Oct 29, 2009 1 P. Bhat, N. Mokhov, A. Singh

Radiation Simulations in CMS

Pushpa Bhat, Nikolai Mokhov, Anil Singh*Fermilab

Batavia, IL

* Panjab Univ., India

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● Latest round of efforts – Started in 2007, to re-evaluate beam-induced radiation in CMS,

particularly in the pixel detector due to concerns of safety in typical beam-accident scenarios – e.g., single module abort kicker prefire initiating asynchronous beam abort

● Scenarios Studied– pp collisions at L=1034 cm2sec-1

– Machine-induced Backgrounds: beam-gas, beam halo

– Beam Accidents (potentially the most risky)

● Simulation Results: Maps and tables of radiation dose, particle fluence, energy spectra are available. Results in (r,z) stored in a database. Web Tool exists to extract numbers. Over a dozen presentations given at CMS mtgs.

● CMS Notes: CMS CR-2009/262 (pp results conf rep for tracker) CMS Note-2009/000 (Beam accident studies) Detailed CMS Note on pp results in preparation

MARS Simulation Studies

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MARS Model

HBHE

BCS BCM1

The Detector

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CMS:MARS MODEL

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Radiation Dose (Gy/s)@L= 1034cm-2 s-1

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Absorbed Dose (50 fb-1)

105

104

103

102

10

1

10-1

10-2

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Comparison with TDR results

105

104

103

102

10

1

10-1

10-2

Note: Overlaid contours (TDR; Mika H) are for 500 fb-1 while the bottom plot (MARS, this study) is for 50 fb-1

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HCAL (including HF)

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Absorbed Dose

R

HBHE

2E-4 Gy/s 1MRad / 500 fb-1

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Neutron Fluence

HB HE

R

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Charged Hadron Fluence

R

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HF Region

Max. Dose >100x than in HE

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Dose/Fluence Web Calculator

Returns results for a given radius, z and L.dt using data in a database

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● The database and the tool are being extended.

Dose/Fluence Web Calculator

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Dose (Gy) 100 fb-1

Finer granularity

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Summary

● Extensive radiation simulations have been done for the CMS detector, over the past few years using MARS15.

– pp at 14 TeV, 10 TeV, 3.8T, 0T

– preliminary beam-gas, beam-halo

– Beam accidents

● Lots of results and tools exist!

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Extra Slides

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