Top Banner
CALIBOB Ciro Bigongiari
21

Calibob

Feb 22, 2016

Download

Documents

qamra

Ciro Bigongiari. Calibob. Schematic View. Optical Module. Sea water . Optical Beacon. Photon Path. History. Calibob was derived from KM3 code It was written in f90 language It was recoded in f77 transforming all structures in common blocks (No need of f90 compiler) - PowerPoint PPT Presentation
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Page 1: Calibob

CALIBOB

Ciro Bigongiari

Page 2: Calibob

Ciro Bigongiari 2

Schematic View

17/05/2011

Photon Path

Optical Beacon

Optical Module

Sea water

Page 3: Calibob

Ciro Bigongiari 3

History

Calibob was derived from KM3 code It was written in f90 language It was recoded in f77 transforming all

structures in common blocks (No need of f90 compiler)

On the assumption that the simulated light sources are nearly monochromatic all the dependencies on the wavelength were removed La, Ls, β(θ) and n didn’t depend on λ

Recently reintroduced the dependence on λ of La, Ls and n trying to improve the Data-MC agreement17/05/2011

Page 4: Calibob

Ciro Bigongiari 4

LED Spectrum

17/05/2011

From AVAGO CB30 Datasheet

Peak wavelength 470 nm

Sigma 15nm

Slightly asymmetric Values confirmed by measurements in Valencia labANTARES LED

Page 5: Calibob

Ciro Bigongiari 5

Code structure (I)

Three step package: GEN, HIT, CAL GEN

Simulates photon emission and photon propagation through sea water up to a maximum distance (350 m)

No absorption simulated at this stage Photon position, direction, transit time and

wavelength on 34 spherical shells (10 m step) centred on the light source are recorded

Some more histograms and ntuples saved for debugging purposes

17/05/2011

Page 6: Calibob

Ciro Bigongiari 6

Code structure (II) Three step package: GEN, HIT, CAL

HIT Simulates absorption by weighting photons

Weight = exp(-PhotonPath/AbsorptionLength) Simulates photon detection by an optical module at

different position/direction w.r.t. to the optical beacon Stores detection probability tables

CAL Reads in detector geometry Loops over OB flashes and optical modules Stores hits in ASCII format

17/05/2011

Page 7: Calibob

Ciro Bigongiari 7

Optical Beacons Light emission from point-like light sources

Angular distribution of emitted photons Uniform Cleaved LED Laser + Glass Rod

Time distribution of emitted photons Gaussian LED pulse

Wavelength distribution of emitted photons Gaussian LED spectrum

17/05/2011

Page 8: Calibob

Ciro Bigongiari 8

Optical Modules

Photon detection by optical modules is simulated exactly in the same way as in KM3 Angular acceptance Glass transmission Gel transmission Photo-conversion efficiency

17/05/2011

Page 9: Calibob

9

Sea Water (I)

Absorption: Absorption is simulated by weighting

photons The absorption length is calculated

rescaling the Smith&Baker parameterization

17/05/2011Ciro Bigongiari

)ker(/)ker(* ReRe ffa SmithBaSmithBaLL

WARNING: in this way LA can be larger than SmithBaker(λ) which should be an upper limit (pure water).

Page 10: Calibob

Ciro Bigongiari 10

Absorption length

17/05/2011

λRef = 470 nm LRef = 60 m

Page 11: Calibob

Ciro Bigongiari 11

Sea Water (II)

Scattering: The scattering length is calculated rescaling

the Kopelevich parametrization with Vs = Vl = 0.1

17/05/2011

)(/)(* ReRe fsfs KopelevichKopelevichLL

3.07.13.4 )550(**3120.0)550(**3400.1)550(*0017.0)(

nmVnmVnmKopelevich LS

The values of VS and VL presently used are different from the ones used in KM3 which are outside the allowed region (Mobley )

Page 12: Calibob

Ciro Bigongiari 12

Scattering Length

17/05/2011

Page 13: Calibob

Ciro Bigongiari 13

Sea Water (III) Refraction Index:

The refraction index is a function of photon wavelength and water temperature, pressure and salinity. We fixed

T = 13.1 ºC P = 220 bar S = 38.44 %0

17/05/2011

32 )1(*)1(*1*)(

DCBAnPhase )(*1)()( '

Phase

PhaseGroup n

nn

A = 1.3201 B = 16.2561 C = -4382.0 D = 1.1455e6

Page 14: Calibob

Ciro Bigongiari 14

Refraction Index

17/05/2011

Page 15: Calibob

Ciro Bigongiari 15

Sea Water (IV)

Volume Scattering Function: β = β(θ,λ) is a function of scattering angle and photon

wavelength The dependence on λ has not be considered so far

β = β(θ) Usually we use the so-called PARTIC model

17/05/2011

)(*)1()(*)( Petzoldw

WARNING: Petzold’s measurements were performed at 514 nm

Page 16: Calibob

16

Scattering Angle

17/05/2011Ciro Bigongiariη = 0.17 <cos(θ)> = 0.767

Page 17: Calibob

Ciro Bigongiari 17

Volume Scattering Function

17/05/2011

V.H

altr

in

Appl

.Opt

.38(

33)-

1999

Page 18: Calibob

Ciro Bigongiari 18

Comparison

17/05/2011

New

Old

Page 19: Calibob

Ciro Bigongiari 19

Summary & Outlook

Reintroduced absorption length, scattering length and refraction index dependence on wavelength

No big improvement found. To be investigated further

Dependence of volume scattering function still to be implemented.

Continue comparison with KM3

17/05/2011

Page 20: Calibob

Ciro Bigongiari 20

Water Models

There are some recently developed water models with a reasonably low number of parameters. For example Kopelevich’s Haltrin’s Morel’s Zege – Katsev – Prikcach

Should we try a more recent water model ? Can they be used for very deep waters ?

17/05/2011

Page 21: Calibob

Ciro Bigongiari 21

Smith&Baker ?

17/05/2011

…………………………In the visible part of the spectrum, recent studies from Sogandares and Fry (1997) and Pope and Fry (1997), based on different measuring techniques, provided very precise measurements of pure water absorption from 380 to 700 nm. The results obtained by these authors emphasized that Smith and Baker (1981) formulation strongly overestimated the actual aw(λ) in particularly below 490 nm. At 380 nm Pope and Fry (1997) values are about 2 times lower.Such differences between Smith and Baker (1981) and Pope and Fry (1997) formulations have been attributed to biases in the former measurements induced by organic impurities absorption and scattering effects. Moreover, Pope and Fry (1997) confirmed the existence of seventh and eighth harmonics of the OH stretch at 449 and 401 nm and the presence of the absorption minimum at 420 nm as previously observed by Sogandares and Fry (1997). The data by Pope and Fry (1997) are currently considered as the reference value and are widely used in bio-optical modeling and remote sensing applications in the visible………(Vantrepotte&Mélin2006).