Transcript Slide 1

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
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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 Questions
• 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 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)?
James Pinfold
Prague
1/m2/s
“Knee”
1/m2/year
GZK
Cut-off
“Ankle”
1/km2/year
June 2004
Mysteries of the Spectrum
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Protons are trapped in our Galaxy (mG 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
GZK
land
1020 eV
James Pinfold
Prague June 2004
Acceleration of CRs above the Knee
• Up to the knee Fermi
acceleration (FA) in supernova
shock fronts can “explain”
the spectrum:
Emax ~RSNR x Z x B x bsh
The HILLAS Plot
• 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.
James Pinfold
Prague
June 2004
The Mysteries of an Opaque Universe
• 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 (n, 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.
James Pinfold
Prague June 2004
Region restricted
by GZK cut-off
~100 Mpc
10,000Mpc
Size of observable universe
Life Above the GZK Cut-off?
Fly’s Eye Big event
3 x 1020eV (50J!)
200 billion
particles
Many events observed
Above the GZK cut-off
AGASA (EAS ground
Array) seems to violate
The GZK cut-off
HI-RES (atmospheric.
fluorescence ) seems to
obey GZK theory
HI-Res.
+ AGASA
However both expts see
events with E > 1020eV
UHECRs as of 2001
GZK
Some debate as to
possible sources…
Some 6 doublets and 1
triplet of events have
been seen within 2o
cones
?
HiRes vs. AGASA
(410)x1019eV
> 1020 eV
James Pinfold
Prague
June 2004
Extended Air Showers
15 km
1016eV
Particle density
100m at ground level
Ne & Nm
correlation
Particles/m2
There are many ways of
detecting cosmic rays
James Pinfold
EAS properties can be used to estimate the
mass & energy of the incident particle using MC
Prague
June 2004
EAS -- the Atmosphere as a Calorimeter
Transverse profile
Longitudinal profile
• Fluorescence Detectors
– Atmosphere is sensing calorimeter
– Measure the longitudinal distribution
• Ground Arrays
– Technique developed in
the 50’s
Auger - measuring transverse &
– Measure the lateral distribution at
Longtudinal shower profiles
ground
James Pinfold
Prague
June 2004
Measuring EASs
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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 Worldwide
Expts in space
Atmospheric flour.
2 site 14 km apart
100 detector
surface array
EUSO or OWL
Artists impression
Cerenekov telecopes
Ice cerenkov
1600 water det.
4 atm. fluor. det.
James Pinfold
Prague June 2004
Sensitivity of Future Detectors
James Pinfold
Prague
June 2004
Tantalizing Hints of Non-random
Cosmic Ray Phenomena
• The Japanese LAAS array(2000), 8 stations sep. by ~50 km.
– Anisotropy of successive air showers – within a Dt 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 4.8s (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
Networks
• 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 (DX 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
James Pinfold
Prague
Dt
June 2004
Experimental 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
Cosmic 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 Array
(First results 1999)
Okiyama University
Typically very small air
showers arrays (10x10 m2)
with about 8 detectors
(0.25 m2) at each site.
James Pinfold
Prague June 2004
Sparse Very Large Area Networks 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 Time
Coincidence Arrays (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
~100 detector systems
• SCROD – Northeastern University
Across North America
• TECOSE – University of Texas
• WALTA – University of Washington
• MEXICO – Groups around Mexico city
James Pinfold
Prague
June 2004
ALTA The 1st
Example of a Sparse
Large Area
“Educational” Array
Network
•~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
James Pinfold
Prague
June 2004
The ALTA Detector Systems
GPS
The electronics readout
0.5 m2
Scint.
James Pinfold
Prague
June 2004
The 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
3 x
• TOTAL
1 x
1 x
~ 10,000 EUR
1 x
Data
GPS Receiver & acquistion
electronics
computer
Readout Electronics
Properties 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.
James Pinfold
Prague June 2004
Average size
Of a 1014 ev shower
10m
First 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
James Pinfold
Prague
Local coincidence rate
Atmospheric pressure
(
June 2004
North American Large Area Time
Coincidence Arrays (NALTA)
CANALTA
CANALTA
BC-ALTA ALTA
CANALTA
CANALTA
CANALTA
WALTA
CROP
SCROD
CosRayHS
CosRayHS
SALTA
CosRayHS
CHICOS
TECOSE
Mexico City, etc.)
CosRayHS
Detectors in place
In preparation
In planning
James Pinfold
Prague
June 2004
An Example of a Proposed Array in Italy –
EEE (Extreme Energy Event 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
Experiments Worldwide
Internet based “ALTA” arrays in schools could be networked
with the World’s largest Cosmic Ray detector system
ALTA
CANALTA
NALTA
James Pinfold
“ALTA” type
projects in;
1) Czeck Republic (planning)
2) Germany,
3) Italy (planning)
4) Denmark
Prague
June 2004
We Could Include Gravitational Wave
Detectors in the World Wide Network
James Pinfold
Prague
June 2004
ALTA “Hand on” Workshop Nov. 2001
• Workshop held as introduction to the physics as well as hands on
training with detectors.
The crowded workshop
area
At the U of Alberta
Alberta high-school
James Pinfold
Prague
June 2004
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.
James Pinfold
CROP Workshop Participants
July 2000
Prague June 2004
The 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
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 & 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