1. Electron Beam as a standard candle for EHECR air shower
Feb.26th, 2004
Kashiwa
Masaki Fukushima / ICRR

2. Efficiency of Air Fluorescence
Total Absorption Calorimetry by AF ：　 Meas. of Absolute Energy
2. Atmospheric
Correction
1. Scintillation
Efficiency
Loss in the transmission
DE > # of photons
3. Telescope Parameters
Mirror
Window
Filter
PMT QE+CE
Electronics Gains
Efficiency of Air Fluorescence
# of photons > ADC ch.
Biggest Headache：　No Calibration
Source to Determine Absolute Energy Scale

3. LE Electron Beam as Air Fluorescence Calib. Source
Bulk of air shower E loss by LE electrons / γ’s
40 MeV electron x 109 particles ~ 4 x 1016 eV
Critical energy ~ 95 MeV
After 30 m air, ΔE~7 MeV,
mult.scatt. ~ 100 mrad
Cherenkov threshold ~ 25 MeV
Shoot electron beam up in the sky 100 m away
from the station.
( equiv. to 4 x 1020 eV shower 10 km away)

4. ・ Distortion of focus and
Horizontal
Position Scan
about < 50m
Problems?
・　Distortion of focus and
　　acceptance.
・　CAMERA dead zones.
　　> angular steering
> horizontal scan
・　Cherenkov light?
>>>　precise MC possible
for 40 MeV photons
by GEANT/EGS
100m away
LINAC BEAM
67m high
Small Anglular
Steering
LINAC BEAM
100m away

5. GEANT Simulation by Sakurai.
20 MeV
40 MeV
100 m away
Telescope FoV
FoV of
1 PMT
~100k pe
/ PMT
From Energy Loss to ADC ch.
AF Source of Known Total Energy. End-to-End Calib.

6. Requirements for the Accelerator
　Energy：　１０－４０　MeV, variable
　Intensity：　１０ ９ electrons　/　pulse, variable
　Pulse Width：　１－１０　μs
　Repetition：　～ １ Hz
　Beam Size：　～１０ ｍｍ φ
　Beam Spread：　～１ mrad
　Accuracy of Energy x # of particles：　～１％
　small, stable and low power　（desert spec.）
　portable

7. Microtron idea ・ compact injector for SR ・ high energy possible
6 MeV linac
・ compact injector for SR
・ high energy possible
・ accurate energy
・ energy stepping

8. Linac idea ・ medical linacs with 20 MeV or less
C band acc. structure
S band acc. structure
Klystron
Pulsed Power
Supply
・ medical linacs with 20 MeV or less
・ 5 GHz system for LC study at KEK (40 MeV/m reached)
・ magnetic energy analyzer required
・ very compact but magnet + Klystron is heavy

9. Measuring together with Laser Candle for atmosph. transparency
monitoring
Rayleigh scatt.
Known x-section
ETOT / hν
= # of photons
10 mJ
~ 1016photons
１００ｍ
１０ ｋｍ

10. Working with Laser Candle
Reach of Lidar
（< 20 km）
Laser Candle
Linac Candle

11. Summary: Electron Beam as AF Calibration Source
Absolutely calibrated AF source
The idea survived initial inspections
Working examples; FLASH and Super-K Linac calib.
Standard beam technologies
Adaptation to “desert” environment required.
Very low dose, but rad. protection must be assured.
~ 2 years and ~ 1M$ for construction
Help and expertise at KEK and US acc. Lab.