[email protected] blm review mario santana leitner outlook on fluka simulations for...

[email protected]@slac.stanford.eduBLM review

Mario Santana Leitner

OUTLOOK ON FLUKA SIMULATIONS FOR UDULATOR DAMAGE AND BLM

RESPONSE

Mario Santana Leitner, Alberto Fassò

and Joachim VollaireRadiation Protection Department

Stanford Linear Accelerator Center

LCLS Beam Loss Monitor Preliminary Design ReviewSLAC, January 24, 2008


Mario Santana Leitner- 2 / 18 -

Outline

Characterization of demagnetization under radiation

fields

Radiation showers along the undulator

Beam loss monitor response and correlation to losses in

the undulator



FLUKA geometrySLAC Experiment

(9 Nd-Fe-B Samples, 13.7-GeV electron)

Characterization of the demagnetizationLCLS Permanent Magnet Damage Study; experiment T493

Experiment spokesman: by

Heinz-Dieter Nuhn



1. Dose calculated and demagnetization measured are for the whole sample2. Difference between forward and side samples

Characterization of the demagnetizationMeasured Damage Not Proportional to Dose



Sample 1 Neutron fluence in all samples

Characterization of the demagnetizationDose Fraction and Neutrons



Characterization of the demagnetizationMapping of 2-D Neutron Fluence in Samples



Characterization of the demagnetizationMapping of Measurement of 2-D Demagnetization

Demagnetization

measurements analyzed

by Heinz-Dieter Nuhn



Characterization of the demagnetizationNew 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



LCLS model including detailed

description of the segments, dumps,

magnets, magnetic fields, etc.

BLM array just introduced.

Radiation showers along the undulatorFLUKA model of LCLS



Radiation showers along the undulatorMagnetic field test. Electron transport.

30 micron

displacement in X or

Y plane.

Further analysis

ongoing…



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.

Since

Biasing destroys correlations: therefore for this option it is necessary to run FLUKA in analog mode.



FLUKA features for BLM simulationsCommand 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

Since

Biasing destroys correlations: therefore for this option it is necessary to run FLUKA in analog mode.



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.

FLUKA features for BLM simulationsQuenching and Optical Photons

[email protected] blm review mario santana leitner outlook on fluka simulations for...

Documents