Overview of MiniBooNE Ray Stefanski Fermilab August 29, 2010 An - PowerPoint PPT Presentation

Overview of MiniBooNE Ray Stefanski Fermilab August 29, 2010 An overview of backgrounds & systematic effects; concentrating on interaction cross-section measurements Rough Outline a.) detector configuration b.)sources of systematic uncertainty b1.) flux b2.) x-sections b3.) reconstruction c.) MiniBooNE measurement d.) future 7th International Workshop on Neutrino Beams and Instrumentation

M’BooNE Schematic Geometry The detector is a sphere of radius; 610.6 cm located from target; 541m filled with of Marcol7 CH . 800 T 2 Beryllium target ~ 4 10 10 12 12 ppp @ 15Hz slugs each 7 An inner opaque shell of radius , is 575 cm 5 pulses per second radius 0.48 cm concentric with the sphere and is 121 10 10 - 17 17 ν per POT 10.2 cm long instrument ed with an array of , 8" PMTs μ 1280 1.7 λ 22 22 10 10 - 17 17 ν totals per POT facing inward; and an array of PMTs in 240 interactio n μ the outer veto region. 25 m absorber Collimatio n SciBooNE n - - . 1.47 0.68 threshold ~100m from target 3 . 0.86 g/cm Decay region : long 50 m 8 GeV beamline Focussing magnetic radius 90 cm horn : . 170 kA @ 15 Hz filled with air. L/E ~1, similar to LSND Designed for 5 pulses/s. 7th International Workshop on Neutrino August 29, 2010 2 Beams and Instrumentation

What constitutes an “event” in M’BooNE The ~1 GeV beam at M’BooNE results in interactions that are relatively low in outgoing multiplicity. The largest interaction channel is the l CCQE process l +n -> l + p, which accounts for ~40% of all the interactions in the M’BooNE detector. Since the recoil proton is typically below threshold, only the outgoing 0 for NC interactions, produces significant light. lepton, or While the recoiling nucleon can produce significant scintillation light, this additional source of light is not considered in the reconstruction. 7th International Workshop on Neutrino August 29, 2010 3 Beams and Instrumentation

What constitutes an “event” in M’BooNE If we define a “hit” as a PMT with a signal above threshold, then we eliminate many backgrounds with a simple set of cuts. 7th International Workshop on Neutrino August 29, 2010 4 Beams and Instrumentation

What constitutes an “event” in M’BooNE • PMT hits separated into time clusters An event display: • Reconstruct Cherenkov rings and arrange in time. • each bubble represents a PMT “hit”; CCQE events must contain 1 & only 1 subevent. • charge -> bubble size; • time -> color; CCQE events with 5.58 X 10 20 POT 146,070 • range is early; efficiency = 27% blue comes later. purity = 77 % time cluster  e e event 1 ST 2nd subevent subevent e 7th International Workshop on Neutrino August 29, 2010 5 Beams and Instrumentation

Understanding the detector: response of the oil to Creation Run time measuremen ts A1. Cherenkov light Michel electrons A1; A2; B2 dependence Cosmic muons A1; A2; B2 A2. Scintillat ion Diffuse laser light B1 ; B2 a. dE/dx Pencil beam laser B 1; B2 b. temperal response Propagati on Measuremen t of the properties of the oil. B1. Scattering (Rayleigh) Scintillat ion (IUCF) w/p A2 a. temperal response (prompt) Scintillat ion (Fermiloab ) w/ A2 2 b. 1 cos repeated w/p (IUCF) 4 Goniometry (Princeton ) B1; B4 c. dependence Fluoresce nce spectrosco py (Fermilab) B2 B2. Fluorecse nce Temperal spectrosco py (JHU) B2 a. isotropy Attenuatio n (Fermilab) B1; B2; B3 b. temperal response multiple devices c. dependence B3. Absorption 7th International Workshop on Neutrino August 29, 2010 6 Beams and Instrumentation

Understanding the detector: Energy dependence 7th International Workshop on Neutrino August 29, 2010 7 Beams and Instrumentation

Understanding the detector: Flux uncertainties – particle production Horn in mode. Geant4 - based neutrino flux simulation . These are the M' BooNE From CCQE interactio ns, measured flux published production exceeds prediction by 1.21 0.24 uncertaint ies based on a 9 Simulation includes tertiary interactio ns in parameter fit of the Sanford - target area and decay volu me. Wang formula to the HARP measuremen ts, extented to Horn in mode. account for thick target effects. In practice, flux error Horn in mode. uncertaint ies are derived from a spline fit to the HARP data, which result in a ~ 9% error at From CCQE interactio ns, measured flux roughly equals predicted flux. the peak flux at ~ 800 MeV energy. The complete error matrix is calculated in bins of Horn in mode. energy and include correlatio ns between bins. 7th International Workshop on Neutrino August 29, 2010 8 Beams and Instrumentation

Understanding the detector: Flux uncertainties – beam properties + due to Change in flux from dominant sources of systematic uncertainty: horn current; n-N qe x-sect.; + -N qe x-sect.. decreased & increased skin effect Horn in mode. (a) Predicted flux at the M' BooNE detector. (b) Fractiona l uncertaint ies grouped Horn in mode. into various contributi ons. The integrated flux is - 10 2 5.15 10 /POT/cm ( 0 3 GeV) E with mean energy of 788 MeV. 7th International Workshop on Neutrino August 29, 2010 9 Beams and Instrumentation

Understanding the detector: cross-sections – NUANCE Predictions from the NUANCE event generator for fractional Variables extracted from the track reconstruc tion assumin a hypothesis . occurrence of interactions in neutrino mode. Resonant T muon kinetic energy and coherent processes are included. muon scatter5in g angle. Additional reported observable s are : E T m the total muon energy ' ' 2 2 2 2 ( M ) E (( M ) m M ) QE n n p E , ' 2 2 2 [( M ) E E m cos ] n 2 2 QE 2 2 Q m _ 2 E ( E E m cos ), QE where M , M , and m are the neutron, n p proton and muon masses. ' M M E , where E is the separation Constants used in NUANCE models : B B n n energy in carbon and is set to 34 9 MeV. QE M 1 . 35 0 . 17 ; axial mass for QE and NC EL events A 34 MeV 9MeV; binding energy in Fermi gas model E B A similar set of relations is used for electrons p 220 MeV/c 30 MeV; Fermi momentum in Fermi gas model F and photons. 0 0.10; strange contributi on to proton spin s MA 1 . 1 GeV 0.275 GeV; axial mass in resonant 1 production mode 1 MA 1 . 3 GeV 0.52 GeV; axial mass in N and non - pion production mode N 0 cog 1; NC coherent cross - section delrad 1.022 .1245; radiative ( ) BF and FSI. N dis 1 0.25; DIS cross - section - - not well known at MiniBoo NE energies. kappa 1.007 0.012; Pauli blocking scale factor macoh 1 . 03 GeV 0.275; axial mass in NC, CC coherent pion production x - sections. 0 RES pi0 0.947; NC resonant cross section H MA 1 . 13 0 . 10 ; axial mass for QE and NC EL interactio ns on H QE 2 Nubar 1.0 0 . 10 ; cross - section normalizat ion uncertaint y for scattering 7th International Workshop on Neutrino August 29, 2010 10 Beams and Instrumentation

Understanding the detector: event reconstruction In the track based reconstruction, four signal patterns are used: 1. single electron track, 2. single muon track, 3. two tracks, 0 invariant mass. 4. and two tracks with a The CH 2 has and extinction length of ~20m, the radiation length is ~50cm, and exhibits a wide range of optical phenomena near the peak of the PMT sensitivity: 400 nm. Cherenkov light and scintillation light are accompanied by 1. photon absorption; 2. fluorescence; ( with several excitation/emission spectra and lifetimes) 3. Rayleigh scattering; 4. and Raman scattering. Also, photon reflection from the surface of the tubes, and the surface of the main detector region must be considered in the simulations. The electronics dead time is ~ 300 ns. A Geant3-based Monte Carlo simulation serves as the main tool for developing reconstruction algorithm’s predictive models. 7th International Workshop on Neutrino August 29, 2010 11 Beams and Instrumentation

Understanding the detector: event reconstruction The quantities measured by the detector are: the number of PMTs that have recorded a light pulse – “hits” – the charge recorded on each PMT; and the time of the hit. From these measured quantities , a vector w ith seven variables , , x is produced : The starting point : x , y , z ; 0 0 0 The starting time : t ; 0 the direction : , ; 0 0 The kinetic energy : E . 0 In simulation, the flux, cross-section model (NUANCE), and detedtor characteristics are combined to convert an event type as input to generation of a set of PMT hits with associated time and charge. The simulation and data are passed through the same reconstruction routines to generate x , which is used to test our ability to reproduced the data in simulation. 7th International Workshop on Neutrino August 29, 2010 12 Beams and Instrumentation