Bari, Bologna, Boston, Caltech, Drexel, Indiana, Frascati, Gran Sasso, L’Aquila, Lecce, Michigan, Napoli, Pisa, Roma I, Texas, Torino with mmary is of High and Low energy neutrino events e vs Tau neutrino oscillations (matter eff A. Surdo INFN - Lecce
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Bari, Bologna, Boston, Caltech, Drexel, Indiana, Frascati, Gran Sasso,
Surdo INFN - Lecce. Oscillations in Atmospheric Neutrinos. with. Bari, Bologna, Boston, Caltech, Drexel, Indiana, Frascati, Gran Sasso, L’Aquila, Lecce, Michigan, Napoli, Pisa, Roma I, Texas, Torino. Summary Analysis of High and Low energy neutrino events - PowerPoint PPT Presentation
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Bari, Bologna, Boston, Caltech, Drexel, Indiana, Frascati, Gran Sasso,L’Aquila, Lecce, Michigan, Napoli, Pisa, Roma I, Texas, Torino
with
Summary• Analysis of High and Low energy neutrino events• Sterile vs Tau neutrino oscillations (matter effects)
A. Surdo INFN - Lecce
MACRO @ Gran Sasso
• GUT Monopole and rare particle search• Cosmic ray physics• Neutrino bursts from stellar collapses• Study of atmospheric neutrinos• Neutrino astronomy• Indirect search for WIMPs
Data taking: Mar 1989 – Dec 2000(complete detector since Apr ’94)
Main features of Macro as detector
• Large acceptance (~10000 m2sr for an isotropic flux)
• Low downgoing rate (~10-6 of the surface rate )
• ~600 tons of liquid scintillator to measure T.O.F. (time resolution ~500psec)
• ~20000 m2 of streamer tubes (3cm cells) for tracking (angular resolution < 1° )
More details in Nucl. Inst. and Meth. A324 (1993) 337.
Up stop
In down
In up
Up through
Neutrino event topologies in MACRO
• Detector mass ~ 5.3 kton
(1) Up throughgoing (ToF)(2) Internal Upgoing (ToF)(3) Internal Downgoing (no ToF)(4) UpGoing Stopping (no ToF)
Absorber
Streamer
Scintillator
(1) (2)(3)
(4)
Energy spectra of events
detected in MACRO
• Emedian ~ 50 GeV for Throughgoing muons;
• Emedian ~ 4.5 GeV for Internal Upgoing (IU) ;
• Emedian ~ 3.5 GeV for Internal Downgoing (ID)
and for UpGoing Stopping (UGS) ;
Low energy events (IU, ID+UGS) allow to investigate the oscillation parameter space independently from throughgoing muons
1
T1 T2 T3 T4 c2L
+1
-1 T1
T3 T4
T2
L>2.5mStreamer tube track
Upward Throughgoing muons
Analysis and Data Set
* evaluation:
1) agreement between streamer track and scintillator counter hits (position from times at the ends)
2) -1.25 < 1/ < -0.75
3) 2m (~200 g/cm2) of absorber crossed to reduce at 1% level the bck due to ’s produced by muons (Astrop. Phys. 9 (1998) 105)
• Automated data selection procedure (no visual scan)
• 863 induced upward through-going muons during:
* Background rejection cuts:
Event selection based on time-of-flight method
Mar 89-Nov 91 (1.4y) Dec 92-Jun 93 (0.4y) Apr 94-Dec 2000 (5.5y)
(a) No T.o.F. measurement(b) topological constraints on track (bottom SC layer + track inside fiducial volume)(c) visual scan procedure for final selection(d) >100 g cm-2 of material crossed in the detector
UGS ID
IU events
From MC simulation:
• E ~ 5 GeV• ~ 87% due to -CC interactions
DATA: 5.5 live-y
DATA - Bck(1/) = 154 events
• From Apr. 1994 up to Dec. 2000• 1/ distribution after all analysis cuts: