Kevin McFarland, “  and , oh my” 1 5 July 2002 The Delicate Minutia of Fluxes, Neutrino Cross-Sections, and Detectors Near and Far: Kevin McFarland University of Rochester 5 July 2002 For Working Groups 2 and 3 A Global Perspective

5 July 2002 Kevin McFarland, “  and , oh my” 2 Outline Why is this important? Why is this important? –Short-term expediency –Grand Goals The bad news The bad news –The sub-few GeV region isn’t so easy! –Cross-sections, detector effects The good news The good news –Pioneers blazing the trail –Great toolbox: detectors, models

5 July 2002 Kevin McFarland, “  and , oh my” 3 The Importance of Superbeams Low-energy beams are in our future Low-energy beams are in our future –BooNE (Coney) –NUMI beam: LE, ME off-axis (Szleper) On-Axis Off-Axis

5 July 2002 Kevin McFarland, “  and , oh my” 4 Importance of Superbeams (cont’d) –JHF (Kajita) Number of events /100MeV/yr Eν(GeV) Max. osc. Background

5 July 2002 Kevin McFarland, “  and , oh my” 5 What Role do Low Energy Beams Play in The Long-Term Future? Show non-zero U e3 Show non-zero U e3 Measure  m 2 23 Measure  m 2 23 Resolve Degeneracies Resolve Degeneracies –Even with a neutrino factory, archival superbeam measurements are key! (Minakata, Whisnant, Mena, Huber) P(osc) vs E

5 July 2002 Kevin McFarland, “  and , oh my” 6 The Landscape of Superbeams Can’t support L too large Can’t support L too large –Limited proton power –No acceleration of neutrino source (à la  ) Small L/E makes no sense Small L/E makes no sense –Destroys degeneracy lifting property –Backgrounds are too large to reduce P(osc) E.g., e background is “naturally” ~1%; clever design can reduce this x2 or maybe x5… E.g., e background is “naturally” ~1%; clever design can reduce this x2 or maybe x5… So E is going to be sub-GeV to few-GeV So E is going to be sub-GeV to few-GeV

5 July 2002 Kevin McFarland, “  and , oh my” 7 And what’s so bad about that? E ~m target (Casper, Bodek) E ~m target (Casper, Bodek) –Massless quark DIS isn’t a good model –Have to deal with discrete final state mass –Center of mass not ultra-relativistic Final state particles in every direction! Final state particles in every direction! Current data at low E stinks Current data at low E stinks –Who would work here if they had a choice?

5 July 2002 Kevin McFarland, “  and , oh my” 8 State of the art at low E State of the art at low E n  – p  0 n  – n  + p  – p  + Data at first resonance (Casper) Data at first resonance (Casper) –20-50% uncertainties are par for course –Relevant? >50% of K2K far spectrum sample is inelastic…

5 July 2002 Kevin McFarland, “  and , oh my” 9 Can DIS describe resonances? Transition between resonance/DIS a “twilight zone” for cross-sections Transition between resonance/DIS a “twilight zone” for cross-sections –Enter duality! (Bodek) “If you get near a resonance, it just sucks you in!” “If you get near a resonance, it just sucks you in!” Can model resonances using DIS cross-sections with appropriate scaling Can model resonances using DIS cross-sections with appropriate scaling –Predictive approach –Should give a baseline to measure (nuclear) deviations

5 July 2002 Kevin McFarland, “  and , oh my” 10 Nuclear Cross-Section Effects Couple detector and cross-section Couple detector and cross-section Many inaccurately modeled effects (Casper) Many inaccurately modeled effects (Casper) –E.g., quasi-elastic case, which is a calculable cross-section, m A =1.01±0.02 GeV –Nuclear effects introduce uncertainties Fermi motion, binding energy, Pauli blocking Fermi motion, binding energy, Pauli blocking Final state interactions Final state interactions –Complicated even in quasi-elastic case; worse in inelastic

5 July 2002 Kevin McFarland, “  and , oh my” 11 Far detectors at Low E Far detectors at Low E Water-Черенков (not named for a Čzech!!) (Yoshida, Campanelli, Kobayashi, Kajita) Water-Черенков (not named for a Čzech!!) (Yoshida, Campanelli, Kobayashi, Kajita) –Only sees particles over Ч threshold; may miss inelastics –Very good low energy  0 detection A test of  reconstruction! (Casper)   proton   : muon angle p  : muon momentum  quasi-elastic reconstruction (See also Campanelli on improvements)

5 July 2002 Kevin McFarland, “  and , oh my” 12 Far detectors at Low E (cont’d) Sampling Calorimeter at 2 GeV (Para) Sampling Calorimeter at 2 GeV (Para) –Low Z, frequent sampling gives good E resolution –  0 (or other NC)/e - separation can be achieved e-e-   

5 July 2002 Kevin McFarland, “  and , oh my” 13 Far detectors at Low E (cont’d) Liquid Argon on the cheap? (Cline, McDonald) Liquid Argon on the cheap? (Cline, McDonald) –We hold the following truth to be self-evident: that event reconstruction in Liquid Argon is outstanding (happy July 4 th !) –ICARUS T600 analysis underway e-e-   

5 July 2002 Kevin McFarland, “  and , oh my” 14 Beam Flux Monitoring BooNE (Coney) BooNE (Coney) –problem is monitoring e sources ( , K + ) Little  Counters

5 July 2002 Kevin McFarland, “  and , oh my” 15 Beam Flux Monitoring (cont’d) NUMI Gedanken Flux (Szleper) NUMI Gedanken Flux (Szleper) –transform near to far flux, even off-axis A bottle of Sake is at stake… A bottle of Sake is at stake… –Para predicts that applied to K2K, error goes to 1%

5 July 2002 Kevin McFarland, “  and , oh my” 16 Beam Flux Monitoring (cont’d) K2K… champions of low E flux (Kobayashi) K2K… champions of low E flux (Kobayashi) –detailed check with pion monitor system (beautiful talk… but I lost the slides! Sorry!) –allows for energy dependent flux extraction by monitoring secondary beam External data plays External data plays an important role –HARP will help! drift chambers cherenkov TOF wall electron identifier spectrometer magnet TPC/RPC solenoid magnet forward trigger forward RPC muon identifier “characterized” beam

5 July 2002 Kevin McFarland, “  and , oh my” 17 Near Detectors Two types of near detector systems Two types of near detector systems –Mimic far detector as closely as possible study detector response study detector response near/far ratio test near/far ratio test –Build a detector capable of measuring details of neutrino interactions cross-section studies cross-section studies Nuclear effects may eventually require us to merge these functions! Nuclear effects may eventually require us to merge these functions!

5 July 2002 Kevin McFarland, “  and , oh my” 18 Near Detectors (cont’d) NUMI (Morfin) NUMI (Morfin) –Strategy here is to mimic far detector –Also contemplating a cross-section detector for high energy cross-section studies

5 July 2002 Kevin McFarland, “  and , oh my” 19 Near Detectors (cont’d) K2K has a near detector complex! (Kajita) K2K has a near detector complex! (Kajita) –muon range for beam position (high mass) –1kTon H2O-Ч for near/far ratio –Sci-Fi for cross-section studies flux and direction

5 July 2002 Kevin McFarland, “  and , oh my” 20 Near Detectors (cont’d) K2K fine-grained detector upgrade (Kajita) K2K fine-grained detector upgrade (Kajita) –full QE reconstruction to low p p ! Monte Carlo

5 July 2002 Kevin McFarland, “  and , oh my” 21 Near Detectors (cont’d) JHF2K plans inherit from K2K (Kajita) JHF2K plans inherit from K2K (Kajita) –280m (cross-section, position) detector –2km near/far detector ν 15.2 m 8m8m 4m4m

5 July 2002 Kevin McFarland, “  and , oh my” 22 Near Detectors (finally…) NUMI 0.7 o OA may also be able to accommodate a near OA detector NUMI 0.7 o OA may also be able to accommodate a near OA detector –2 GeV cross-sections, NUMI OA flux –EOI to FNAL PAC; could run in 2005

5 July 2002 Kevin McFarland, “  and , oh my” 23 Conclusions At NuFact09, we will… At NuFact09, we will… Low Energy Superbeams likely require: Low Energy Superbeams likely require: –Detailed attention to cross-section, flux –Systems of near detectors, beam monitors Supporting production, cross-section experiments? Supporting production, cross-section experiments? Learn that the uncertainty on  (  12 C->  11 C+n+  0 ) limits our knowledge of  13,  ? Pat ourselves on the back for measuring cross-sections, fluxes and detector response! Find the e component of our anti- neutrino beam was twice as high as we thought… but just wait ‘til NuFact19!