Presented for

Arnulfo Zepeda On behalf of the Mexican Collaboration

Sep. 2000

PHYSICS AND ASTROPHYSICS OF ULTRA HIGH ENERGY COSMIC

RAYS

BUAP CINVESTAV UMSNH UNAM

Material selected and prepared for Rebeca López

GOAL

• To develop physics and astrophysics of ultra high energy cosmic rays through the participation of Mexican scientists in the construction of the Pierre Auger Observatory.

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CONTENTS

• Antecedents on cosmic rays.

• The Pierre Auger Observatory.

• The Mexican Participation (this proposal).

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ANTECEDENTS Some major discoveries made with cosmic

rays

• The positron (the first antimatter sample), 1933.

• Extended air showers, 1938.

• The muon (first relative of the electron), 1943.

• The pion (the carrier of nuclear interactions, postulated by Yukawa), 1947.

• Particles with strangeness, 1947.

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Technics for detection of cosmic rays

COSMIC RAY FLUX

• Cosmic rays are produced in explosive astrophysical events.

• The low and medium energy spectrum is reasonable weel understood.

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The complete diffuse background radiation over the

spectral region 10-9-1020 eV.

ULTRA HIGH ENERGY COSMIC RAYS

• Cosmic rays may be produced with ultra high energy in exotic sources.

• They may be further accelerated in strong magnetic fields and plasma shock waves.

• Then they travel in the interstellar medium, which is never empty.

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Possible sources of high energy

cosmic rays

Possible sources of high energy

cosmic rays

XZ Tauri

HH 30

ULTRA HIGH ENERGY COSMIC RAYS

• The interstellar medium is filled with low density radiation, the cosmic microwave background radiation, which originated during the early live of the Universe, at the time of the formation of atoms, at about 400,000 years after its birth.

• Cosmic rays interact with the CMBR and if their energy is high enough, then their energy materializes into matter, pions are produced with high probability. Thus high energy cosmic rays loose soon their energy.

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N u c l e i + ( M B R )

N 1 + N 2 + p ’ s + n ’ s + ’ s

l t l o s s e s a b o u t 2 n u c l e o n s p e r M p c

F o r E 1 0 E e V o n l y p r o t o n s s h o u l d b ec o n s i d e r e d

P r o t o n s

I f E 0 . 5 E e Vp + p + e + e -

I f E 5 0 E e V = 0 . 5 x 1 0 2 0 e V p +

pn

G Z K c u t o f f

G r e i s e n – Z a t s e p i n - K u z ’ m i n ( 1 9 6 6 )H i l l + S c h r a m m ( 1 9 8 5 )L u i s A n c h o r d o q u i + D o v a + E p e l e + S w a i n ( 1 9 9 7 )

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _n ’ s , + ’ s ’ s ° 2 + e + e -

E 1 0 1 4 e V

PROCESSES ON THE CMBR

THE GZK CUTOFF

• There is a limit, at around 5 X 1019 eV to the energy with which cosmic rays may arrive to the Earth from far away (50 Megaparsecs)

This is the GZK cutoff.

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AGASA Energy Spectrum

Implications of events beyond the GZK cutoff

• Suggest the existence of exotic sources?

- Quasi-stable massive particles.

- Supersymmetric matter.

- Topological defects.

• Violation of Lorentz invariance?

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EXPOSURES OF UHECR DETECTORS

. Km2 sr year

1020 N(1020) Expected

Volcano Ranch -60 1 0.34(1962)

Haverah Park 270 4 1.6(1987)

Fly’s Eye 167 0 1.0(stereo)

Fly’s Eye (mono) -600 1 2.4(1993)-------------------------------------------------------------------------------------

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EXPOSURES OF UHECR DETECTORS

.Km2 sr year

1020 N(1020) Expected

AGASA 1223 7 7.0(1999)

Yakutsk 933 4 5.4(1999 – reanalysis)

HiRes 1090 7 6.3(1999)

Pierre Auger 14000 60

24 events 1020 eV

Rate = 0.6 km-2 sr -1 century -1 R. LópezR. López

PIERRE AUGEROBSERVATORY

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The shower

MAIN OBJECTIVE OF THE PIERRE AUGER

OBSERVATORY

• To understand the origin and nature of the ultra high energy cosmic rays, one of the major mysteries of modern physics.

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GOALS OF THE PIERRE AUGER OBSERVATORY

• Detect a good number of ultra high energy events.

• Measure with precision the energy of the primary cosmic particle.

• Determine the incoming direction.

• Identify the nature, type of particle.

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Consequences of the Pierre Auger

Observatory data

• In astrophysics.

• In the theory of elementary particles.

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Hybrid Detector

How water Cherenkov detectors work

SCHEME OF THE FLUORESCENCE

DETECTOR

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SIMULATION

• The computer simulation of

- The shower

- The detectors

- The electronics

• Shows that the designed observatory will fulfill its objectives.

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#S

#S

Sites of the Pierre Auger Observatory

Auger Observatory Exposure

Sky as seen by observatories, 60° max shower zenith angle.

North --> red, South --> green.

Pampa Amarilla Site

• On March 17th 1999 work at the site in Mendoza began. Construction will continue till 2003 although observations will begin by 2001

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The first water Cherenkov detector in Malargue

Plan of a Fluorescence

Detector Building.

Los Leones

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Construction of the Central Station

Building.

International Collaboration Metting

Cost and contributions

• The total cost of both observatories is 100 million dollars.

Approved:

Argentina

CNEA 10,000

Mendoza 5,000

Brazil 2,000

France 2,300

Germany 5,500

Mexico 300

Slovenia 500

UK 1,000

US 9,000

35,600

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Cost and contributions

• Pending approval:Australia 600

Bolivia 30

China 1,000

Greece 200

Italy 3,200

Mexico 2,650

Poland 50

------

7,730

TOTAL 43.300

The rest of the countries in the collaboration are about to submit their applications.

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Schedule

• Construction of Southern Observatory

Start: March 1999

End: end of 2003

First face: Engineering Array:

40 WCDs and 2 FDs

Communication network

Data collection system

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Schedule

End construction:

end of 2001

Start taking data:

January 2002

Construction of Northern Observatory

Start: 2003

End: 2005

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Finance Board

• Agreement for the Organization, Management and Funding of the Pierre Auger Observatory

• Among Science Founding Agencies of Countries in the Pierre Auger Collaboration

• Signed at Mendoza, Argentina, March 16, 1999.

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THE MEXICAN GROUP

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Participants

Institution Researcher Technicians Students

BUAP 10 1 17

Cinvestav 6 1 4

UMSNH 3 2

UNAM 4 2

23 4 23

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Specific goals

of the Mexican grup

• Tecnological Development.

• Research activities.

• Involve the national industry.

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Fuorescence Detector

• Design of optical system (special recognition by the project management).

• Electronics.

• Development of a tester for mirror quality.

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Surface Detector

• Water Purity.

• Reflective properties.

• Methods of calibration and monitoring.

• Requirements for local trigger.

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Surface Detector

• Design and construction of the container and of the liner: local

• development and international coordination (by the task leader).

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Surface Detector

• Design and development of the central triggering system and of the data acquisition system.

• Installation of first tanks.

• Installation and operation of the array of surface detectors.

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Rotoplas

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Computer simulation

- Atmospheric shower.

- Response of the detectors.

- Reconstruction of data.

- Test of high energy hadronic interaction models.

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Students who have finished their thesis

Degree Institution

631

BachelorMasterPh. D.

BUAP

1 Ph. D. CINVESTAV

2 Bachelor UMSNH

13

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Students working on their thesis

Degree Institution

451

BachelorMasterPh. D.

BUAP

5 Ph. D. CINVESTAV

11

BachelorPh. D. UMSNH

17

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Students to graduate between 2001 and 2004

YEAR BACHELOR MASTER Ph. D.

2000 3 2 2

2001 4 2 3

2002 4 3 1

2003 4 3 3

2004 4 3 3

19 13 12

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BUDGET FOR THE MEXICAN PROGRAM

in thousands of US dollars.

• R and D (travel, computers, prototype components)

1996 .... 35

1999 .... 60

2000 .... 42 (Cinvestav)

2000 ....130 (BUAP)

2001-4...328 THIS PROPOSAL

• Observatory components

2000 .... 300 (BUAP)

2001-4..2650 THIS PROPOSAL

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