juas 2010 – p. berkvens, radiation & safety 1/95 radiation and safety p. berkvens 1.radiation...

JUAS 2010 – P. Berkvens, Radiation & Safety

1/95

Radiation and SafetyP. Berkvens

1. radiation physics• interaction of electrons with matter• interaction of photons with matter• interaction of neutrons with matter• interaction of protons with matter

2. radiation protection• definitions• rules

3. radiation fields around accelerators• electron accelerators• proton accelerators• synchrotron radiation facilities

4. induced activity

5. radiation monitors


2/95

ionisation potential (eV)

carbon 11.260

oxygen 13.618

potassium 4.341

iron 7.870

lead 7.416

of the order of 10 eV required to ionise an atom

electromagnetic radiation:

directly ionising: charged particles (electrons, protons, …) indirectly ionising: photons, neutrons

nm100hc

E

(hard ultraviolet)

Ionising radiation


3/95





4. induced activity



4/95

The physical processes

1. Ionisation lossesinelastic collisions with orbital electrons

2. Bremsstrahlung lossesinelastic collisions with atomic nuclei

3. Rutherford scattering elastic collisions with atomic nuclei

Positronsat nearly rest energy: annihilationemission of two 511 keV photons

Interaction of electrons with matter


5/95

Electrons – stopping power

)(MeV.cmpower stoppinglinear :dl

dE

)g.(MeV.cmpower stopping mass :dl

dE1

dl

dE1

dl

dE1S

dl

dE1S

1

12

radcoll

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03

energy (MeV)

sto

pp

ing

po

we

r (M

eV

.cm

2.g

-1)

collision

radiative

total

Graphite – Z = 6Graphite – Z = 6Graphite – Z = 6Graphite – Z = 6

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03

energy (MeV)

sto

pp

ing

po

we

r (M

eV

.cm

2.g

-1)

collision

radiative

total

Lead – Z = 82Lead – Z = 82Lead – Z = 82Lead – Z = 82

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03

energy (MeV)

sto

pp

ing

po

we

r (M

eV

.cm

2.g

-1)

collision

radiative

total

Copper – Z = 29Copper – Z = 29Copper – Z = 29Copper – Z = 29


6/95

0

E totCSDA

0

dES

1r

Continuous Slowing Down Approximation range

Radiation yield

Fraction of the initial kinetic energy that is converted to bremsstrahlung energy as the electron slows down to rest.

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03

energy (MeV)

CS

DA

ra

ng

e (

cm

-2.g

)

graphite

copper

lead

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03

energy (MeV)

rad

iati

on

yie

ld

graphite

copper

lead


7/95

Differential bremsstrahlung cross section

k: photon energyT: electron kinetic energy0

5

10

15

20

25

0 0.2 0.4 0.6 0.8 1

k/T

mb

arn

10 MeV

100 MeV

1 GeV

10 GeV

0

2

4

6

8

10

12

0 0.2 0.4 0.6 0.8 1

k/T

mb

arn

10 MeV

100 MeV

1 GeV

10 GeV

dk

dk

Z

2

1

k/T

k/T

mbarn

lead – Z = 82

carbon – Z = 6

mbarn


8/95

Multiple scattering

dx

d1S

X

X

p

E

2

sc

0

2

s2

mean scattering angle

mass scattering power Ssc

Es = 21.2 MeVX0: radiation length: v/cp: momentum

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+00 1.E+01 1.E+02 1.E+03

energy (MeV)

ma

ss

sc

att

eri

ng

po

we

r (r

ad

ian

2.c

m2.g

-1)

graphite

copper

lead


9/95


1. Photo-electric effectremoval of an orbital electron of the inner shells (K,L,M)

2. Compton scatteringinelastic scattering on loosely bound electrons

3. Pair production production of e-/e+ pairessentially with nuclei

4. Rayleigh scatteringelastic scatteringnot important for radiation physics

Interaction of photons with matter


10/95

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05

energy (MeV)

cro

ss

se

cti

on

(c

m2.g

-1)

coherent

com pton

photoelectric

pair production

total

Graphite - Z = 6Graphite - Z = 6

Photon cross sections


11/95

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05

energy (MeV)

cro

ss

se

cti

on

(c

m2.g

-1)

coherent

com pton

photoelectric

pair production

total

Lead - Z = 82Lead - Z = 82

Photon cross sections


12/95

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05

energy (MeV)

cro

ss

se

cti

on

(c

m2.g

-1)

coherent

com pton

photoelectric

pair production

total

K L M N

photo-electron

incoming X-ray

E

E0

E = E – E0

K L M N

E2

E1 E0

E = E0 – E1 = K

E = E0 – E2 = K

The K lines

K L M NE2

E1

E3

E = E1 – E2 = L

E = E1 – E3

= L

The L lines

K L M N

E2

E1

E3

E = E1 – E2 – E3

Auger-electron

Auger electron

Photo-electric effect


13/95

scattered photon

compton electronenergy = E0 - Ec

primary photonenergy E0

cos1cm

E1

EE

20

0

0c

energy Ec

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

0 30 60 90 120 150 180

(degrees)

Ec (

Me

V)

50 keV

100 keV

500 keV

1 MeV

10 MeV

100 MeV

1.E-03

1.E-02

1.E-01

1.E+00

0 30 60 90 120 150 180

(degrees)

d/d

(r e

2 x

cm

2 /

ele

ctr

on

)

50 keV

100 keV

500 keV

1 MeV

10 MeV

100 MeV

d/d (re2 x cm2 / electron)Ec (MeV)

Compton scattering

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05

energy (MeV)

cro

ss

se

cti

on

(c

m2.g

-1)

coherent

com pton

photoelectric

pair production

total


14/95

nucleus Z2

threshold: 1.022 MeV

electron Zthreshold: 2.044 MeV

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.2 0.4 0.6 0.8 1

E/k

rela

tiv

e p

rob

ab

ilit

y

Pair production

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05

energy (MeV)

cro

ss

se

cti

on

(c

m2.g

-1)

coherent

com pton

photoelectric

pair production

total


15/95

Interaction of photons with matterMacroscopic description - Attenuation factors

The mass attenuation coefficient /:

units: cm2.g-1

The linear attenuation coefficient :

units: cm-1

The conversion factor from (barns.atom-1) to / (cm2.g-1):

dl

dN

N

1

dl

dN

N

1

A

N10 A24

0

0 .1

0 .2

0 .3

0 .4

0 .5

0 .6

0 .7

0 .8

0 .9

1

0 1 2 3 4 5 6 7 8 9 1 0

d (cm)d (g.cm-2)

N)(

0

)(0

2

cmgd

cmd

eNN

eNN


16/95

-5

-4

-3

-2

-1

0

1

2

3

4

5

0 5 10 15

cm

cm

photon

electron

positron

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

0 1 2 3 4 5

cm

cm

one 500 MeV electron interacting with lead target

cm

Electromagnetic cascade


17/95

-10

-8

-6

-4

-2

0

2

4

6

8

10

0 5 10 15 20

cm

cm

photon

electron

positron

one 6 GeV electron interacting with lead target

cm

Electromagnetic cascade

-0.1

0

0.1

0.8 1 1.2 1.4 1.6 1.8 2

cm

cm


18/95

0

10

20

30

40

50

60

70

80

10 20 30 40

Energy [MeV]

Cro

ss-s

ectio

n [m

barn

]

Giant resonance

55Mn(γ, n)54Mn

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

10 100 1000

energy (MeV)

cro

ss

-se

cti

on

(c

m-1)

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1 10 100 1000

energy (MeV)

cros

s-se

ctio

n (m

barn

)

Quasi-deuteron

d

AvQD A

N

A

ZZA

γ(d,p)nγ(d,p)n

Photo-pion

ee-60/E-60/E γ(d,p)nγ(d,p)n

Photonuclear reactions

Neutron production

photonuclear reactions


19/95

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

0 5 10 15 20

energy (MeV)n

um

ber

of n

eutr

on

s

Example: neutron spectrum produced by 600 MeV electrons on Cu target

Giant resonance

Quasi-deuteronPhoto-pion

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+00 1.E+01 1.E+02 1.E+03

energy (MeV)

nu

mb

er

of

ne

utr

on

s

Photonuclear reactions

Neutron production


20/95

1. elastic scattering• compound elastic scattering• potential scattering

2. inelastic scattering (n,n’)

3. other inelastic reactions: (n,p), (n,), …

4. absorption reactions• radiative capture• charged particle reactions

5. direct reactions: spallation


Interaction of neutrons with matter


21/95

etc.

Inelasticgamma-ray

ZA + neutron

etc.

ZA+1

Capturegamma-rays

Compoundinelastic scattering

Compoundelastic scattering

Compoundnucleus

formation

EC

B

virtualenergy

Compound nucleus formation

target nucleus ZA

neutronenergy = EC


22/95

Example 1: iron

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

energy (eV)

cro

ss

se

cti

on

(b

arn

)

total

elastic

capture

inelastic

Neutron cross sections

etc.

Inelasticgamma-ray

ZA + neutron

etc.

ZA+1

Capturegamma-rays



Compoundnucleus

formation

EC

B

virtualenergy


23/95

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

en ergy (eV)

cro

ss

se

cti

on

(b

arn

)

total

elastic

captu re

in elastic

Example 2: cadmium


etc.

Inelasticgamma-ray

ZA + neutron

etc.

ZA+1

Capturegamma-rays



Compoundnucleus

formation

EC

B

virtualenergy


24/95

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

energy (eV)

cro

ss

se

cti

on

(b

arn

)

total

elastic

capture

Example 3: hydrogen


etc.

Inelasticgamma-ray

ZA + neutron

etc.

ZA+1

Capturegamma-rays



Compoundnucleus

formation

EC

B

virtualenergy


25/95

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

energy (eV)

cro

ss

se

cti

on

(b

arn

)

total

elastic

capture

inelastic

(n,alpha)

Example 4: boron


etc.

Inelasticgamma-ray

ZA + neutron

etc.

ZA+1

Capturegamma-rays



Compoundnucleus

formation

EC

B

virtualenergy


26/95

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

energy (eV)

cro

ss

se

cti

on

(b

arn

)

total

elastic

capture

inelastic

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03

proton energy (GeV)

no

ne

las

tic

cro

ss

se

cti

on

(b

)

C

Al

Fe

Cu

W

Pb Example: iron


neutron energy (GeV)

inelastic cross section (barn)


27/95

target nucleus

initial neutronenergy = E0

recoiling nucleus

scattered neutronenergy = E1

00

2

imummin,1 EE1A

1AE

0E12

1E

Minimum energy of scattered neutron:

Average energy loss per collision:

target E1,minimum

Hydrogen

(A=1)

0 0.5 E0

Iron(A=56)

0.93 E0 0.034 E0

Lead(A=207)

0.98 E0 0.0096

E0

E

Interaction of neutrons with matter

Elastic scattering


28/95

1. ionisation2. inelastic proton-nucleus scattering

spallation


Interaction of protons with matter


29/95

1.E+00

1.E+01

1.E+02

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05

AlFe

Pb

minimum ionising particle

Proton ionisation loss – Stopping power

stopping power (MeV.g-1.cm2)

proton energy (MeV)


30/95

1,E-05

1,E-04

1,E-03

1,E-02

1,E-01

1,E+00

1,E+01

1,E+02

1,E+03

1,E+04

1,E-03 1,E-02 1,E-01 1,E+00 1,E+01 1,E+02 1,E+03 1,E+04

energy (MeV)

CS

DA

ra

ng

e (

g.c

m-2

)

electron

proton

Comparison CSDA range of protons and electrons in iron


31/95

p

pn

n

n

intra-nuclear cascadeintra-nuclear cascade

n

d

incident proton(GeV range)

evaporationevaporation

Inelastic proton – nucleus scattering

Spallation reaction


32/95

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03

proton energy (GeV)

no

ne

las

tic

cro

ss

se

cti

on

(b

)

C

Al

Fe

Cu

W

Pb

.042.0 7.0 barnAinel E > 1 GeV


Spallation reactionInelastic cross section


33/95

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04

proton energy (MeV)

ine

las

tic

pro

ba

bilt

y (

%)

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

ran

ge

(c

m)

concreteC

Al

FeP

Cu

W

Cconcrete

AlW

PbFe

Cu

Comparison ionisation energy loss and inelastic scattering

E > 1 GeV: 100 % probability for spallation reaction



34/95

inter-nuclear cascades

p

pn

n

n

intra-nuclear cascade

fission products

fast inducedfission

n

d

fission products

n

n

(n,n’), (n,xn),(n,) ,… reactions

spallation product , , decay

fissionfission


Neutron transport below 20 MeV

evaporation

n

n

n

np

Spallation


35/95

Spallation


36/95





4. induced activity



37/95

Biological effects:

Effective dose E-

Ambient dose equivalent H*(d)

Absorbed dose D

dt

dDD

dm

dD

gray (Gy): 1 Gy = 1 J.kg-1

(rad: 1 rad = 0.01 Gy)

2lnT

e)0(N)t(N

)t(Ndt

dN

2/1

t

becquerel (Bq): 1 Bq = 1 s-1

(curie (Ci): 1 Ci = 3.7 1010 Bq)

Activity Fluence F

particles per cm2

1/distance2

Introduction to radiation protection


38/95

Unit of equivalent dose: J.kg-1 Special name: sievert (Sv)Old unit: rem (1 Sv = 100 rem)

Tm

TT Ddm

mD

1Organ dose DT

Individual organ,e.g. stomach

RTRRT DwH ,,

R

RTRT DwH ,

Tissue or organ equivalent dose HT,R

Type and energy range of radiation Radiation weighting factor

wR Photons, all energies 1 Electrons and muons, all energies 1 Neutrons

< 10 keV 10 - 100 keV > 100 keV to 2 MeV >2 - 20 MeV > 20 MeV

10 5 10 20 10 5

Protons, energy > 2 MeV 5 Alpha particles, fission fragments, heavy nuclei

20

International Commission on Radiological Protection (ICRP)Protection quantities - ICRP Publication 60 (1991)


39/95

T

TT HwE

Effective dose E different organs

Tissue or organ Tissue weighting factor wT Gonads 0.20 Bone marrow (red) 0.12 Colon 0.12 Lung 0.12 Stomach 0.12 Bladder 0.05 Breast 0.05 Liver 0.05 Oesophagus 0.05 Thyroid 0.05 Skin 0.01 Bone surface 0.01 Remainder 0.05

Unit of effective dose: Sv

Dose limits on:• Effective dose E• Tissue or organ equivalent dose HT



40/95

Irradiation Irradiation geometriegeometriess

Antero-posterior(AP)

Rotational(ROT)

Isotropic(ISO)

Lateral(LAT)

Postero-anterior(PA)



41/95

Basic principlesBasic principles

• Radiation protection measures must guarantee that deterministic radiation damage is avoided. Since deterministic damage appears above a threshold dose, this dose must not be exceeded.

• The probability of stochastic radiation damage, which has no threshold dose according to the dose-effect relationships currently taken as a basis, must not exceed a justifiable size.ICRP Publication 60ICRP Publication 60

• The necessity of justifying each radiation application by its benefits.

• The demand for optimising radiation protection measures:

ALARA principle: As Low As Reasonably Achievable.

• The establishment of individual limits for radiation exposure of people on the basis of a justifiable risk.



42/95

Application Dose limit Occupational Public

Effective dose 20 mSv per year, averaged over defined periods of 5 years, not

exceeding 50 mSv in any single year

1 mSv in a year

Annual equivalent dose in

The lens of the eye 150 mSv 15 mSv

The skin 500 mSv 50 mSv

The hands and feet 500 mSv - radiation workers 20 mSv .y-1

10 Sv.h-1 *

non-exposed workers 1 mSv .y-1

0.5 Sv .h-1 *

public 1 mSv .y-1

0.11 Sv .h-1 **

* 2000 working hours/year** 8760 hours/year



43/95


ICRP 60 ICRP 103

Gonads 0.20 0.08

Bone marrow (red) 0.12 0.12

Colon 0.12 0.12

Lung 0.12 0.12

Stomach 0.12 0.12

Bladder 0.05 0.04

Breast 0.05 0.12

Liver 0.05 0.04

Oesophagus 0.05 0.04

Thyroid 0.05 0.04

Skin 0.01 0.01

Bone surface 0.01 0.01

Brain - 0.01

Salivary gland - 0.01

Remainder 0.05 0.12

Total 1 1

Tissue weighting factor wT

MeV50E,e25.35.2

MeV50EMeV1,e0.170.5

MeV1E,e2.185.2

n6/E04.0ln

n6/E2ln

n6/Eln

2n

2n

2n

ICRP Publication 103-

Radiation weighting factor wR

neutrons

protons: 2


44/95

International Commission on Radiation Units and Measurements ICRU Report 51 (1993)

Protection quantities (ICRP) operational quantities

DQH

Dose equivalent

Unit of dose equivalent: Sv Unrestricted linear energy

transfer

L (keVµm-1)

Quality factor

Q

L < 10 1

10 L 100 0.32 L - 2.2

L > 100 300 / L1/2

d point ofmeasurement

expanded and aligned field

ICRU sphere 30 cm diameter tissue-equivalent sphere:

density 1 g.cm-3

composition by mass: 76.2 % O, 11.1 % C, 10.1 % H and 2.6 % N

Ambient dose equivalent H*(d)

H*(10) (d = 10 mm)


45/95

0.001

0.01

0.1

1

10

1.E-02 1.E-01 1.E+00 1.E+01

Photon energy (MeV)

Sv/G

y

E(AP)K

E(ROT)/K

H*(10)/K

Ratio of effective dose E to air kerma free-in-air (AP and ROT) and ratio of ambient dose equivalent H*(10) to air kerma free-to-air as a function of photon energy.

0.01

0.1

1

1.E-02 1.E-01 1.E+00 1.E+01

Photon energy (MeV)

Sv/

Gy

E(AP)/H*(10)

E(ROT)/H*(10)Ratio of effective dose E (AP

and ROT) to ambient dose equivalent H*(10) as a function

of photon energy.

Comparison between protection quantities (ICRP) and operational quantities (ICRU) – ICRU Report 57 (1998)


46/95

Effective dose E per unit neutron fluence (AP and ROT) and ambient dose equivalent H*(10) per unit neutron fluence as a function of neutron energy.

1

10

100

1000

1.E-09 1.E-07 1.E-05 1.E-03 1.E-01 1.E+01 1.E+03

neutron energy (MeV)

pSv.

cm-2

E(AP)/F

E(ROT)/F

H*(10)/F

0

1

2

1.E-09 1.E-07 1.E-05 1.E-03 1.E-01 1.E+01 1.E+03

neutron energy (MeV)

pSv.

cm-2

E(ROT)/H*(10)

E(AP)/H*(10)

Ratio of effective dose E (AP and ROT) to ambient dose equivalent

H*(10) as a function of neutron energy.

Comparison between protection quantities (ICRP) and operational quantities (ICRU) – ICRU Report 57 (1998)


47/95





4. induced activity



48/95

electron accelerators

photons (bremsstrahlung)neutrons

proton accelerators

neutrons

synchrotron radiation facilities

acceleratorsbeamlines

Prompt radiation fields around accelerators


49/95

Examples of neutron spectra

Example 1: calculated neutron spectra for the 1.7 GeV BESSY storage ring (Courtesy of Klaus Ott)

Radiation fields around electron accelerators


50/95

0.0E+00

5.0E+01

1.0E+02

1.5E+02

2.0E+02

E E

1.0E+00 1.0E+01

Neutron Energy (MeV)


Example 2: measured neutron spectrum on the roof of the 6 GeV ESRF storage ring (behind 1.2 m concrete shielding)

Radiation fields around electron accelerators


51/95

Type of radiation

Energy range

Estimated % of neutron

flux density

Estimated % of total

dose equivalent

Neutrons < 1 eV < 7 <1

Neutrons 1 eV – 0.7 MeV 70 20

Neutrons 0.7 – 3 MeV 15 35

Neutrons 3 – 7 MeV 7 25

Neutrons 7 – 20 MeV 1.5 5

Neutrons + protons 20 – 100 MeV 1 5

Neutrons + charged particles > 100 MeV 0.5 4

Other particles + gammas - - < 2

7 GeV proton synchrotron NIMROD

Radiation fields around proton accelerators


52/95

Source: Compendium of Neutron Spectra and Detector Responses for Radiation Protection Purposes – Technical Reports Series no. 403 , IAEA, 2001


1 MeV



53/95



1 MeV



54/95



1 MeV



55/95

i

2

d

H

r

WeFH

i

i

targettarget

incident beamincident beam

dd

rr

H

H : dose equivalent rate, in Sv×h-1 W: primary beam loss rate, in kW

iHF : fluence to (unshielded) dose equivalent conversion factor, in Sv×h-1 (kW×m-2)-1

d: shield wall thickness, in g×cm-2

i: attenuation length for the ith radiation component, in g×cm-2

r: distance from the source to the dose point, in m i: sum over different radiation components

Accelerator shielding

Analytical models


56/95

iHF : fluence to (unshielded) dose equivalent conversion factor

secondary radiation

Sv.h-1.kW-1 at 1 m

at 0 degat 90 deg

bremsstrahlung 300× E(MeV) 50

neutrons < 25 MeV 20 20

neutrons 25 – 100 MeV

- 2.4

neutrons > 100 MeV 9.2 0.72

radiationconcret

e

cmiron lead

bremsstrahlung 21 4.7 2.4

neutrons < 25 MeV 18 16 -

neutrons 25 – 100 MeV

28 - -

neutrons > 100 MeV 43 18 17

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1 10 100 1000

electron energy (MeV)

Sv.h

-1 (k

W.m

-2)-1

forewarddirection

sidewarddirection (90 degrees)

bremsstrahlung

i:attenuation length

Accelerator shielding: electron accelerator

Analytical models

fluence to (unshielded) dose equivalent conversion factor


57/95

Accelerator shielding

Monte-Carlo codesExamples: MCNPX

PENELOPEFLUKAMARS

<0.2 mrem/h

[mSv/h]

[mrem/h]

[mSv/h]

[mrem/h]

[mSv/h]

[mrem/h]Aspect ratio

1:2

Beam dump hall FEE NEH

<0.0025 mrem/h<0.025 mrem/h1rem/h

5kW @

beam

dump

5W @

BYD1

Example: MARS calculation for the electron dump line of the LCLS facility - Courtesy of T. Sanami.


58/95

Synchrotron radiation facilities

15 m

ID vessel

optics hutch

front end

concrete wallneutrons

photons

Radiation fieldsAccelerator tunnels:

photons, neutronsBeamlines:

X-rays, photons, neutrons


59/95

Example: ESRF 6 GeV storage ring, continuous beam loss during injection:10 mA, 1 s, 1 Hz, 6 GeV

0.5 mSv/h

1.6 mSv/h

1.2 m ordinary concrete

1 m heavy concrete


Storage ring shielding


60/95

lead

heavy concrete

lead

heavy concrete0.5 Sv/h

0.5 Sv/hExample: ESRF 6 GeV storage ring, continuous beam loss during injection:10 mA, 1 s, 1 Hz, 6 GeV


Storage ring shielding


61/95

3 mm Fe

1 mm Fe

1 mm Feplomb

120 cm

0.1

1

10

100

1000

10000

0 5 10 15 20 25 30

mm Pb

Sv.

h-1

6 mrad bend

3 U35

W150

in-vacuum

0,5 Sv.h-1


Beamline shielding: synchrotron radiation

120 cm

lead


62/95

0

0.1

0.2

0.3

0.4

0.5

20 30 40 50 60 70 80 90

Sv.

h-1

6 mrad bend

3 U35

W150

in-vacuum

angle (degrés)

3 mm Fe

1 mm Fe

1 mm Feplomb

120 cm



120 cm

lead


63/95

3 mm Fe

1 mm Fe

1 mm Feplomb

120 cm



120 cm

lead

1.E-07

1.E-04

1.E-01

1.E+02

1.E+05

1.E+08

1.E+11

1.E+14

1.E+17

1 10 100 1000

energie (keV)

ph/s

/0.0

01E 0 mm

1 mm

5 mm

8 mm


64/95


Beamline shielding: gas-bremsstrahlung

,LIpEdx

dECP e

LIEP e 22

Gas-bremsstrahlung power: electron stopping powerpressure in straight sectionelectron beam intensitylength of straight section

IEp

EEdx

dE

e

ee

The shielding requirements for the optics hutches of 3rd generation insertion device beamlines are largely determined by gas-bremsstrahlung (and photo-neutrons).

ESRF SRS Diamond Soleil

Energy (GeV) 6 2 3 2.75

Current (mA) 200 250 500 500

Straight section (m) 15 3.82 15.75 18.75 7.7 12.4 18.5

Bremsstrahlung power

(normalised to ESRF)

1 0.044 1.64 1.95 0.67 1.09 1.62

IEp

EEdx

dE

e

ee


65/95



fentes primaires en Cu miroir en Si

écran en Pb, épaisseur 2 cm, 20 x 20 cm2

monochromateur avec arrêtoir en W,épaisseur 10 cm, 6 cm

120 cm

50 cm 100 cm 150 cm 200 cm

1000 cm

primary slits (Cu)mirror (Si)

Pb screen, 2 cm, 20 x 20 cm2

monochromator + W beamstop 10 cm, 6 cm

fentes primaires en Cu miroir en Si

écran en Pb, épaisseur 2 cm, 20 x 20 cm2

monochromateur avec arrêtoir en W,épaisseur 10 cm, 6 cm

120 cm

50 cm 100 cm 150 cm 200 cm

1000 cm

distance le long de l’axe du faisceau (cm)

début de la cabine

débit de dose (Sv.h-1)

1.E-02

1.E-01

1.E+00

-200 0 200 400 600 800 1000

effective dose rate (Sv.h-1)

distance along hutch (cm)

distance le long de l’axe du faisceau (cm)

début de la cabine

débit de dose (Sv.h-1)

1.E-02

1.E-01

1.E+00

-200 0 200 400 600 800 1000

photons

neutrons

Example: typical ESRF Optics Hutch - Sidewall: 3 cm Pb6 GeV, 200 mA, average pressure straight section 5 × 10-9 mbar


66/95

1.E-07

1.E-06

1.E-05

1.E-04

0.01 0.1 1 10 100On-axis bremsstrahlung measurements during initial conditioning of ESRF 5 m long, 8 mm internal height NEG-coated extruded aluminium ID vessels

factor 2.5

2 orders of magnitude

electron dose (Ah)

Gy/h/mA2

23 days continuous operation at 185 mA




67/95

0100200300

0 10 20 30 40 50

stored beam current (mA)

time (days)

1.E-10

1.E-09

1.E-08

1.E-07

0 10 20 30 40 50

1 × 10-7

1 × 10-8

1 × 10-9

1 × 10-10

penning gauge no. 1 (mbar)



Example: ID12 beamline at ESRF


68/95

0.0E+00

5.0E+04

1.0E+05

1.5E+05

2.0E+05

2.5E+05

0 10 20 30 40 50

0100200300

0 10 20 30 40 50

stored beam current during user operation (mA)

time (days)

2 × 105

1.5 × 105

5 × 104

1 × 105

2.5 × 105

0

∫I×ppenning 1.dt (mA×10-9 mbar × h)





69/95

0.0E+00

5.0E+04

1.0E+05

1.5E+05

2.0E+05

2.5E+05

0 10 20 30 40 50

0

10

20

30

40

50

0100200300

0 10 20 30 40 50

stored beam current during user operation (mA)

time (days)

∫I×ppenning 1.dt (mA×10-9 mbar × h) ambient dose equivalent (Sv)

(× 0.55)

photons

neutrons

2 × 105

1.5 × 105

5 × 104

1 × 105

2.5 × 105

0





70/95

distance along beam axis (cm)

ambient dose equivalent rate (Sv/h)

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0 500 1000 1500

photons

neutrons

total

Series4

Series5

Series6

Series7

calculatedphotonsneutronstotal

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0 500 1000 1500

photons

neutrons

total

Series4

Series5

Series6

Series7

measuredphotonsneutronstotal

average pressure in straight section: 1 × 10-9 mbarstored beam current: 200 mA

0.00

0.02

0.04

0.06

0.08

0.10

0 200 400 600 800 1000

0.5 Sv/h:300 mA, 3.8 × 10-9 mbar





71/95





4. induced activity



72/95

• thermal and slow neutron reactions• medium energy neutron reactions• nuclear reactions at high energy (spallation)• photonuclear reactions

• radiation remains after accelerator switched off• work permits for people entering tunnels• radiation protection: personnel and environment• management of activated accelerator components• decommissioning of facilities

relatively insensitive to activation

moderately susceptible to activation

highly susceptible to activation

fissionable

ordinary concrete, Pb, Al, wood, plastics

Fe (steel, ferrites), Cu Stainless steel, W, Ta, Zn, Au, Mn, Co, Ni

U, Pu, Th

Induced activity


73/95

Number of neutrons

Number of protons

Induced activity


74/95

0

10

20

30

40

50

60

70

80

10 15 20 25 30 35 40

energy [MeV]

cro

ss

se

cti

on

[m

ba

rn]

55Mn(, n)54Mn photonuclear reactions(,n), (,p), (,np), …

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

10 100 1000

energy [MeV]

cro

ss s

ecti

on

[1/

cm]

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

10 100 1000

energy [MeV]

cro

ss s

ecti

on

[1/

cm]

Activation from electron beam


75/95


inelastic reactions (n,p), (n,), …

0.00

0.01

0.01

0.02

0.02

0.03

0.03

0.04

0.04

0 5 10 15 20

energy (MeV)

cro

ss s

ect

ion

(b

arn

)

63Cu(n,)60Co0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0 5 10 15 20

energy (MeV)

cro

ss s

ect

ion

(b

arn

)

60Ni(n,p)60Co


76/95

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

energy (eV)

cro

ss

se

cti

on

(b

arn

)


radiative capture

151Eu(n,)152Eu


77/95

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

0.001 0.01 0.1 1 10

cooling time (y)

spec

ific

activ

ity (

Bq.

g-1)

51Cr

54Mn

52Mn

56Mn

60Co

48V

46Sc

44mSc

59Fe

57Co

58Co

48Sc43K

48Cr

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

0.001 0.01 0.1 1 10

cooling time (y)

spec

ific

activ

ity (

Bq.

g-1)

51Cr

54Mn

52Mn

56Mn

60Co

48V

46Sc

44mSc

59Fe

57Co

58Co

48Sc43K

48Cr

Example: cooling down curve of irradiated steel



78/95

Stainless steel vessel ESRF

1

10

100

1000

10000

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900

Energy (ke V)

Co

un

ts

57Co 51

Cr +,-58

Co54

Mn

46Sc

52Mn

56Co

48V



79/95

inter-nuclear cascades

p

pn

n

n

intra-nuclear cascade

fission products

fast inducedfission

n

d

fission products

n

n

(n,n’), (n,xn),(n,) ,… reactions

spallation product , , decay

fissionfission


Neutron transport below 20 MeV

evaporation

n

n

n

np

Activation from proton beam


80/95

Isotope Half-life Decay

mode fSv.h-1.Bq-1 at 1

m 7Be 53 d EC 7.8 11C 20 min + 140 18F 1.8 h + 132

22Na 2.6 y + 298 24Na 15 h + 560 46Sc 84 d + 283 48Sc 1.8 d + 455 48V 16 d + 397 51Cr 28 d EC 4.3 52Mn 5.7 d + 326 54Mn 303 d EC 114 56Co 77 d + 350 60Co 5.3 y + 340 65Zn 245 d EC 76

Principal radioactive isotopes produced in accelerator structures by spallation reactions



81/95

Parent isotope

Natural (%)

(barn)

Active isotope

Half-life

fSv.h-1 at 1m per Bq per g

23Na 100 0.53 24Na 15 h 560 7.7 40Ar 99.6 0.61 41Ar 1.8 h 150 1.4 44Ca 2.0 0.70 45Ca 165 h - - 50Cr 4.3 17 51Cr 28 d 4 0.04 55Mn 100 13 56Mn 2.6 h 2520 35 59Co 100 37 60Co 5.3 y 340 128 63Cu 69 4.5 64Cu 13 h 28 0.84 64Zn 49 0.46 65Zn 245 d 76 0.16 121Sb 57 6.1 122Sb 2.8 d 60 1.0 123Sb 43 3.3 124Sb 60 d 200 1.4 133Cs 100 31 134Cs 2.1 y 116 17 151Eu 48 8700 152Eu 12 y 45 750 153Eu 52 320 154Eu 8 y 286 190 186W 28 40 187W 1d 73 2.6

Most important isotopes near high energy particle accelerators formed by thermal neutron capture



82/95





4. induced activity



83/95

0

50

100

150

200

250

0 1 0 2 0 3 0 4 0 5 0

mA

0.1

1.0

10.0

0 10 20 30 40 50

days since 18/01/02

do

se

ra

te (

S

v.h-1

)

Example: photon dose rate measurement around ESRF storage ring

Radiation monitoring


84/95

I

w H2 He O2 Ar Air

electrons 36.3 eV 41 eV 31 eV 26.4 eV 34 eV

alphas 36.5 eV 44 eV 32.4 eV 26.4 eV 35.3 eV

VI

V

ionisation chamber

proportional counter

Geiger-Müller counter

IVe

w

dt

dD

dt

dN

V

w

dt

dD

w

EN

gasgas

pairs

gasgas

pairs

EE


Gas-filled detectors


85/95


Ionisation chambers


86/95


Proportional counter


87/95


Geiger - Müller counter


88/95


Neutron monitors

Example: neutron spectrum around the 1.7 GeV BESSY storage ring (Courtesy of Klaus Ott)


89/95

%)6(MeV792.2Li

%)94(MeV310.2LiBn

keV765HpHen

73

7310

5

33

3He-filled proportional counter:

BF3 counter:

Polyethylene moderator

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

energy (eV)

cros

s se

ctio

n (b

arn)

3He(n,p)3H33He(n,p)He(n,p)33HH

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

energy (eV)

cros

s se

ctio

n (b

arn)

3He(n,p)3H33He(n,p)He(n,p)33HH

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

energy (eV)

cros

s se

ctio

n (b

arn)

10B(n,)7Li1010B(n,B(n,))77LiLi

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

energy (eV)

cros

s se

ctio

n (b

arn)

10B(n,)7Li1010B(n,B(n,))77LiLi


Moderated neutron monitors


90/95

0

0 .2

0 .4

0 .6

0 .8

1

1 .2

1 .E-4 1 .E-3 1 .E-2 1 .E-1 1 .E+0 1 .E+1 1 .E+2

e n e rg y (Me V)

µS

v .

cm

2 (

rela

tiv

e u

nit

s)

ICRP

CRAMAL-31




91/95



Neutron response enhancement using lead-shell in moderator type counters

BertholdLB-6411


92/95

expanded bubble(~ 0.1 – 0.6 mm)

superheated drop(20 – 100 m)

neutron

chargedparticle

vapour embryo< 0.1 m


Superheated emulsions

0

8

0 3

temperature

pre

ssu

re

solid

liquid

vapour

superheating

over-expansion


93/95

Thermal neutrons: OK

Epithermal neutrons: not important

0.1 – 10 MeV: OK

Under-read > 10 MeV

Energy response of SDD100 vials (dichlorodifluoromethane)




94/95



effect of lead moderator


95/95

Acoustic bubble counting

Model ABC1260Framework Scientificwww.framesci.com



juas 2010 – p. berkvens, radiation & safety 1/95 radiation and safety p. berkvens 1.radiation...

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