Stato dello sviluppo di un modulo ottico direzionale

1
Stato dello sviluppo di un modulo ottico
direzionale

• M.Taiuti
• NEMO COLLABORATION Meeting
• Catania 12/2/2007
• tratto da
• Meeting WP3
• PARIS 9/11/2006

2
Outlook

• Why a direction sensitive optical module?
• The simulation and related results
• A possible configuration
• How to proceed

3
Motivations

• Present solutions do not take into account the
  directionality of emitted Cherenkov light
• BUT ...
• Information on direction of the detected light
• improves the track reconstruction
• Reduces the background contribution

4
The simulation and related results

• The description of direction-sensitive OM has
  been implemented in the ANTARES software
• Sensitive area equal to the 10 PMT of ANTARES
• For simplicity the simulated OM recognizes 4
  different directions, i.e. solid angle has been
  divided into 4
• Reconstruction has been optimized
• See K.Fratini talk

5
Effective area
?? lt 2

• The KM3 with the NEMO-Tower configuration has
  been simulated
• Effective area and angular resolution improves at
  energies up to 10 TeV
• Improvement up to factor 2

?? lt 2
6
Point-like source detection

• Number of detected neutrinos from point-like
  sources increases by 20-25
• Evaluation of sensitivity still in progress
• Problem good efficiency also increase background!

• ? 2.5

7
A competitive design

• A KM3 detector equipped with directional PMTs
  provides at low neutrino energies the same
  performancies of a denser detector

8
The direction-sensitive OM

• A direction-sensitive optical module requires
• A position sensitive photo-detector
• A light collimation system
• A dedicated electronics

9
A. The position-sensitive photodetector

• Hamamatsu will provide a 10 prototype with 4
  anodes by end of Feb. 2007
• Photonis will provide similar prototype, the
  design is in progress
• Prototypes will be tested in Catania

10
B. The light collimator

• Spherical geometry allows an easy solution to the
  problem of efficiently collect the Cherenkov
  light
• Volume between mirrors must be filled with
  Plexiglas to match the refraction indexes

faz90
Side view
Side view
Intermediate view
faz45
faz0
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C. Read-out electronics

• Main requirements
• Simulations show that most of the time (gt80)
  only one sector gives signal
• Therefore it is not necessary to use 4 different
  amplifiers (this also improve the electronics
  signal-to-noise ratio)

1 hit 83 1 or 2 hits 97
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C. Read-out electronics

• Develop a dedicated electronics starting from
  present NEMO experience

Converter
Disc
Analog Sum
Converter
x 4
Disc
13
Optical Module conceptual design
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Summary

• Simulations show that information on the
  direction of the detected Cherenkov light improve
  the effective area at low energies
• The realization of a not-too-expensive direction
  sensitive optical module is feasible
• By the end of this year an optical module
  equipped with a prototype by Hamamatsu or
  Photonis will be available and tested