MACRO Atmospheric Neutrinos 1 Neutrino oscillations 2 WIMPs

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

m Neutrino induced upward-travelling muons are identified by the time-of-fligth method n scintillator streamer track scintillator T 2 -T 1) * c / l

External -interactions 642 used in neutrino flux analysis 213 no cut LABS > 2 m 55 detector construction Internal -interactions 116 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 § Super. Kamiokande SOUDAN 2 MACRO are consistent

WIMPS indirect detection § WIMP capture in gravitational field of the sun or the earth § WIMP-WIMP annihilation § Detect the emitted neutrinos c v<vesc Earth or Sun c

WIMPS indirect detection § high energy upward muons hadrons nm 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 r = 0. 3 Ge. V/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. 1 cm, implies that any particle with >> 10 -11 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 ~ 140 (20 Ge. V/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)

WIMPS Supersymmetric Models § 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 comparison with DAMA § 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.

MACRO WIMP Indirect Searches § 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 Mc. >Future MACRO data will be able to confront most of the allowed model region.

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

What cone for point source search ? The angle Qm-n evaluated by means of simulation : • n spectra d. N /d. E ~ E-g • kinematics of nm CC interactions • multiple scattering of m through the rock • detector angular resolution Atmospheric background simulation : in declination bands Dd = 50, 100 mixings of local coordinates and times of real events

Cumulative analysis for selected sources Sources : 40 selected, 7 with Te. V g-emission, 220 SN remnants, 129 Egret sources Expected rates in MACRO assuming F ~ Fg : 5 x 10 -3 ev/yr from Crab Nebula 1 x 10 -2 ev/yr from MKN 421 Normalized distributions for 40 sources 1. 50 half-cone data expected bck 30 half-cone 50 half-cone No excess (Flux limits are ~ 20 times higher than largest expected signal)

Search for clusters of upward-going muons Normalized distributions 1. 50 half-cone data expected bck 30 half-cone 50 half-cone No statistically significant clusters

MACRO Area for Astronomy Analysis yield

Flux Limits for Selected Sources Limits at 90 % c. l. (Em > 1 Ge. V, g = 2. 1)

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

“Cumulative” analysis Search cones of 30, 50, 100 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 ± 100 Normalized distributions of the number of upward-going ’s and expected background in cones with respect to direction of GRBs Expected background 30 half-cone 50 half-cone 100 half-cone No evidence for an excess of events from GRB directions

Space-Time correlation Search window : 100 around GRBs and ± 200 s Background estimate : 40 shifts of time difference (minimum -4000 ÷ 4000 s; maximum -80000 ÷ 80000 s) between upward-going m’s and GRBs MACRO area for average burst : 130 m 2 GRB-UPm time (s) Time GRB/upgoing vs angular separation 100 cos Dq. GRB-UPm 0 events observed in 100, 0. 04 expected Upper limit 7. 3 x 10 -10 cm-2 for average burst

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