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1 Henderson DUSEL Capstone 05 Henderson DUSEL Capstone 05 /06/2006 /06/2006 Background Modeling and Clean Background Modeling and Clean Room Design Considerations Room Design Considerations for HUSEP for HUSEP Zeev Shayer and Jonathan Ormes Zeev Shayer and Jonathan Ormes Department of Physics & Astronomy Department of Physics & Astronomy and Denver Research Institute and Denver Research Institute University of Denver University of Denver [email protected] [email protected]
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Page 1: 1 Henderson DUSEL Capstone 05/06/2006 Background Modeling and Clean Room Design Considerations for HUSEP Zeev Shayer and Jonathan Ormes Department of Physics.

11Henderson DUSEL Capstone 05/06/200Henderson DUSEL Capstone 05/06/20066

Background Modeling and Clean Background Modeling and Clean Room Design Considerations for Room Design Considerations for

HUSEPHUSEP

Zeev Shayer and Jonathan OrmesZeev Shayer and Jonathan OrmesDepartment of Physics & Astronomy Department of Physics & Astronomy

and Denver Research Instituteand Denver Research InstituteUniversity of DenverUniversity of Denver

[email protected]@du.edu

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The GoalThe Goal

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BackgroundBackground

What are Sources ?

• Cosmic Ray and Cosmic Activation• Natural Radioactivity from Rock• Natural Radioactivity in Materials• Radon in Air from U/Th decay series• Radioactive Dust• …..

How to get rid of it?

• Underground Laboratory• Passive and Active Shielding• Material Selection• Radon Trapping System (Ventilation) • Clean Room

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Simulation CodesSimulation Codes

SOURCES-4A/B Code

Input: Rock Composition

Output: Neutron Production Spectra (,n) & S.F.

MCNPXNeutron, Gamma and

Muon transport (no cascade)

+Point Depletion

FLUKA

Muon Transport and Particle Cascade

Calculations

GEANT4

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SOURCES-4A + MCNPXSOURCES-4A + MCNPX(Neutron and Gamma Background Plus Activation Analysis)(Neutron and Gamma Background Plus Activation Analysis)

• Homogenized Rock Composition For Henderson Mine (median, upper bound) ?

• Neutron Flux 1 – 3 x 10-6 n/s/cm2

• Average Energy 2.2 – 2.4 MeV

• ~70% (,n) and ~30% (S.F.)

• Reflection from walls ~20% enhancement

0.00E+00

5.00E-03

1.00E-02

1.50E-02

2.00E-02

2.50E-02

3.00E-02

3.50E-02

4.00E-02

4.50E-02

0 1 2 3 4 5 6 7 8 9 10

Neutron Energy (MeV)

Neut

ron

Prod

uctio

n Ra

te (n

orma

lized

)

(a,n)

S.F.

Page 6: 1 Henderson DUSEL Capstone 05/06/2006 Background Modeling and Clean Room Design Considerations for HUSEP Zeev Shayer and Jonathan Ormes Department of Physics.

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Examples of Shielding DesignExamples of Shielding Design

Parrafin

Lead

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Lead

LeadParaffin

Lead

Lead

• Lead-Paraffin is preferable (Case A) for exclusively neutron sources, as inelastic scattering in the lead is complemented by elastic scattering in hydrogen of the paraffin.

• Paraffin-Lead (Case B) is preferable for gamma-ray sources, as energetic gamma-rays scattered in the paraffin (Compton Effect) are rapidly absorbed by lead, which has particularly high absorption cross-section at low energies where the photo-electric effect predominates.

• Lead-Paraffin is preferable for reduction of the activation products produced in lead through the capture of neutrons

• Paraffin-Lead is preferable for reduction of secondary gamma-rays due to less gamma-ray produced through the inelastic scattering in lead and paraffin.

HAtoms/b/cm

Parrafin C25H52 0.0853

Polyethylene CH2 0.0789

Water H2O 0.0668

Page 8: 1 Henderson DUSEL Capstone 05/06/2006 Background Modeling and Clean Room Design Considerations for HUSEP Zeev Shayer and Jonathan Ormes Department of Physics.

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Neutron and Secondary Gamma Flux and their Neutron and Secondary Gamma Flux and their

attenuations propertiesattenuations properties

Configuration Case

Neutron Flux Secondary Gamma

Neutron Attenuation

Factor

Secondary Gamma

Production

No Shielding 22.728 1.321E-03 - -

A 4.99E-02 3.80 450 2880

B 1.01E-01 2.48E-02 225 19

C 6.37E-02 1.97E-01 357 149

D 5.10E-02 1.20E-01 445 91

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Performance of Various Shielding Block Cases Relative to the Performance of Various Shielding Block Cases Relative to the

“Homogenization” Case (Case D)“Homogenization” Case (Case D)

Reference Case D Neutron Attenuation Relative Factor (Case D/ Case #)

Gamma Ray Production Relative Factor (Case #/Case D)

D 1 1

A 0.99 32

B 2.25 0.21

C 1.25 1.64

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Gamma K-40Gamma K-40

Configuration Case K-40 Gamma Rays Attenuation Factor

A 264

B 673

C 693

D 686

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High Energy Charged ParticlesHigh Energy Charged Particles - Muon - Muon

• At sea level the muon flux is about

~120 – 140 muons/m2/s with mean energy of 4 GeV

• At 4000 mwe the muon flux is about

~1-3x10-4 muons/m2/s with mean energy of 250 GeV

About 106 Reduction Factor

Page 12: 1 Henderson DUSEL Capstone 05/06/2006 Background Modeling and Clean Room Design Considerations for HUSEP Zeev Shayer and Jonathan Ormes Department of Physics.

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Neutron Production by Muons from Rock and ShieldingNeutron Production by Muons from Rock and Shielding

Hadronic Cascade

Electromagnetic Cascade

Spallation Cascade

• The estimated neutron production from rock (from the literature) ~ 10-9 – 10-10 n/s/cm2

• Less than 3 orders of magnitude from U/Th chain production

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High Energy Charged ParticlesHigh Energy Charged Particles (100 GeV)– Protons (100 GeV)– Protons

((Neutron Production within shield materialNeutron Production within shield material))

1.00E+01

1.00E+02

1.00E+03

1.00E+04

40 50 60 70 80 90 100 110

Distance Within Shield (cm)

Neu

tro

ns

Flu

x (a

rbit

rary

un

its)

Case C

Case D

Case A

Case B

Shielded Block

B A

D

C

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Neutron energy spectra after 5 cm of the Neutron energy spectra after 5 cm of the

shield blockshield block

1.00E-02

1.00E-01

1.00E+00

1.00E+01

1.00E+02

1.00E+03

1.00E+00 1.00E+01 1.00E+02 1.00E+03

Neutron Energy (MeV)

Nu

mb

er

of

Ne

utr

on

s (

arb

itra

ry.

un

its

)

Case C

Case D

Case A

Case B

Case D1

D1

A

D

C

B

Page 15: 1 Henderson DUSEL Capstone 05/06/2006 Background Modeling and Clean Room Design Considerations for HUSEP Zeev Shayer and Jonathan Ormes Department of Physics.

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Optimization Methodology for Case D Optimization Methodology for Case D

(homogenized case)(homogenized case)

1.00E+00

1.00E+01

1.00E+02

1.00E+03

1.00E+04

1.00E+05

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Lead Weight Fraction

Att

en

ua

tio

n F

ac

tor

(ne

utr

on

&g

am

ma

)

Neutrons

2nd gamma

Gamma

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Optimization Methodology for Case D Optimization Methodology for Case D (homogenized case)(homogenized case)

1.00E+02

1.00E+03

1.00E+04

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Lead Weight Fraction

Ov

era

ll A

tte

nu

ati

on

Fa

cto

r

95%Neutrons+5%Gammas

50%Neutrons+50%Gammas

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SummarySummary

• Shielding and Clean Room Design

Detector components and shielding may become the dominant background Our shielding design approach is different from the ordinary one used in

underground laboratories (Lead and CH2 layers)

Easy to optimized for different detector options Less restriction on the contamination of lead with traces of Uranium/Thorium

Will need to specify the number of radon atoms per 1 m3 of air (1000?). (A typical room has around 105 particles/m3)

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SummarySummary

• It is possible to reduce the neutron and gamma from Henderson Mine by Factor of >105

• To reduce the neutron, gamma and from detector component 1. Ultra pure material down to ppt 2. Underground storage of important materials3. Underground assembly

• Neutrons from Muons1. Depth underground2. Active muon veto

• Radon induced neutron, gamma and 1. System for removing radon2. Ventilate volumes near detectors with radon free nitrogen


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