MACRO Atmospheric Neutrinos Barry Barish 5 May 00 1.Neutrino oscillations 2.WIMPs 3.Astrophysical point sources

Neutrino induced upward-travelling muons are identified by the time-of-fligth method   scintillator streamer track   T 2 -T 1 ) * c / l

External -interactions642 used in neutrino flux analysis 213 no cut L ABS > 2 m 55 detector construction Internal -interactions116 used in neutrino flux analysis Different data sets are used in the different searches in order to optimize the ratio SIGNAL / BACKGROUND

Conclusions  MACRO: !through-going muons : angular distribution more regular than in the past, !sterile neutrino disfavored at ~ 2 sigma !low energy events: 90% region of oscillation parameters in favor of oscillation  SuperKamiokande SOUDAN2 MACRO are consistent

WIMPS indirect detection  WIMP capture in gravitational field of the sun or the earth  WIMP-WIMP annihilation  Detect the emitted neutrinos  v<v esc Earth or Sun 

WIMPS indirect detection  high energy upward muons  hadrons  points to sun or earth’s center

Supersymmetric WIMPS Neutralino  The most interesting dark matter candidate is the Neutralino  In MSSM, mass, cross section, etc are determined by three parameters

WIMPS capture and annihilation  Capture !local dark matter density  = 0.3 GeV/cm 3 !dark matter velocities Maxwell distribution !Earth velocity relative to galaxy v = 300 km/sec !Earth model (Anderson)  WIMP Annihilation Cross Sections !Capture rates calculated by Gould !Annihilation process similar to e + e -, except for different branching ratios

WIMPS capture rate in the earth

WIMPS upward muon flux  WIMP annihilation in the earth »mean free path for strong interaction in the center of earth (r ~ 13 g/cm 3 ) is short »length ~ 0.1cm, implies that any particle with  >> sec will interact before it decays and will not make high energy neutrinos

WIMPS angular size of the signal  Sun !source size ~ 0.5 deg !angle between neutrino and muon !angular resolution of detector

WIMPS angular size of the signal  Earth !source size ~ 14 0 (20 GeV/M) 0.5 !angle between neutrino and muon !angular resolution of MACRO

WIMPS Upward muons from Earth  Distribution relative to the zenith  exposure 2620 m 2 yr  517 events

WIMPS upward muon flux limits  Center of Earth (517 events)  Sun (762 events, including semicontained)

WIMPS Upward muons from the Sun  angular separation from sun  exposure 890 m 2 sr  762 events (+semicontained)

 MACRO flux limits from Earth  Varying model parameters (Bottino et al) WIMPS Supersymmetric Models

 MACRO flux limits from Sun  Varying model parameters (Bottino et al) WIMPS Supersymmetric Models

 MACRO flux limits from Earth  Varying model parameters (Bottino et al)  DAMA requires relatively high cross section with earth elements and/or high local density. WIMPS comparison with DAMA

 MACRO has performed searches for astrophysical “point-sources” of neutrinos, including earth and sun.  No signal indicated from either the earth or sun  For the Earth and Sun, flux limits have been interpreted with respect to neutralino dark matter models.  These searches are complementary to both accelerator and direct CDM searches. MACRO WIMP Indirect Searches

 The comparison between MACRO limits and neutralino models suggested by the positive observation from DAMA are of particular interest.  The current MACRO data significantly limit the allowed range of models, particularly at lower M . >Future MACRO data will be able to confront most of the allowed model region. MACRO WIMP Indirect Searches

Neutrino Astronomy  External interactions  No 2 m cut  Detector construction  Internal interactions 1026 upgoing  to search for point sources correlation with GRB }

The angle   evaluated by means of simulation : spectradN /dE ~ E  kinematics of   CC interactions multiple scattering of  through the rock detector angular resolution What cone for point source search ? Atmospheric  background simulation : in declination bands  = 5 0, 100 mixings of local coordinates and times of real events

Cumulative analysis for selected sources 3 0 half-cone 5 0 half-cone half-cone Sources : 40 selected, 7 with TeV  -emission, 220 SN remnants, 129 Egret sources Expected rates in MACRO assuming  ~   : 5x10 -3 ev/yr from Crab Nebula 1x10 -2 ev/yrfrom MKN 421 No excess (Flux limits are ~ 20 times higher than largest expected signal) data expected bck Normalized distributions for 40 sources

Search for clusters of upward-going muons Normalized distributions 3 0 half-cone 5 0 half-cone half-cone data expected bck No statistically significant clusters

MACRO Area for Astronomy Analysis  yield

Flux Limits for Selected Sources Limits at 90 % c.l. (E  > 1 GeV,  = 2.1)

Search for and GRB correlation GRBs and neutrino events vs year GRBs from April 1991 up to May 1999 from BATSE Catalogues (3B and 4B) The transience of GRBs improves the association with observed events using arrival direction and time

“Cumulative” analysis Search cones of 3 0, 5 0, 10 0 have to contain 71%, 85% and 97% of the signal Background estimate : 100 random associations of local angles from upward-going events with times + a shift in the local angles of ± half-cone 3 0 half-cone Normalized distributions of the number of upward-going  ’s and expected background in cones with respect to direction of GRBs No evidence for an excess of events from GRB directions 5 0 half-cone Expected background

Space-Time correlation Search window : 10 0 around GRBs and ± 200 s Background estimate : 40 shifts of time difference (minimum ÷ 4000 s; maximum ÷ s) between upward-going  ’s and GRBs MACRO area for average burst : 130 m 2 Time GRB/upgoing  vs angular separation cos  GRB-UP  0 events observed in 10 0, 0.04 expected Upper limit 7.3 x  cm -2 for average burst GRB-UP  time (s) 10 0

CONCLUSIONS  MACRO data on atmospheric neutrinos favor     oscillation hypothesis  Limits for WIMPs (neutralinos) constrain MSSM models  Upper limits for Dark Matter searches and astronomy : No signal  MACRO is monitoring the “visible” sky using one of the largest sample of high energy neutrinos