status of neutron simulations piotr mijakowski (warsaw) ardm meeting, 2010/12/03 1

Status of neutron simulations

Piotr Mijakowski (Warsaw) ArDM meeting 20101203

1

Outline

PMijakowski 2ArDM meeting 3 Dec 2010

bull Updated results on rock neutron simulation at CANFRANC

ndash run simulation on a computer cluster with Geant 493

ndash 2 tested configurations

(1)with 2 holes in the shield 30 cm diameter each hole 50 cm thick shield

(2) no holes (50 cm of polyethylene)

50 cm

50 cm

50 cm

Energy spectrum of rock neutrons

3

energy spectrum of neutrons at rockface ndash input for simulation

parametrizatio

n

MJ Carson JC Davies et al

Astroparticle Physics 21(2004)

PMijakowski 3

rock ~ 38 times 10-6 n(scm2)

flux CANFRANC (old hall)

JM Carmona et al hep-ex0403009

ArDM meeting 3 Dec 2010

PMijakowski 4

with holes wo holes

generated events 37times108 15 times 109

livetime 265725 days(637739 hours)

106767 days(256241 hours)

events which hit shield ~55k per hour ~55k per hour

events which get inside holes in the

shield ~237 per hour -

events which get through the shield and hit detector

external container

22869 evts

359 plusmn 02 per hour(8606 plusmn 57 per day)

above 100 keV

41 plusmn 01 per hour

70 evts


above 100 keV (9 evts)

008 plusmn 003 per day

events which get inside active

volume(not unique)



50 cm thick polyethylene shield with bottom and top lid of 50 cm heighttwo cylindrical holes in the shield of a 30 cm diameter each


all errors statistical only

these evts are stored in NTUPLE

NO SHIELD 12k evts per hour hit external container

WITH SHIELD amp NO HOLES

~5 times105 neutron flux reduction container

WITH SHIELD amp WITH HOLES

~3times102 neutron flux reduction container

PMijakowski

with holes- neutrons at external container

5

156m

1098 m

r =73 m

zy

403 m

29 mzx


X y z

top lid is flat

NTUPLE parametrs of neutrons stored at the entrance of ArDM external container

external container diameter = 1112 m

PMijakowski

no holes- neutrons at external container

6

156m

1098 m

r =73 m

zy

403 m

29 mzx


X

external container diameter = 1112 mArDM meeting 3 Dec 2010

zy

PMijakowski

Neutrons at external container

7

Energy at external container

13 (9 neutrons) above 100 keV


12 neutrons above 100 keV

WITH HOLES NO HOLES

Would expect for neutrons above 100 keV

008 nday ~004 nday (interact) ~002 nday (multiple scattering)no holes

41 nhour ~2 nhour (interact) ~1 nhour (multiple scattering)with holes

PMijakowski

Summary amp Plan

bull thickness of the shield seems to provide sufficient protection against neutrons from rock radioactivity

bull holes are a bit of a problem

8

Summary

Plan

bull pass the codes and ntuples to the groupbull (dedicated simulation of neutrons stored at external

container ndash investigate multiple scattering interactions etc)


BACKUP

PMijakowski ArDM meeting 3 Dec 2010

Rock neutron simulation in Geant4

bull 50 cm thick cylindrical polyethylene shield

10

bull 2 cylindrical transmission holes on side (filled with air)

50 cm

50 cm

50 cm

Ilustr 3 MeV neutron coming from the wall

bull Neutrons related to radioactivity in rock simulated on all planes of CANFRANC hallndash 2m of concrete around the hall

is also included (backscattering)

30 cm diameter each

bull Continous energy spectrum of neutronsat rock surface

hellip NEXT SLIDE

PMijakowski

PREVIOUS - WRONG LIVE-TIME CALCULATION

11ArDM meeting 29 Oct 2010

with holes wo holes

generated events 7082 times 106 7 times 106

livetime [hour] 57 h 1min 56 h 22 min

events which hit shield689379

~12k per hour686312

~12k per hour

events which get inside holes in the shield

2994~525 per hour

-


external container

448~79 per hour

0

events which get inside active volume

190~33 per hour

0


Slide 1

Slide 2


Slide 4




Summary amp Plan

Slide 9



Outline

PMijakowski 2ArDM meeting 3 Dec 2010

bull Updated results on rock neutron simulation at CANFRANC

ndash run simulation on a computer cluster with Geant 493

ndash 2 tested configurations

(1)with 2 holes in the shield 30 cm diameter each hole 50 cm thick shield

(2) no holes (50 cm of polyethylene)

50 cm

50 cm

50 cm


3


parametrizatio

n



PMijakowski 3





PMijakowski 4

with holes wo holes



106767 days(256241 hours)





external container

22869 evts


above 100 keV


70 evts





volume(not unique)












PMijakowski


5

156m

1098 m

r =73 m

zy

403 m

29 mzx


X y z

top lid is flat



PMijakowski


6

156m

1098 m

r =73 m

zy

403 m

29 mzx


X


zy

PMijakowski


7





WITH HOLES NO HOLES




PMijakowski

Summary amp Plan



8

Summary

Plan




BACKUP




10


50 cm

50 cm

50 cm




30 cm diameter each


hellip NEXT SLIDE

PMijakowski



with holes wo holes




~12k per hour686312

~12k per hour


2994~525 per hour

-


external container

448~79 per hour

0


190~33 per hour

0


Slide 1

Slide 2


Slide 4




Summary amp Plan

Slide 9




3


parametrizatio

n



PMijakowski 3





PMijakowski 4

with holes wo holes



106767 days(256241 hours)





external container

22869 evts


above 100 keV


70 evts





volume(not unique)












PMijakowski


5

156m

1098 m

r =73 m

zy

403 m

29 mzx


X y z

top lid is flat



PMijakowski


6

156m

1098 m

r =73 m

zy

403 m

29 mzx


X


zy

PMijakowski


7





WITH HOLES NO HOLES




PMijakowski

Summary amp Plan



8

Summary

Plan




BACKUP




10


50 cm

50 cm

50 cm




30 cm diameter each


hellip NEXT SLIDE

PMijakowski



with holes wo holes




~12k per hour686312

~12k per hour


2994~525 per hour

-


external container

448~79 per hour

0


190~33 per hour

0


Slide 1

Slide 2


Slide 4




Summary amp Plan

Slide 9



PMijakowski 4

with holes wo holes



106767 days(256241 hours)





external container

22869 evts


above 100 keV


70 evts





volume(not unique)












PMijakowski


5

156m

1098 m

r =73 m

zy

403 m

29 mzx


X y z

top lid is flat



PMijakowski


6

156m

1098 m

r =73 m

zy

403 m

29 mzx


X


zy

PMijakowski


7





WITH HOLES NO HOLES




PMijakowski

Summary amp Plan



8

Summary

Plan




BACKUP




10


50 cm

50 cm

50 cm




30 cm diameter each


hellip NEXT SLIDE

PMijakowski



with holes wo holes




~12k per hour686312

~12k per hour


2994~525 per hour

-


external container

448~79 per hour

0


190~33 per hour

0


Slide 1

Slide 2


Slide 4




Summary amp Plan

Slide 9



PMijakowski


5

156m

1098 m

r =73 m

zy

403 m

29 mzx


X y z

top lid is flat



PMijakowski


6

156m

1098 m

r =73 m

zy

403 m

29 mzx


X


zy

PMijakowski


7





WITH HOLES NO HOLES




PMijakowski

Summary amp Plan



8

Summary

Plan




BACKUP




10


50 cm

50 cm

50 cm




30 cm diameter each


hellip NEXT SLIDE

PMijakowski



with holes wo holes




~12k per hour686312

~12k per hour


2994~525 per hour

-


external container

448~79 per hour

0


190~33 per hour

0


Slide 1

Slide 2


Slide 4




Summary amp Plan

Slide 9



PMijakowski


6

156m

1098 m

r =73 m

zy

403 m

29 mzx


X


zy

PMijakowski


7





WITH HOLES NO HOLES




PMijakowski

Summary amp Plan



8

Summary

Plan




BACKUP




10


50 cm

50 cm

50 cm




30 cm diameter each


hellip NEXT SLIDE

PMijakowski



with holes wo holes




~12k per hour686312

~12k per hour


2994~525 per hour

-


external container

448~79 per hour

0


190~33 per hour

0


Slide 1

Slide 2


Slide 4




Summary amp Plan

Slide 9



PMijakowski


7





WITH HOLES NO HOLES




PMijakowski

Summary amp Plan



8

Summary

Plan




BACKUP




10


50 cm

50 cm

50 cm




30 cm diameter each


hellip NEXT SLIDE

PMijakowski



with holes wo holes




~12k per hour686312

~12k per hour


2994~525 per hour

-


external container

448~79 per hour

0


190~33 per hour

0


Slide 1

Slide 2


Slide 4




Summary amp Plan

Slide 9



PMijakowski

Summary amp Plan



8

Summary

Plan




BACKUP




10


50 cm

50 cm

50 cm




30 cm diameter each


hellip NEXT SLIDE

PMijakowski



with holes wo holes




~12k per hour686312

~12k per hour


2994~525 per hour

-


external container

448~79 per hour

0


190~33 per hour

0


Slide 1

Slide 2


Slide 4




Summary amp Plan

Slide 9



BACKUP




10


50 cm

50 cm

50 cm




30 cm diameter each


hellip NEXT SLIDE

PMijakowski



with holes wo holes




~12k per hour686312

~12k per hour


2994~525 per hour

-


external container

448~79 per hour

0


190~33 per hour

0


Slide 1

Slide 2


Slide 4




Summary amp Plan

Slide 9






10


50 cm

50 cm

50 cm




30 cm diameter each


hellip NEXT SLIDE

PMijakowski



with holes wo holes




~12k per hour686312

~12k per hour


2994~525 per hour

-


external container

448~79 per hour

0


190~33 per hour

0


Slide 1

Slide 2


Slide 4




Summary amp Plan

Slide 9



PMijakowski



with holes wo holes




~12k per hour686312

~12k per hour


2994~525 per hour

-


external container

448~79 per hour

0


190~33 per hour

0


Slide 1

Slide 2


Slide 4




Summary amp Plan

Slide 9



status of neutron simulations piotr mijakowski (warsaw) ardm meeting, 2010/12/03 1

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