1. Robert Cooper L. Garrison, L. Rebenitsch, R. Tayloe, R. Thornton

2. Fermilab Measurement Sites MINOS Near NuMI Target BNB Target 10/11 – 2/12 2/12– 5/12 2R. Cooper, APS DNP 2012, Newport Beach, CA

3. Motivation and Goals NuMI @ MINOS Near 100 m underground backgrounds: n,  Beam correlated events: n, , Support 0 2  & dark matter experiments *Mei & Hime, Phys. Rev. D 73 053004 (2006)) 3R. Cooper, APS DNP 2012, Newport Beach, CA

4. Motivation and Goals Beam correlated neutron background Support far off-axis low-E source Coherent Elastic - Nuclei Scattering on LAr BNB @ MI-12 4R. Cooper, APS DNP 2012, Newport Beach, CA Images courtesy J. Yoo

5. NuMI Underground Site 100 m overburden 5 mrad off-axis Oct. 7 – Dec. 19 6.41x10 19 total POT Expect 800 cosmic neutrons (20 / day) Expect 65 CCQE (350 CC-Inclusive) 5R. Cooper, APS DNP 2012, Newport Beach, CA

6. MI-12 Neutron Background Run Neutron flux ~18 m from target In-line behind beam target (ground) 29 Feb. – 23 Apr. 8 GeV protons 7.8M beam pulses (5x10 12 POT / pulse) 6R. Cooper, APS DNP 2012, Newport Beach, CA

7. MI-12 Neutron Background Run Neutron flux ~18 m from target In-line behind beam target (ground) 29 Feb. – 23 Apr. 8 GeV protons 7.8M beam pulses (5x10 12 POT / pulse) 7R. Cooper, APS DNP 2012, Newport Beach, CA

8. SciBath Concept Bath of liquid scintillator (45 cm) 3 length cubic volume 3D array, crossed wave- length shifting fiber readout 768-channel with 64-anode PMT system (x12) Indiana university custom- built DAQ ($70 / ch w. PMT) 8R. Cooper, APS DNP 2012, Newport Beach, CA

9. The SciBath-768 Detector 80 L liquid scintillator (LS) 88% mineral oil 11% pseudocumene 1% PPO 768 (3-16x16) array wavelength-shifting fibers (x,y,z axes) 1.5 mm diameter 2.5 cm spacing UV → blue 9R. Cooper, APS DNP 2012, Newport Beach, CA

10. NuMI Beam Time Structure muons - n /  PID n Pri high-E (non-  ) events n Cap could be low-E n or non- capture  Exponential life- time n-capture 10R. Cooper, APS DNP 2012, Newport Beach, CA

11. NuMI Cosmic Neutron Energy Preliminary High PE primary  rejected w. PID Require n-capture secondary 721 n consistent with prediction (800)  -tagged neutron spectrum at 100 m Preliminary 11R. Cooper, APS DNP 2012, Newport Beach, CA

12. MI-12 Beam Time Structure Neutron capture time for low PE events Neutrons scattering in short time scale? 12R. Cooper, APS DNP 2012, Newport Beach, CA

13. MI-12 Neutron Energy Spectrum 2.5 n per pulse (energy > 40 MeV) Protons > 200 MeV do not “range out” Background to CENNS experiment Neutron spectrum 20 m from BNB Best Fit Neutron Spectrum 13R. Cooper, APS DNP 2012, Newport Beach, CA Preliminary

14. Summary Cosmic neutron energy spectra at NuMI  Dark Matter & 0 2  BNB neutrons rate within expectations  Coherent -N Coming to a facility near you? 14R. Cooper, APS DNP 2012, Newport Beach, CA Preliminary

15. Summary Cosmic neutron energy spectra at NuMI  Dark Matter & 0 2  BNB neutrons rate within expectations  Coherent -N Coming to a facility near you? 15R. Cooper, APS DNP 2012, Newport Beach, CA Preliminary

16. Summary Cosmic neutron energy spectra at NuMI  Dark Matter & 0 2  BNB neutrons rate within expectations  Coherent -N Coming to a facility near you? 16R. Cooper, APS DNP 2012, Newport Beach, CA

17. BACKUP SLIDES 17R. Cooper, APS DNP 2012, Newport Beach, CA

18. NuMI Beam Muon Spectrum 18R. Cooper, APS DNP 2012, Newport Beach, CA

19. n /  Particle Discrimination 19R. Cooper, APS DNP 2012, Newport Beach, CA

20. n /  Particle Discrimination “muons” 20R. Cooper, APS DNP 2012, Newport Beach, CA

21. n /  Particle Discrimination neutrons 21R. Cooper, APS DNP 2012, Newport Beach, CA

22. Sample Event 22R. Cooper, APS DNP 2012, Newport Beach, CA

23. Neutron Sensitivity (w. n-capture) 23R. Cooper, APS DNP 2012, Newport Beach, CA