0.687·1016 sec-1 Number of each flavor neutrino produced by one proton is 0.13 SNS live time is 2/3 of the year Number of each flavor of neutrinos produced at SNS is 1.9·1022 year-1 Caveat: There is larger flux of antineutrinos from decay of radioactivity in the target However, heir energy is a few MeV and almost continues in time. We did a few attempted to calculate those, but all grad students failed to deliver robust result. It would be nice to finish this....

  11. Cross Sections Integrated over SNS spectra. Reaction ee-ee- e-e- e12C 12Ngs e- e12C e 12C* 12C 12C* e56Fe 56Co e- Integrated Cross Section 0.29710-43 cm2 0.05010-43 cm2 0.9210-41 cm2 0.4510-41 cm2 0.2710-41 cm2 ~2.510-40 cm2 SNS delivers ~ 1.9·1022 neutrinos per year

  12. KARMEN LSND Necessary detector mass

  13. SNS Beam Info Mode: TargetPower on Target: 1003.24 kWCharge to Target: 18.5E-6 CProton Energy: 910.0 MeVRing Frequency: 1.041 MHzBeam Rate: 59.9 HzMPS Mode: 1 mSec SNS status

  14. SNS Status Long Term

  15. SNS Calendar

  16. Lets assume shielded bunker with area of 25 m2 on the surface Cosmic rays BG estimation SNS duty factor is 410-4 This effectively reduce flux to 105 muons and ~600 neutrons per day entering enclosure We need one meter of steel overburden to reduce hadronic component of atmospheric showers and hermetic veto with efficiency of 99% Our estimations shows that expected number of untagged neutrons events in the detector is a few per day. This is below expected neutrino event rates Extra factor can be expected from PID in detectors.

  17. We considered three major sources: 1.7 m 6.3 m Space Allocated For Neutrinos 1.7 m From the neutron instruments Target Monolith 18.3 m Target 4 m Proton Beam From the tunnel SNS induced BG Most dangerous B.G. is from SNS neutrons Analysis is complicated because many uncertainties still exist. We know for sure that environment is OK for humans. However neutrinos detectors are much more sensitive then humans!

  18. Target Neutrons Full 3D MSNPX calculations were performed till ~2 m Coupling tool MTD was used to couple to 2D DORT code to propagate further. Instrumental floor was modeled up to distance of 30 m

  19. Neutrons from the Target

  20. Neutrons from the Tunnel Similar Calculations were done taking into account beam losses Beam losses ~ 1W/m (Linear source)

  21. Neutrons from the Tunnel

  22. SNS induced neutron fluxat 20 meters High energy neutrons can be eliminated using time cut To reduce low energy neutrons (neutron gas), extra shielding and neutron absorbers are required • Just moving out without erecting extra shielding: • Front side (target) 1/R2 • Right side (instruments) required detailed study • Left side (tunnel) 1/R

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