the nalta project – a north american network of sparse very large area air shower arrays a...

THE NALTA PROJECT – A NORTH AMERICAN

NETWORK OF SPARSE VERY LARGE AREA AIR SHOWER

ARRAYS

A research project that involves

students (high-school, undergraduate + graduate), teachers and Universities in

North America

James Pinfold University of Alberta

James Pinfold Prague June 2004

• The cosmic ray energy spectrum• The GZK limit and Ultra High Energy Cosmic Rays• Detecting cosmic rays – Extended air showers (EAS)• Cosmic ray experiments around the world – a brief

look• Tantalizing hints of a non-random component of high

energy cosmic rays• Sparse very large area EAS array network • Sparse very large area “educational” arrays• NALTA• The ALTA network , an example• The proposed EEE array in Italy• Closing remarks


A list of Fundamental A list of Fundamental QuestionsQuestions

• How is the HECR spectrum made up?– What is the dominant source for CR below the

knee?– What is the origin of the “knee” of the CR

spectrum?– What is the origin of particles above the knee?– At what energy are the fluxes of galactic &

extra-galactic cosmic rays are equal?– What are the sources of extra galactic rays?– What is happening at the GZK cut-off around

the “ankle”?

• What is the nature of the exotic (centauro, etc.) events observed largely at high altitudes?

• Is there any evidence of non-random component of cosmic rays (large area coincidences, bursts, sources, etc)


The Energy RangeThe Energy Range

• High energy cosmic rays consist of protons, nuclei, gammas,…

• Measured flux extends to s1/2 ~ 400 TeV

• Highest energy particles are extremely rare

• Supernova shock fronts can accelerate particles upto 1015 eV

• Above ~1015 eV, presumably acceleration is in AGNs (?)

• How do UHECR protons evade the GZK cut-off at ~7 x 1019 eV (if source is >100Mps away)?

GZKCut-off

“Knee”

“Ankle”

1/m2/s

1/km2/year

1/m2/year


Mysteries of the SpectrumMysteries of the Spectrum• Protons are trapped in our Galaxy (G B-fields) up to ~1017 - 1018eV• Protons can travel straight above ~1020eV• Supernova shockwave acceleration up to ~1015 eV• Above the knee the acceleration mechanism is essentially

unknown: AGNs, massive black holes systems, gamma ray bursts ?

1018 eV

1020 eV

GZKland


Acceleration of CRs above the Acceleration of CRs above the KneeKnee

• Up to the knee Fermi acceleration (FA) in supernova shock fronts can “explain” the spectrum: Emax ~RSNR x Z x B x sh

• This can be used to constrain the size and magnetic field requirement if acceleration mechanism is 1st order FA.

• Only AGNs and GRBs have sufficient “R x B” to be candidate acceleration sites

• However, we have a lack of candidate sites for energies above 1020 eV.

The HILLAS Plot


The Mysteries of an Opaque The Mysteries of an Opaque UniverseUniverse

• The universe is opaque to UHECR • In the case of the GZK cut-off a 5x1019 eV proton has a mfp

of 50 mpc due to interaction with photons in the the CMB.• But no nearby sources have been identified, • How are the protons with energy > EGZK

getting to us? There are two scenarios: • BOTTOM UP: acceleration in AGNs, gamma rays bursters,

etc. then production of a neutral (, so,..?). • BOTTOM UP with GZK cut-off relaxed by violation of Lorentz

Invariance, etc.• Or TOP DOWN: topological defects (cosmic strings,

monopoles, etc.) or massive relics, etc.

10,000Mpc

Size of observable universe

Region restrictedby GZK cut-off ~100 Mpc


Life Life AboveAbove the GZK the GZK Cut-offCut-off??

?

GZK HiRes vs. AGASA

UHECRs as of 2001

200 billionparticles

Fly’s Eye Big event 3 x 1020eV (50J!)

(410)x1019eV> 1020 eV

Many events observedAbove the GZK cut-off

AGASA (EAS ground Array) seems to violateThe GZK cut-off

HI-RES (atmospheric. fluorescence ) seems to obey GZK theory

However both expts see events with E > 1020eV

Some debate as to possible sources…

Some 6 doublets and 1 triplet of events have been seen within 2o cones

HI-Res. + AGASA


Extended Air ShowersExtended Air Showers

There are many ways of detecting cosmic rays

EAS properties can be used to estimate the mass & energy of the incident particle using MC

1016eV

15 km

100m

Ne & N correlation

Particle densityat ground level

Particles/m2


EAS -- the Atmosphere as a EAS -- the Atmosphere as a CalorimeterCalorimeter

• Fluorescence Detectors– Atmosphere is sensing calorimeter– Measure the longitudinal distribution

• Ground Arrays– Technique developed in

the 50’s– Measure the lateral distribution at

ground

Transverse profile Longitudinal profile

Auger - measuring transverse &Longtudinal shower profiles James Pinfold Prague June 2004

Measuring EASsMeasuring EASs

• EAS measurement is an indirect method to determine:– mass A of primary CR;– energy E of primary

CR.• These quantities are

inferred from:


Cosmic Rays Experiments Cosmic Rays Experiments WorldwideWorldwide

100 detectorsurface array

Artists impression

Atmospheric flour.2 site 14 km apart

1600 water det.4 atm. fluor.

det.

Expts in space

Cerenekov telecopes

EUSO or OWL

Ice cerenkov


Sensitivity of Future DetectorsSensitivity of Future Detectors


Tantalizing Hints of Non-random Tantalizing Hints of Non-random Cosmic Ray PhenomenaCosmic Ray Phenomena

• The Japanese LAAS array(2000), 8 stations sep. by ~50 km. – Anisotropy of successive air showers – within a t of 20 minutes, a

concentration of directions in the galactic plane is evident – the chance probability is 0.077.

• The Swiss array (1988-89) – 4 detectors enclosing 5K km2.– An excess of events in which each detector was hit within 0.62 ms

was observed with a significance of 4.8 (prob 10-4).

• The Irish (U.C. Dublin/Cork) Array (~1975) – 2 stations each with 4 scintillators, separated by 250 km. – Fegan et al reported an unusual “simultaneous” increase in the

cosmic-ray shower rate at the two recording stations, the event lasted 20s – statistical probability 3 x 10-5.

• The Manitoba Air Shower Array (1980) – consists of three 1m2 plastic scintillators enclosing an area ~60 m2.– A burst of 32 EASs was observed within a 5-min period. This

observation was the only one of its kind in an 18 month period in which 150K of such showers were recorded. Stat. prob. ~ 10-35 !!


Sparse Very Large EAS Array Sparse Very Large EAS Array NetworksNetworks

• Experimental purpose of such array networks is to look for a possible no-random component in cosmic rays:– Look for coincident events

in small windows around arrival time and direction at separated sites (X from 1~500 kms) using GPS timing

• One can detect and point very high energy, multiple primary, phenomena this way

• When detectors are close enough (not more than a few kms) one can count and point UHECR

t


Experimental ConceptExperimental Concept• Small air showers arrays operated

independently at each site: Typically a few to several small detectors at each site separated by ~10m.

• Local pointing with accuracies as good as ±2o

• GPS now provides the common clock with accuracies ~20 50 ns over areas as large as North America.

• Local coincidence data readout to a central site where an “offline” trigger involving direction, time and pulse height can be applied.

• Standard data format and accessibility via the internet James Pinfold Prague June 2004

The Mystery of Very Large Area The Mystery of Very Large Area Cosmic Ray PhenomenaCosmic Ray Phenomena

• Correlated phenomena, Possibilities:– Photo-disintegration of UHE

nuclei in the photosphere of the Sun

– VHE Gamma Rays from GRBs– Relativistic dust grains– Neutrino bursts– Primordial black holes– Cosmic strings– Ultra high energy (UHE)

“horizontal” air showers (giving a coincidence between separated detectors & thus “faking” a correlated event)


The LAAS ArrayThe LAAS Array

Typically very small airshowers arrays (10x10 m2)with about 8 detectors (0.25 m2) at each site.

Typically very small airshowers arrays (10x10 m2)with about 8 detectors (0.25 m2) at each site.

Okiyama University

(First results 1999)


Sparse Very Large Area Networks Sparse Very Large Area Networks of “Educational” EAS Arrays.of “Educational” EAS Arrays.

• Physics aims of these experiments are those of sparse very large area air shower arrays.

• In this case the detectors are housed in high-schools and colleges and involve high-schools students and teachers

• These arrays thus have BOTH an educational component as well as a research component

• The ALTA project in Alberta was the first in North America (& the world?) to actively pursue an array that would satisfy equally these two aims.

• The ALTA experience has been taken up across North America and in Europe.

• ALTA now leads (along with CROP) a consortium of similar projects called NALTA (North American ALTA)


North American Large Area North American Large Area Time Coincidence Arrays Time Coincidence Arrays

(NALTA)(NALTA)• ALTA – U. of Alberta, Athabasca U, (Northeastern

U, Boston)• BC-ALTA – U. of BC• CANLACT – U of Alberta, U. of Athabasca, UBC,

Carleton U., U of Manitoba, U of Regina, U of Victoria

• CosRayHC – U. of Pittsburgh, Southern U. of Illinois at Edwardsville, Jackson State U., Florida State U.

• CROP – U. of Nebraska• CHICOS – Caltech, California State U at

Northridge, U. of California at Irvine• SALTA – SNOWMASS-2001, Colorado• SCROD – Northeastern University• TECOSE – University of Texas• WALTA – University of Washington• MEXICO – Groups around Mexico city

~100 detector systemsAcross North America


•~20 Schools Involved•13 detectors systems deployed in Alberta•2 more being equipped•2 more for next spring•~ 20 detector systems in place by the end of 2004 •All timed together using the GPS system

ALTA The 1ALTA The 1stst Example of a Example of a

Sparse Large Area Sparse Large Area “Educational” Array“Educational” Array

NetworkNetwork


0.5 m2

Scint.

The ALTA Detector Systems GPS

The electronics readout


The System CostThe System Cost• Detector cost 1,900 EUR• Readout electronics &

calibration system 5400 EUR• HV power supplies 600 EUR• Temp. mon. & control 380 EUR• GPS Satellite receiver 630 EUR• DAQ Computer 950 EUR• Sundries 250 EUR

• TOTAL ~ 10,000 EUR

3 x

1 x

GPS Receiver & electronics

1 x

Readout ElectronicsData acquistioncomputer

1 x

Properties of the DetectorProperties of the Detector

• LOCAL COINCIDENCE obtained using local system and hardwired electronics. Allows pointing of shower direction to 2->3 degrees.

• GPS TIME STAMP is obtained when a local coincidence occurs. Timing is good to ~15 ns over Alberta (NIM paper on this has been accepted).

• MIP SENSITIVITY. Each detector should respond to a single MIP.

• ENERGY THRESHOLD for the local detector with a 10m triangle is 1014 eV (from Corsika)

• OFFLINE “TRIGGER” timed stamped local coincidences, or events, are stored centrally for various offline studies. 10m

Average sizeOf a 1014 ev shower


First Data is Being AnalyzedFirst Data is Being Analyzed

• No physics results are ready as yet

• However, we do have a nice result relating to the correlation between trigger rate and atmospheric pressure

• It provides a nice way to check that detectors are working over a large area

Atmospheric pressure

Local coincidence rate

(


TECOSECHICOS

WALTA

BC-ALTA ALTA

CROP

SALTA

SCROD

CosRayHS CosRayHS

CosRayHS

CANALTA

CANALTA

CosRayHS

CANALTACANALTA

Mexico City, etc.)

North American Large Area Time North American Large Area Time Coincidence Arrays (Coincidence Arrays (NALTANALTA))

Detectors in place

In planning

In preparation

CANALTA


An Example of a Proposed Array in An Example of a Proposed Array in Italy – EEE (Extreme Energy Event Italy – EEE (Extreme Energy Event

network))network))• Possibility of 4 sites in

Italy.• Project run under the

auspices of the Enrico Fermi Institute in Rome

• Contact people: Prof. A Zichichi & Dr Rinaldo Baldini.

• As part of this project Prof Zichichi has proposed a search for cosmic ray coincidences with ultra long baselines (between ALTA & EEE) James Pinfold Prague June 2004

Let’s Network the Cosmic Rays Let’s Network the Cosmic Rays Experiments WorldwideExperiments Worldwide

“ALTA” typeprojects in;1) Czeck Republic (planning)2) Germany,3) Italy (planning)4) Denmark

NALTAALTA

Internet based “ALTA” arrays in schools could be networkedwith the World’s largest Cosmic Ray detector system

CANALTA


We Could Include Gravitational Wave We Could Include Gravitational Wave Detectors in the World Wide NetworkDetectors in the World Wide Network


ALTA “Hand on” Workshop Nov. ALTA “Hand on” Workshop Nov. 20012001• Workshop held as introduction to the physics as well as hands

on training with detectors.

The crowded workshoparea

At the U of Alberta

Alberta high-school


The CROP Project (U. of Nebraska)The CROP Project (U. of Nebraska)

• Major funding received from NSF ($1.34M over 5 years)

• 11 high-schools involved in project so far (more to follow)

• Basic detector setup has four plastic scintillators with separation ~10m.

• Enough PMTs scintillators, HV retrieved from Dugway to supply 300 schools. CROP Workshop Participants

July 2000James Pinfold Prague June 2004

The CROP Project July WorkshopThe CROP Project July Workshop

The Zoo School (Lincoln) team wrapping a CASA scintillator 25 July 2000


The CHICOS Project (U. of The CHICOS Project (U. of California)California)

• Proposing to involve 14 high-schools in the array in the Los Angeles “area”

• Plan is to field detectors in schools in the San Gabriel valley in 2001

• Prototype detectors stations are working (refurbished CYGNUS detectors)

• 200 detectors and PMTS in hand from LANL.


Summary & ConclusionsSummary & Conclusions• Around 15 universities & ~80 high-schools involved so far• 42 detector systems have been deployed (ALTA has 9, CHICOS

18, CROP 11, WALTA 4) -- we expect to deploy ~100 in a few years.

• NALTA like efforts are now international with projects in: Canada, China, Belgium, Czech Republic (?), Germany, Italy(?), UK and the USA

• We will be working on making the NALTA network function as a unified system so that data can be shared and common standards set. Essentially NALTA could become a hyper-large area sparse array capable of looking at very large area and/or new cosmic ray phenomena.

• We expect NALTA to excite and interest new generations of physicists with an educational paradigm utilizing distributed interactive learning/research systems that can be adapted to many areas: the environment (air pollution measurements), geophysics (simple seismometers), meteorology (weather stations), etc.


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