California HIgh school Cosmic ray ObServatory

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California HIgh school Cosmic ray ObServatory

• A collaboration of Los Angeles area universities,
  colleges, and schools to study ultra-high energy
  cosmic rays with an array of detectors.

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California HIgh school Cosmic ray ObServatory

• Project Director
• Prof. Robert McKeown
• (Kellogg Radiation Lab, Caltech)
• Education Director
• Prof. Royichi Seki
• (Dept. of Physics, CSU Northridge)
• Project Coordinator
• Dr. Theresa Lynn
• (Kellogg Radiation Lab, Caltech)

• Also at Caltech
• Dr. Chris Jillings
• Elina Brobeck
• Brant Carlson

• CHICOS is affiliated with
• Caltech
• CSU - Northridge
• UC Irvine

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What are cosmic rays?

• Cosmic rays are charged particles (protons,
  electrons, atomic nuclei) or gamma rays
  (high-energy photons)
• The sun is the primary source of low-energy
  cosmic rays
• High-energy cosmic rays may originate in
  supernovae, active galactic nuclei, or other
  astrophysical phenomena

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Discovery of Cosmic Rays

• Victor Hess measured cosmic rays from a hot air
  balloon
• Discovered radiation increases with altitude
• Awarded the Nobel prize in 1936

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The CHICOS Detector Array
San Fernando Valley 26 sites active
San Gabriel Valley 28 sites active
Los Angeles Area 2 sites in progress others
interested
Total 54 active sites Plus 9 temporary
active sites at Caltech (the CHIQUITA array)
Goal 90 active sites in the CHICOS Array by 2005.
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Energy Spectrum
Sun
CHIQUITA showers (Caltech Array)
Supernovae
Single particle hits in CHICOS detectors (200
per sec.)
CHICOS showers (San Gabriel and San
Fernando Arrays)
AGN, GRBs, etc. ?
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CHICOS Detectors in Schools

• Each school in the array has two detectors
  (shmoos) on the roof.
• We provide a computer which records the data and
  sends files to Caltech each day.
• A teacher contact in each school helps us keep
  the site running smoothly.

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CHICOS Detector Site Layout
Shmoo Design
PMT
Computer
CEU
proton
light
Scintillator
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CHICOS Hardware
CEU
High Voltage Supply
Photo- Multiplier Tube

• The shmoos were donated by Los Alamos National
  Laboratory.
• Other hardware is made and assembled at Caltech.

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Summer Lab Program

• Two years so far, 7-8 weeks each year.
• 1 teacher and 2-4 students each week.
• Students build control circuits and assemble and
  test CHICOS hardware.
• Seminars, lunches and campus tours.

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Screen Capture of CHICOS software
Coincidences and Triggers
Single Hits
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CHICOS Data Collection

• At Caltech
• Triggers from all sites are combined into a
  master file.
• The trigger file is sent back to all sites in the
  array, which check for matching events in the A
  and B data.
• Match files are sent back to Caltech, and
  combined into time-ordered lists of nearly
  simultaneous events across the array.
• These lists are filtered to identify possible
  cosmic ray airshowers.

Detector A 200 hits/sec
Detector B 200 hits/sec
Coincidences 25 per minute
Triggers 0-5 per min
Caltech Master File
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Sample CHICOS Data from May 13, 2003 Trigger
Site Westridge
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Reconstruction Energy 5.3 x 1018 eV
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Current CHICOS Results

• More than 10 ultra-high energy CHICOS showers in
  the last year of operation.
• Over 500 low energy CHIQUITA showers

of showers
Log Energy (eV)
ALL data is available online at
www.chicos.caltech.edu for participating schools!
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CHICOS Projects for Students

• Analysis of CHICOS cosmic-ray airshowers, at
  either high or low energies. All tools are
  online.
• Observing the variability in detector rates with
  changes in weather (temperature, humidity, etc.)
  and solar activity (such as large solar flares).
• These projects involve students in real research
  and their contributions are important to the
  CHICOS project.
• More classroom activities are under development,
  and suggestions are welcome!

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Future Research with CHICOS

• Sky map of UHECRs to look for clustering.
• Recording enough UHECRs to determine if the
  spectrum extends beyond 1020 eV.

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www.chicos.caltech.edu