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
James Pinfold Prague June 2004
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)
James Pinfold Prague June 2004
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
James Pinfold Prague June 2004
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
James Pinfold Prague June 2004
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
James Pinfold Prague June 2004
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
James Pinfold Prague June 2004
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
James Pinfold Prague June 2004
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
James Pinfold Prague June 2004
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:
James Pinfold Prague June 2004
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
James Pinfold Prague June 2004
Sensitivity of Future DetectorsSensitivity of Future Detectors
James Pinfold Prague June 2004
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 !!
James Pinfold Prague June 2004
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
James Pinfold Prague June 2004
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)
James Pinfold Prague June 2004
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)
James Pinfold Prague June 2004
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)
James Pinfold Prague June 2004
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
James Pinfold Prague June 2004
•~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
James Pinfold Prague June 2004
0.5 m2
Scint.
The ALTA Detector Systems GPS
The electronics readout
James Pinfold Prague June 2004
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
James Pinfold Prague June 2004
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
(
James Pinfold Prague June 2004
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
James Pinfold Prague June 2004
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
James Pinfold Prague June 2004
We Could Include Gravitational Wave We Could Include Gravitational Wave Detectors in the World Wide NetworkDetectors in the World Wide Network
James Pinfold Prague June 2004
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
James Pinfold Prague June 2004
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
James Pinfold Prague June 2004
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.
James Pinfold Prague June 2004
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.
James Pinfold Prague June 2004