Milagro Status Report - October 1998Milagro Status Report - October 1998

October 1998

The Milagro ProjectPhysics GoalsOverall DesignMilagrisimo - Milagrito - MilagroComparison of Milagro to other detectors

MilagritoThe DetectorOperationsResults

Status - Milagro Installation ScheduleBudget History

Physics Goals and Status of Physics Goals and Status of MilagroMilagro

The Milagro CollaborationThe Milagro CollaborationOctober 1998October 1998

M.L.Chen, and J.A. Goodman,* G. Sullivan, D. Evans

University of Maryland At College Park

A. Shoup, and G.B. Yodh,

S. Hugenberger, I. leonor

University of California, Irvine

D.G. Coyne, D.E. Dorfan, L.A. Kelley D.A. Williams S. Westerhoff

W. Benbow, J. McCullough, M. Morales, T. Yang

University of California, Santa Cruz

A.I. Mincer, and P. Nemethy, L. Fleysher, R. Fleysher

New York University

R.W. Ellsworth

George Mason University

D. Berley

National Science Foundation

G. Gisler, T. J. Haines, C.M. Hoffman*, R. Miller,

and C. Sinnis

Los Alamos National Laboratory

B. Shen, A. Smith , O.T. Tumer,

K. Wang, M. Wascko

University of California, Riverside

M. McConnell, J. Ryan, A. Falcone

University of New Hampshire

B. Dingus, J. McEnery, R. Atkins

University of Utah

*Spokesmen Students

NSF EP Supported

Groups

Doe & other

Supported

Groups

High Energy Cosmic Ray DetectorsHigh Energy Cosmic Ray Detectors

10 9 10 11 10 10 10 1013 15 17 19

1 G eV 1 TeV 1 PeV 1 EeV

The Cosmic Ray Spectrum

Satellites

Fly’s Eye / HiRes

Air Cherenkov

Milagro

EAS Arrays

Solar Arrays

Akeno /Auger

A Water Cherenkov DetectorSensitive over 100% of the areaSensitive to Photons and Electrons

A Low Threshold - Open Aperture DetectorThreshold < 300 GeV

Significant Area at 100 GeVLarge Duty CycleAcceptance ~ 1srAngular Resolution < 0.50 (better for large

showers)

MilagroMilagro

MilagroMilagro

Built in an Existing 60x80x8m Pond450 Top layer 8” PMT’s on 3m grid273 Hadron/ layer PMT’s (facing up)

High Altitude Location - 8650’ Existing Lab Tech Area Support Facilities at the Site

Air Shower Layer

Hadron/Muon layer

2m

8" PMTs

Light-tight Cover

Physics with MilagroPhysics with Milagro

First All Sky Survey of the Northern Sky Search for DC SignalsLook for New SourcesSearch for Bursts on Many Time Scales

Study the Signal from the CrabMilagro will observe the Crab with >5in a few

months (using the Whipple Flux)Milagro will study the spectrum & flux

Absolute flux normalization from ACT’s is important and needs to be confirmed

Data on the high energies is needed for acceleration models

Search for Gamma Ray BurstsEGRET has seen burst events up to ~20 GeV with

Aeff of ~400 cm2

Milagro at 100 GeV will have Aeff20 m2 (more than ~500 x EGRET)

Milagro’s acceptance grows like E2 up to 1 TeVMilagro operates continuously with a wide aperture -

It will be the best high energy GRB detector!Measuring a cutoff above a TeV would constrain

GRB models and distance to the source

The CrabThe Crab

Energy (TeV)

Inte

gral

Flu

x (c

m-2 s

-1)

Whipple (a)Themistocle (b)ASGAT (c)HEGRA Cherenkov (d)Cangaroo (e)

MilagroSensitivity

Detections

Upper LimitsBaksanCASA-MIACYGNUSEAS-TOPHEGRA Scint.TibetUtah Cherenkov

FGHIJKLK

G

FL

I

I

I

J

H

Physics with MilagroPhysics with Milagro

Study AGN’sMRK 501 has be seen by MilagritoEGRET has seen >30 AGN’s Milagro will search for variability in AGN’s at TeV

energies Sources have shown increases x ~100 All northern sources can be viewed every day

with Milagro Correlation with Radio Observations

HEGRA has events at >20 TeV from Mrk501The nature of the spectrum above a few TeV is

important in determining where / if absorption is occurring

Primordial Black HolesPBH’s will radiate energetic particles at the end of

their lifetime The spectrum of particles radiated will be depend

on physics model - SUSY etc.Milagro will be sensitive to the last few minutes of a

PBH explosionCygnus set limits on PBH that were 100x better than

any otherMilagro should do about 2-3 orders of magnitude

better

Primordial Black HolesPrimordial Black Holes

PBH’s will radiate particles at the end of their life

The radiation will depend on the number of degrees of freedom

Milagro will be sensitive to particles produced in the last ~1000 seconds

Seconds Until End

Num

ber

of D

etec

ted

Eve

nts

Time

Background

SUSY

Physics with MilagroPhysics with Milagro

Solar PhysicsMilagro will detect the shadow of the sun in a

few daysThe position and disappearance of the

shadow are a measure of the solar Bperp

Currently measurements are poorGeV Solar flares give muons in the bottom

layer 2500 m2 will allow us to measure solar

flare structure on a 1 sec time scale vs 10’s of minutes

Milagrito already has a probable detection of a CME event

Proposal to ATM from UNH (muon direction) Antimatter Search

There will be a second displaced shadow if there is a significant amount of antimatter

Composition StudiesWide Area Cherenkov Telescope Proposal

MilagrisimoMilagrisimo

Milagrisimo was the first stage of Milagro30 PMTs were operated in the Milagro

Pond in winter of 1995-1996Single layer on the bottom of the Pond~1.5m of water above tubesDesign studies and analysis presented in

at Durban ICRC

MilagritoMilagrito

Milagrito was the second stage of the Milagro detector

It was a large area water detector Area ~ 2/3 Milagro No Muon Layer

Milagrito data was used for: design studies and development

And it will be used for physics & theses Physics (MRK 501, GRB’s etc) Student Theses

M ilagrito Milagrito operated at >250Hz from

February 1997 to April 1998 (>85% livetime) More than 9 billion events - 9 Terabytes

MilagritoMilagrito

Milagrito Trigger Rate

10

100

1000

10000

0 50 100 150 200PMTs in Coincidence

Tri

gg

er R

ate

(Hz)

MilagritoMilagrito

One Month Coverage

Milagrito ResultsMilagrito Results

Moon Shadow

Offset is approximately what is expected at our energies.

Antimatter shadow location

Milagrito ResultsMilagrito Results

Mrk501

Nov. 6 1997 Coronal Mass EjectionNov. 6 1997 Coronal Mass Ejection

Milagro SiteMilagro Site

HDR SiteMilagro Site

Ops Building

Million Gallon Pond

Milagro SiteMilagro Site

Counting House

Pond Utility Building (PUB)

Office Trailer

Testing Trailer

Milagro ConstructionMilagro Construction

Cover Inflated with new webbing

Lightning protection system

Late LightLate Light

BafflesBaffles

Milagro ConstructionMilagro Construction

4 Muon Boxes deployed to provide redundant ID

Milagro ConstructionMilagro Construction

MilagroMilagro

Milagro will have a trigger rate of ~2 kHzData will be processed in real timeWill perform online search for burstsTime and pulse height on each channel

The muons will provide substantial background reduction for showers above a few TeV

<Nmu>detected = 1 at 1 TeVAt high energies Milagro will have low

background Muon/Hadron layer may provide other

methods of background rejectionA real gamma signal can be studied from

sources like the Crab to develop better rejection algorithms

Water tanks are needed to surround the pond to get core position

Core position is needed for angular resolution and energy determination

MilagroMilagro

MilagroMilagro

MilagroMilagro

Event ReconstructionEvent Reconstruction

Milagrito Milagrito

Why We Need OutriggersWhy We Need Outriggers

What are outriggers?An array of water tanks outside the pondWe have built & operated a prototypeOutriggers were part of the original

Milagro proposal Outriggers are essential for locating core

positionNeed counters outside the pond to tell if

cores are inside or outside Energy Determination needs core position

Need core to determine shower size and lateral distribution - This is vital for AGNs and GRBs

Angular ResolutionCurvature correction needs core position

Proton/Gamma DiscriminationProton showers trigger further from the

pondGammas trigger more often on the pond

Major Responsibilities on MilagroMajor Responsibilities on Milagro

Milagro is a strong collaboration of University Groups and Los Alamos

A project supported by both NSF & DoEAll groups share responsibility for operating the

detector Irvine

PMTs - testing, encapsulation… Los Alamos

OperationsSite

Santa CruzElectronicsCover Inflation systemLightning Protection

MarylandDAQ

New HampshireSolar Outriggers

NYUPMT structure and deployment

Utah WACT

1994 Funding begins toward a $2.6M Project (80%NSF 20%DoE) 1995 Site Preparation - New liner & cover - PUB - Counting House

- PMT structure installed 1995 -1996 Milagrisimo run - 38 tubes on pond bottom 1996-1997 Milagrito installed - Data taking begins Feb 1997 1997 Lightning protection system 1998 Milagro tubes installed, modifications to electronics, cover,

water system completed (based on Milagrito experience) Winter 1998-1999 Running to begin

$0

$500

$1,000

$1,500

$2,000

$2,500

1994 1995 1996 1997 1998 1999

FY

Tota

l Fu

nd

s in

Th

ou

san

ds

NSF

DoE

Site

Work Milagrisimo Milagrito Milagro

Timeline & Funding ProfileTimeline & Funding Profile

SummarySummary

Milagro is an important new detector that will produce significant new physics results

GRB, AGNs, Solar Physics, PBH, Antimatter, Composition

Milagro has a strong collaborationNSF Groups, DoE Groups & Los Alamos

Milagro has been built in stagesWe have learned how to build and operate

the detector through prototypes The project has been on time and on budget

We built it for the cost proposed in 1991We built as fast as the cash flow allowedWe have met all the technical challenges

Outriggers are essential to finish to MilagroCore position is central to Milagro’s goalsProposal this winter for outriggers

Solar Physics is an added bonusSolar Proposal to ATM

Primordial Black HolesPrimordial Black Holes

Why might they exist?Density Fluctuations in the early universe-

Some regions of space could become overdense and collapse

What did COBE tell us?COBE studied density fluctuations on a huge

scale (1055gm) and found

Other evidenceStandard inflation says is scale invariant If Standard inflation and COBE are correct -

There should be virtually no PBH’sDiffuse 100 MeV ’s set a limit on the number

of PBH’s PBH<10-8 If PBH’s do exist - We might see them when they

evaporate T ~ 1/MThey would radiate all species of particles at

the end of their lifetime Initial mass of ~1015 gm would be going off

now We should look at a scale 40 orders below

COBE