NuMI MINOS The MINOS Far Detector Cosmic Rays and their neutrinos are being collected now. How does this work, and of what use is this data? Alec Habig, Univ. of Minnesota Duluth, for the MINOS collaboration

NuMI MINOS Neutrino 2002, May 25-30, 2002, Munich Alec Habig Page 2 The MINOS Experiment Main Injector Neutrino Oscillation Search –Will utilize NuMI beam from Fermilab Front-to-back  oscillation study –Produce well-studied  beam –Measure  spectrum just after production with “Near Detector” –Measure again 735 km later with “Far Detector” Beam goes from Fermilab to the Soudan Mine Underground Lab 735 km

NuMI MINOS Neutrino 2002, May 25-30, 2002, Munich Alec Habig Page 3 The Far Detector Steel/Scintillator sampling calorimeter –5.4 kt, 8m diameter, 31m long –486 layers, each made of: 1” steel 1 cm plastic scintillator –Magnetized to ~1.5 T Design goals – e /  /  discrimination –Good energy resolution For both  and showers –Good timing, both hit-to-hit and absolute For particle direction and synching with Fermilab beam ½ of the Far Detector To FermilabTo Fermilab 15m 8m

NuMI MINOS Neutrino 2002, May 25-30, 2002, Munich Alec Habig Page 4 Far Detector Progress Construction began August 2001 Now up to about plane #225 –Almost halfway done! –First half complete in July when it will be magnetized Taking Cosmic Ray data as it is built –Each plane independently instrumented Plane #200, May 3, 2002

NuMI MINOS Neutrino 2002, May 25-30, 2002, Munich Alec Habig Page 5 Particle Detection 4.1 cm x 8m scint strips bundled into “modules” –Light channeled out via 2- ended fiber Each plane’s strips are 90 o from the last –“U” and “V” views 17 GeV MC  shown below from side, in U,V From FNAL

NuMI MINOS Neutrino 2002, May 25-30, 2002, Munich Alec Habig Page 6 Multiplexing Light detected by 16 pixel PMTs 8 fibers per pixel, ganged together with: –Maximal physical strip separation –Minimal in-PMT cross- talk M16 PMT 16 mm Fiber Layout One of 3 Ham. M16 PMTs in this “Mux Box”

NuMI MINOS Neutrino 2002, May 25-30, 2002, Munich Alec Habig Page 7 Front End Electronics Fibers from each strip end are multiplexed onto PMT pixels Signals amplified, shaped, and tracked+held by “VA” chips –Calibration charge can also be injected in the same place as PMT charge for functionality check and calibration of full electronics path Timing information sent upstream from this “Front End” rack

NuMI MINOS Neutrino 2002, May 25-30, 2002, Munich Alec Habig Page 8 Data Gathering VME “Master” crate –VA Readout Controllers “VARC”s Charge from PMTs digitized by 14-bit ADCs Time stamped to 1.6ns by internal clock –2/6 or 2/36 pre-trigger applied –Hits given absolute GPS time Data read out over PVIC bus to computer room –4/5 plane software trigger applied, hits time ordered –Data formatted in ROOT 1 of 16 VME crates Digitizes 72 mux boxes Each w/3 16-pixel PMTs

NuMI MINOS Neutrino 2002, May 25-30, 2002, Munich Alec Habig Page 9 De-multiplexing Scintillator strip ends are multiplexed 8-1 per electronics channel How to figure out which strip a particle really went through? Matching hits on both ends of a strip helps in the simplest track case For multiple hits on a plane and showers: –All the different possible “hypotheses” of which strip was really hit tested against the possible real physics –Best fitting hypotheses saved Reconstructing close multiple muons very difficult!

NuMI MINOS Neutrino 2002, May 25-30, 2002, Munich Alec Habig Page 10 A Cosmic Ray De-multiplexed Success rate for Cosmic Rays: –94% of hits correctly associated with their strips –97% of CR events successfully sorted out CR  before De-multiplexing CR  after De-multiplexing

NuMI MINOS Neutrino 2002, May 25-30, 2002, Munich Alec Habig Page 11 Light Injection Calibration using controlled light: –LEDs illuminate 8-10 calibration fiber ends each –Fibers carry light from LED to shine on ends of scint strip fibers Varying light levels used to map out detector and phototube response Regular pulsing at a constant light level during normal operations –Tracks changing detector response –Flags problems with optical path Light from calibration fibers illuminating ends of fibers from the scintillator where they are bundled

NuMI MINOS Neutrino 2002, May 25-30, 2002, Munich Alec Habig Page 12 Cosmic Rays CR-  light output with expectations ~10 pe at mid-strip (sum of both ends) As planes are added to the detector, they contribute to the data acquisition Currently taking Cosmic Ray data –CR rate: 1000  /strip/month, 2% stop in detector Excellent “beam” for detector commissioning –Real particle data provide end- to-end test of all hardware, software systems Good calibration source –Geometry, gain, timing, reconstruction software

NuMI MINOS Neutrino 2002, May 25-30, 2002, Munich Alec Habig Page 13 CR Calibrations Physical plane locations are surveyed as the planes are raised –CR  draw nice straight lines –Residuals to the  fits are not bad with nominal plane geometry, excellent with survey-corrected data Timing calibrations –CR  are nice straight lines moving at  =1 –Use this physics to find and fit absolute timing offsets Need t0 fit plot Timing offsets (ns) vs. channel. Different delays in different electronics paths are clearly seen, as is the few (2.6) nanosecond resolution

NuMI MINOS Neutrino 2002, May 25-30, 2002, Munich Alec Habig Page 14 Initial Searches Atmospheric are present in the data –Contained vertex search being refined –Up-going  search underway as part of CR timing calibrations Reconstruct timing of  tracks –Down-going CR’s have  =1 –Up-going -induced  have  =-1 An up-  !

NuMI MINOS Neutrino 2002, May 25-30, 2002, Munich Alec Habig Page 15 Summary First ! An up-going  seen on the evening of March 22, 2002 – MINOS works! The MINOS Far Detector construction is nearing the ½ way point Data being taken as the detector grows is used to validate and calibrate both hardware and software Will be ready for beam –Plus atmospheric work can be done with magnetic field! / separation The presenter gratefully acknowledges support for this poster from the National Science Foundation via its RUI grant #