Transcript Fluka Simulations

OUTLOOK ON FLUKA SIMULATIONS
FOR UDULATOR DAMAGE AND BLM
RESPONSE
Mario Santana Leitner, Alberto Fassò
and Joachim Vollaire
Radiation Protection Department
Stanford Linear Accelerator Center
LCLS Beam Loss Monitor Preliminary Design Review
SLAC, January 24, 2008
BLM review
Mario Santana Leitner
[email protected]
Outline
Characterization of demagnetization under radiation
fields
Radiation showers along the undulator
Beam loss monitor response and correlation to
losses in the undulator
BLM review
Mario Santana Leitner
- 2 / 18 -
[email protected]
Characterization of the demagnetization
LCLS Permanent Magnet Damage Study; experiment T493
Experiment spokesman: by
Heinz-Dieter Nuhn
FLUKA geometry
BLM review
Mario Santana Leitner
SLAC Experiment
(9 Nd-Fe-B Samples, 13.7-GeV electron)
[email protected]
Characterization of the demagnetization
Measured Damage Not Proportional to Dose
1. Dose calculated and demagnetization measured are for the whole sample
2. Difference between forward and side samples
BLM review
Mario Santana Leitner
[email protected]
Characterization of the demagnetization
Dose Fraction and Neutrons
Sample 1
BLM review
Mario Santana Leitner
Neutron fluence in all samples
[email protected]
Characterization of the demagnetization
Mapping of 2-D Neutron Fluence in Samples
BLM review
Mario Santana Leitner
[email protected]
Characterization of the demagnetization
Mapping of Measurement of 2-D Demagnetization
Demagnetization
measurements analyzed
by Heinz-Dieter Nuhn
BLM review
Mario Santana Leitner
[email protected]
Characterization of the demagnetization
New FLUKA simulations to match demagnetization grid
The geometry of the magnets has been re-written to
match the detector scoring with the virtual sub-regions
- 800 detectors for the fluence
- Region bin-size 2mm x 2mm
Simulations to be sent now
Analysis of the results requires some time
BLM review
Mario Santana Leitner
[email protected]
Radiation showers along the undulator
FLUKA model of LCLS
LCLS model including detailed
description of the segments,
dumps, magnets, magnetic
fields, etc.
BLM array just introduced.
BLM review
Mario Santana Leitner
[email protected]
Radiation showers along the undulator
Magnetic field test. Electron transport.
30 micron
displacement in X
or Y plane.
Further analysis
ongoing…
BLM review
Mario Santana Leitner
[email protected]
BLM response simulation and
correlation to losses in the undulator
BLM coarse geometric implementation done.
- Array of BLM’s at 40 cm from following segment
- thin W radiator in the front. What should be the thickness?
- What is the thickness of the aluminum wall in the inner
surfaces?
FLUKA scoring subroutines to be written.
Other FLUKA options to be examined.
Biasing destroys correlations: therefore for this option it is necessary to run
FLUKA in analog mode.
S
BLM
i review
Mario
n Santana Leitner
[email protected]
FLUKA features for BLM simulations
Command DETECT
We call an "event" the energy deposited in a user-defined set of one or
more DETECTOR REGIONS by one primary particle and by its
secondaries.
We call a "signal" the energy deposited in a user-defined set of one or
more TRIGGER REGIONS by the same primary particle and secondaries.
Output: a distribution of energy deposited per event in the DETECTOR
REGIONS in coincidence with a signal larger than a pre-defined cut-off
Possible application:
to find correlations between dose in BLM and dose in a set of magnets
Biasing destroys correlations: therefore for this option it is necessary to run
FLUKA in analog mode.
S
BLM
i review
Mario
n Santana Leitner
[email protected]
FLUKA features for BLM simulations
Quenching and Optical Photons
QUENCHING: FLUKA can calculate energy deposition
in scintillators corrected for quenching, applying the
Birks law.
This can allow to predict the correct BLM response in
a mixed radiation field of photons, neutrons and other
particles
OPTICAL PHOTONS: FLUKA can also produce and
transport scintillation light if the user provides the
wavelength.
BLM review
Mario Santana Leitner
[email protected]