Transcript Radioactive Decay

Radioactive decay

is the process by which an unstable atomic
nucleus loses energy by emitting ionizing
particles or radiation. The emission is
spontaneous in that the nucleus decnt nuclide,
transforming to an atom of ays without collision
with another particle. This decay, or loss of
energy, results in an atom of one type, called
the parea different type, named the daughter
nuclide, 14C ------- 15N
RADIOACTIVE DECAY
• Atom (nuclei) yang mempunyai rasio
proton – neutron berada di luar Belt of
stability secara langsung akan mengalami
radioactive decay secara Spontan
• Tipe Decay tergantung dimana posisi
atom berada relative terhadap band of stability
• Radioactive particle are emitted with
different kinetic energy
- Energy change is related to the change
in binding energy from reactant to product
BAND STABILITY AND RADIOACTIVE DECAY
Mode of decay
Participating particles
Daughter nucleus
An alpha particle (A = 4, Z = 2) emitted
from nucleus
A proton ejected from nucleus
A neutron ejected from nucleus
Two protons ejected from nucleus
simultaneously
Nucleus disintegrates into two or more
smaller nuclei and other particles
Nucleus emits a specific type of smaller
nucleus (A1, Z1) smaller than, or larger
than, an alpha particle
(A − 4, Z − 2)
Decays with emission of nucleons:
Alpha decay
Proton emission
Neutron emission
Double proton emission
Spontaneous fission
Cluster decay
(A − 1, Z − 1)
(A − 1, Z)
(A − 2, Z − 2)
—
(A − A1, Z − Z1) + (A1, Z1)
Different modes of beta decay:
A nucleus emits an electron and an
electron antineutrino
A nucleus emits a positron and a electron
Positron emission (β+ decay)
neutrino
A nucleus captures an orbiting electron
and emits a neutrino – the daughter
Electron capture
nucleus is left in an excited and unstable
state
A nucleus emits two electrons and two
Double beta decay
antineutrinos
A nucleus absorbs two orbital electrons
and emits two neutrinos – the daughter
Double electron capture
nucleus is left in an excited and unstable
state
A nucleus absorbs one orbital electron,
Electron capture with positron emission
emits one positron and two neutrinos
A nucleus emits two positrons and two
Double positron emission
neutrinos
Transitions between states of the same nucleus:
Excited nucleus releases a high-energy
Isomeric transition
photon (gamma ray)
Excited nucleus transfers energy to an
Internal conversion
orbital electron and it is ejected from the
atom
β− decay
(A, Z + 1)
(A, Z − 1)
(A, Z − 1)
(A, Z + 2)
(A, Z − 2)
(A, Z − 2)
(A, Z − 2)
(A, Z)
(A
CONTOH NATURAL DECAY
An example is the natural decay chain of 238U which is as follows:
decays, through alpha-emission, with a half-life of 4.5 billion years to thorium-234
which decays, through beta-emission, with a half-life of 24 days to protactinium-234
which decays, through beta-emission, with a half-life of 1.2 minutes to uranium-234
which decays, through alpha-emission, with a half-life of 240 thousand years to
thorium-230
which decays, through alpha-emission, with a half-life of 77 thousand years to radium226
which decays, through alpha-emission, with a half-life of 1.6 thousand years to radon222
which decays, through alpha-emission, with a half-life of 3.8 days to polonium-218
which decays, through alpha-emission, with a half-life of 3.1 minutes to lead-214
which decays, through beta-emission, with a half-life of 27 minutes to bismuth-214
which decays, through beta-emission, with a half-life of 20 minutes to polonium-214
which decays, through alpha-emission, with a half-life of 160 microseconds to lead-210
which decays, through beta-emission, with a half-life of 22 years to bismuth-210
which decays, through beta-emission, with a half-life of 5 days to polonium-210
which decays, through alpha-emission, with a half-life of 140 days to lead-206, which is
a stable nuclide.
Nuclear Stability and Radioactive Decay
Beta decay
14C
6
40K
19
+ 0b + n
14N
7
Decrease # of neutrons by 1
-1
40Ca
+ 0b + n
Increase # of protons by 1
-1
20
1n
0
1p
+ 0b + n
1
-1
Positron decay
11C
11B
+ 0b + n
Increase # of neutrons by 1
38K
38Ar
+ 0b + n
Decrease # of protons by 1
6
19
5
18
+1
+1
1p
1
n and
1n
+ 0b + n
0
+1
n have A = 0 and Z = 0
Nuclear Stability and Radioactive Decay
Electron capture decay
37Ar
+ 0e
55Fe
+
18
26
37Cl
+ n
Increase # of neutrons by 1
17
-1
0e
55Mn
25
-1
+ n
Decrease # of protons by 1
1
Alpha decay
1p
+ 0e
-1
1n
+n
0
Decrease # of neutrons by 2
212Po
84
4He
2
+
208Pb
82
Decrease # of protons by 2
Spontaneous fission
252Cf
98
HITUNG PERUBAHAN ENERGI BINDING
PADA PROSES DECAY DIATAS ?
2125In + 21n
49
0
23.2
HALF-LIFE
•
•
HALF-LIFE is the time that it takes for
1/2 a sample to decompose.
The rate of a nuclear transformation
depends only on the “reactant”
concentration.
HALF-LIFE
Decay of 20.0 mg of 15O. What remains after 3 half-lives? After 5 half-lives?
263Sg
----> 259Rf + 4He
Terjadi pada Solar Energi dan Proses terjadinya alam semesta
Terjadi pada proses bom nuklir dan reaktor nuklir kini
KINETICS OF RADIOACTIVE
DECAY
For each duration (half-life), one half of the substance
decomposes.
For example: Ra-234 has a half-life of 3.6 days
If you start with 50 grams of Ra-234
After 3.6 days > 25 grams
After 7.2 days > 12.5 grams
After 10.8 days > 6.25 grams
The probability of decay (−dN/N) is proportional to dt:
The solution to this first-order differential
equation is the following function:
Dimana,
The half life is related to the decay constant as follows:
Kinetics of Radioactive Decay
N
daughter
DN
rate = -
rate = lN
Dt
-
DN
Dt
= lN
lnN = lnN0 - lt
N = N0e(-lt)
N = the number of atoms at time t
N0 = the number of atoms at time t = 0
l is the decay constant (sometimes called k)
l
=
Ln 2
t½
k=
23.3
ACTIVITY CALCULATION
N = N0e(-lt)
UNTUK HALF LIFE
2,303 Log 0,5/1 = -λ t½
λ = 0,693/t½
A = A0e(-l t )
ECERCISE : Hitung sisa aktifitas Tritium setela tersimpan 26 tahun
dari aktifitas semula 15 Ci, t1/2 tritium = 12,34 th
A sample of C14, whose half life is 5730 years, has a decay rate of 14 disintegration per
minute (dpm) per gram of natural C. An artifact is found to have radioactivity of 4 dpm
per gram of its present C, how old is the artifact?
Using the above equation, we have:
Where:
years
years
Kinetics of Radioactive Decay
ln[N] = ln[N]0 - lt
ln [N]
[N]
[N] = [N]0exp(-lt)
23.3
QUANTITATIVE ASPECT OF RADIACTIVE
DECAY
•
•
•
238U
Arithmetically, melalui term half life kemudian dapat dihitung perubahan
jumlah/aktivitas zat radioaktive selama waktu tertentu
Graphycally, Mengunakan grafik semilog antara Aktivita radioaktiv Vs waktu
Radioactive Equilibrium
- Ratio Nomor atom pada proses reaksi decay zat radioaktive seperti dibawah ini,
238U
234Th
234Pa
λu
λTh
NTh / NU = λ U / λ Th
N Th / N U = t½
Th
/ t½ U
- Hal yang sama untuk atome decay dengan nomor atom yang kostan , Ratio Massa
ebanding dengan ratio half life nya,
Massa X / Massa Y
=
t½ X . A X / t½ Y . A Y
Dari perhitungan ratio nomor atom dan massa ada decay reaction maka dapat
dihitung ratio dari ratio nomor atom dan mass dari hasil decay tersebut
Nuclear Reaction
Balancing Nuclear Equations
1. Conserve mass number (A).
The sum of protons plus neutrons in the products must equal the sum of protons plus
neutrons in the reactants.
235 U + 1n
92
0
138 Cs
55
+
96 Rb
37
+2
1n
0
235 + 1 = 138 + 96 + 2x1
2. Conserve atomic number (Z) or nuclear charge.
The sum of nuclear charges in the products must equal the sum of nuclear charges in the
reactants.
235 U + 1n
92
0
138 Cs
55
92 + 0 = 55 + 37 + 2x0
+
96 Rb
37
+2
1n
0
23.1
NUCLEAR REACTIONS
•
Alpha emission
Note that mass number (A) goes down by 4
and atomic number (Z) goes down by 2.
Nucleons (nuclear particles… protons and
neutrons) are rearranged but conserved
NUCLEAR REACTIONS
•
Beta emission
Note that mass number (A) is unchanged and
atomic number (Z) goes up by 1.
OTHER TYPES OF NUCLEAR
REACTIONS
Positron (0+1b): a positive electron
207
Electron capture: the capture of an electron
207
ARTIFICIAL NUCLEAR REACTIONS
New elements or new isotopes of known elements
are produced by bombarding an atom with a
subatomic particle such as a proton or neutron - or even a much heavier particle such as 4He
and 11B.
Reactions using neutrons are called
g reactions because a g ray is usually
emitted.
Radioisotopes used in medicine are often made
by g reactions.
NUCLEAR BOMBARDMENT REACTIONS
Cyclotron or accelerator
Nuclear reactor
ARTIFICIAL TRANSMUTATION TROUGH
ACCELERATOR
CROSS SECTION
Is the probability that a bombarding particle
(neutron) will produce a nuclear reaction
 Cross section Unit is Barn (1 barn = 1024 cm-2)
 Formula ;

N = Φ x σ x nX
 Where, N = Total number of reaction

Φ = Flux neutron

σ = nuclear cross section

n = number of nuclei in Cm3

X = is thickness of target in Cm

NUCLEAR CROSS SECTION
ARTIFICIAL NUCLEAR REACTIONS
Example of a g
reaction is production of
radioactive 31P for use in studies of P
uptake in the body.
31 P
15
+
1 n
0
--->
32 P
15
+ g
TRANSURANIUM ELEMENTS
Elements beyond 92 (transuranium) made
starting with an g reaction
238
92U +
239
92U
239
93Np
1 n
0
--->
239
92U
+ g
--->
239
0 b
Np
+
93
-1
--->
239
94Pu +
0
-1b
NUCLEAR FISSION
NUCLEAR FISSION
Fission is the splitting of atoms
These are usually very large, so that they are not as stable
Fission chain has three general steps:
1. Initiation. Reaction of a single atom starts the
chain (e.g., 235U + neutron)
2. Propagation.
236U
fission releases neutrons that
initiate other fissions
3. ___________ .
EXCERCISE , REACTION FISSION RANTAI URANIUM
Nuclear Fission
235U
92
+ 1n
0
90Sr
+ 143Xe + 31n + Energy
38
54
0
Energy = [mass 235U + mass n – (mass 90Sr + mass 143Xe + 3 x mass n )] x c2
Energy = 3.3 x 10-11J per 235U
= 2.0 x 1013 J per mole 235U
Combustion of 1 ton of coal = 5 x 107 J
23.5
REPRESENTATION OF A FISSION PROCESS.
Nuclear Fission
Nuclear chain reaction is a self-sustaining sequence of nuclear fission reactions.
The minimum mass of fissionable material required to generate a self-sustaining
nuclear chain reaction is the critical mass.
Non-critical
Critical
23.5
DIAGRAM OF A NUCLEAR POWER PLANT
a neutron moderator is a medium that reduces the speed
of fast neutrons, thereby turning them into thermal neutrons
capable of sustaining a nuclear chain reaction involving
uranium-235.
A control rod is a rod made of chemical elements capable of absorbing many
neutrons without fissioning themselves. They are used in nuclear reactors to control
the rate of fission of uranium and plutonium. Because these elements have different
capture cross sections for neutrons of varying energies, the compositions of the
control rods must be designed for the neutron spectrum of the reactor it is supposed
to control. Light water reactors (BWR, PWR) and heavy water reactors (HWR)
operate with "thermal" neutrons, whereas breeder reactors operate with "fast"
neutrons.
A coolant is a fluid which flows through a device to prevent its overheating,
transferring the heat produced by the device to other devices that use or dissipate
it. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic,
and chemically inert, neither causing nor promoting corrosion of the cooling
system. Some applications also require the coolant to be an electrical insulator.
Silver-indium-cadmium alloys, generally 80% Ag, 15% In, and 5% Cd, are a
common control rod material for pressurized water reactors. The somewhat
different energy absorption regions of the materials make the alloy an excellent
neutron absorber. It has good mechanical strength and can be easily fabricated. It
has to be encased in stainless steel to prevent corrosion in hot water.
NUCLEAR FISSION & POWER

Currently about 103
nuclear power plants in
the U.S. and about 435
worldwide.

17% of the world’s
energy comes from
nuclear.
NUCLEAR FUSION
Fusion
small nuclei combine
2H
1
+
3H
1
4He
2
+ 1n +
0
Occurs in the sun and other stars
Energy
Nuclear Fusion
Fusion Reaction
1
2H
1
+ 2H
1
2H
+ 3H
4He
6Li
+ 2H
2 4He
1
3
1
1
Energy Released
3H
+ 1n
2
+ 1H
1
6.3 x 10-13 J
2.8 x 10-12 J
0
3.6 x 10-12 J
2
Tokamak magnetic
plasma confinement
23.6
NUCLEAR FUSION
Fusion
 Excessive heat can not be contained
 Attempts at “cold” fusion have
FAILED.
 “Hot” fusion is difficult to contain
RADIATION CHEMISTRY
Mempelajari efek kimia yang di timbulkan oleh radiasi pengion bila
ia diserap oleh materi
RADIASI : Emisi dan propagasi energi dalam udara dan suatu materi
RADIASI PENGION : Dapat mengionkan dan mengeksitasi target
(Partikel bermuatan/ion /elektron, Gel elektromagnetik/gamma and sinar x,
neutron)
IONISASI : Pelepasan elektron dari orbital suatu atom/molekul netral
- elektron yang terikan paling lemah
- terbentuk ion positif dan elektron bebas
- hanya bisa ditimbulkan oleh radiasi pengion
EKSITASI : Perpindahan elektron ke orbital lebih tinggi dalam suatu
atom/molekul netral menjadi atom/molekul mempunyai energi berlebih
- kembali ke tingkat semula dengan disertai emisi cahaya atau
- terjadi pemutusan ikatan yang lemah menghasilkan radikal bebas
IRADIASI : Paparan terhadap radiasi pengion (berdaya tembus)
Spektrum elektromagnetik
Radiasi pengion
Radiasi non-pengion
Matahari
Matahari/p
Pemancar
/lampu
emanas
UV
Matahari/bola
Tabung
pijar
Pemancar/microwave oven
sinar X
Matahari/
radio
isotop
SUMBER RADIASI



RADIOISOTOPE ALAM DAN BUATAN--------- FOTON DAN PARTIKEL
MESIN PEMERCEPAT (ACCELERATOR) PATIKEL----- BERKAS
ELEKTRON, BERKAS ION
REAKTOR NUKLIR --------- BERKAS NETRON
KARAKTERISASI RADIASI PENGION : DAYA TEMBUS DAN LET
Radiation pengion mempunyai daya tembus, tergantung pada
jenis radiasi, energi foton/partikel dan kerapatan target
LET = Linier Energy Transer defined as the linier (distance)
rate at which energy is lost by radiation traversing a material
medium in unit kev/µ
Radiasi Sinar Gamma terhadap Materi
DNA Sel Mikroba Patogen
terkena radiasi menjadi tidak mampu
berreplikasi dan mati
Daya tembus
Sinar gamma > sinar x > partikel beta > partikel alpha
Partikel alpha > partikel beta > sinar x > sinar gamma
LET
Linear energy transfer (LET) is a measure of the
energy transferred to material as an ionizing
particle travels through it. Typically, this
measure is used to quantify the effects of
ionizing radiation on biological specimens or
electronic devices.
 Linear energy transfer is closely related to
stopping power. Whereas stopping power, the
energy loss per unit distance, dE / dx

PROPERTIES OF NUCLEAR RADIATIONS
ENERGY RANGE
TYPE OF RADIATIONS
LET VALUE IN WATER
(kev/µ)
4 MeV – 9 MeV
Alpha 5 MeV
140
0,5 MeV – 2 MeV
Beta 2 MeV
0,2
0,1 MeV - 2 MeV
Gamma 1,25 MeV
0,3
-
X- Rays
200 KeV
3
INTERACTION PARTICLE WITH MATTER


PARTIKEL ALPHA
- Daya tembus di udara antara 2,5 – 9 cm sedangkan untuk aluminium
antara 0,02 mm – 0,006mm
- Electrostatic interaction dgn orbital electron menghasilkan ionisasi dan
ion pair (ion positive dan ejected electron)
PARTIKEL BETA
- Daya tembus 500 kali partikel alpha pada energi yang sama
- Production of ion pair
- Interaction of fast moving of beta particle produced electromagnetic
radiation (X-ray and gamma ray) near positive field of nucleus disertai
efect bremsstrahlung (slowing down radiation)
Partikel pengion
IONISASI
EKSITASI
e-
ionisasi
α
e-
elektron
ee-
e-
e-
e-
e-
Partikel
pengeksitasi
e-
REAKSI INTI
9
4Be
+
4
2He
------------
13
6C
+
1
1H
INTERAKSI PARTIKEL BETA
-Ionisasi
-Eksitasi
-Bremstrahlung
e-
Sinar x
ß
eee-
eeElektron dg energi
Berkurang /Bremsstraslung

Gamma Rays
-Photoelectric absorption, gamma photon expends all of its
energy to eject an orbital electron from inner shell (beta
particle), energi foton < 1MeV seluruhnya diserap oleh target
-Comfton effect, only part of the original gamma energy is used
to eject a bound electron, and partly as gamma scattered
(energy gamma about 1 - 5 MeV)
-Pair Production, interaksi menghasilkan pasangan elektronpositron (energy gamma about 5 MeV), konversi foton oleh
medan magnet inti menjadi elektron dan positron--- akan
mengionisasi. Elektron dan positron akan berannihilasi
menghasilkan sinar gamma lemah (0,51 MeV) yanh diserap
target.
TUNGSTEN TARGET ATOM Z = 74
K-shell: 69.5 keV
L-shell: 12 keV
M-shell: 3 keV
N-shell: 1 keV
O-shell: 0.1 keV
Denise Moore, Sinclair Community College
BREMSSTRAHLUNG RADIATION PRODUCTION
 The projectile electron interacts with the
nuclear force field of the target tungsten atom

The electron (-) is attracted to the nucleus (+)

The electron DOES NOT interact with the orbital
shell electrons of the atom

Always produced = 100% of time
http://www.internaldosimetry.com/courses/i
ntrodosimetry/images/ParticlesBrem.JPG
BREMSSTRAHLUNG RADIATION PRODUCTION

As the electron gets close to the nucleus, it slows
down (brems = braking) and changes direction

The loss of kinetic energy (from slowing down)
appears in the form of an x-ray

The closer the electron gets to the nucleus the more
it slows down, changes direction, and the greater the
energy of the resultant x-ray

The energy of the x-ray can be anywhere from almost
0 (zero) to the level of the kVp
X- AND GAMMA-RAY INTERACTIONS
Rayleigh scattering
 Compton scattering
 Photoelectric absorption
 Pair production

RAYLEIGH SCATTERING
Incident photon interacts with and excites the
total atom as opposed to individual electrons
 Occurs mainly with very low energy diagnostic
x-rays, as used in mammography (15 to 30 keV)
 Less than 5% of interactions in soft tissue
above 70 keV; at most only 12% at ~30 keV

RAYLEIGH SCATTERING
COMPTON SCATTERING
Predominant interaction in the diagnostic
energy range with soft tissue
 Most likely to occur between photons and outer
(“valence”) shell electrons
 Electron ejected from the atom; photon
scattered with reduction in energy
 Binding energy comparatively small and can be
ignored

Dowd, S.B. Practical Radiation Protection and Applied Radiobiology
COMPTON SCATTERING
E0  Esc  Ee 
Esc 
E0
E0
1
(1  cos )
2
m0 c
COMPTON SCATTER PROBABILITIES



As incident photon energy increases, scattered
photons and electrons are scattered more toward the
forward direction
These photons are much more likely to be detected by
the image receptor, reducing image contrast
Probability of interaction increases as incident photon
energy increases; probability also depends on electron
density

Number of electrons/gram fairly constant in tissue;
probability of Compton scatter/unit mass independent of Z
RELATIVE COMPTON SCATTER PROBABILITIES
COMPTON SCATTERING




Laws of conservation of energy and momentum place
limits on both scattering angle and energy transfer
Maximal energy transfer to the Compton electron
occurs with a 180-degree photon backscatter
Scattering angle for ejected electron cannot exceed
90 degrees
Energy of the scattered electron is usually absorbed
near the scattering site
COMPTON SCATTERING



Incident photon energy must be substantially greater
than the electron’s binding energy before a Compton
interaction is likely to take place
Probability of a Compton interaction increases with
increasing incident photon energy
Probability also depends on electron density (number
of electrons/g  density)


With exception of hydrogen, total number of electrons/g
fairly constant in tissue
Probability of Compton scatter per unit mass nearly
independent of Z
PHOTOELECTRIC ABSORPTION
All of the incident photon energy is transferred
to an electron, which is ejected from the atom
 Kinetic energy of ejected photoelectron (Ec) is
equal to incident photon energy (E0) minus the
binding energy of the orbital electron (Eb)
Ec = Eo - Eb

Dowd, S.B. Practical Radiation Protection and Applied Radiobiology
PHOTOELECTRIC ABSORPTION (I-131)
PHOTOELECTRIC ABSORPTION



Incident photon energy must be greater than or equal
to the binding energy of the ejected photon
Atom is ionized, with an inner shell vacancy
Electron cascade from outer to inner shells


Characteristic x-rays or Auger electrons
Probability of characteristic x-ray emission decreases
as Z decreases

Does not occur frequently for diagnostic energy photon
interactions in soft tissue
PHOTOELECTRIC ABSORPTION (I-131)
PHOTOELECTRIC ABSORPTION

Probability of photoelectric absorption per unit
mass is approximately proportional to
3
Z /E
3
No additional nonprimary photons to degrade
the image
 Energy dependence explains, in part, why
image contrast decreases with higher x-ray
energies

PHOTOELECTRIC ABSORPTION



Although probability of photoelectric effect decreases
with increasing photon energy, there is an exception
Graph of probability of photoelectric effect, as a
function of photon energy, exhibits sharp
discontinuities called absorption edges
Photon energy corresponding to an absorption edge is
the binding energy of electrons in a particular shell or
subshell
PHOTOELECTRIC MASS ATTENUATION
COEFFICIENTS
PHOTOELECTRIC ABSORPTION



At photon energies below 50 keV, photoelectric effect
plays an important role in imaging soft tissue
Process can be used to amplify differences in
attenuation between tissues with slightly different
atomic numbers, improving image contrast
Photoelectric process predominates when lower
energy photons interact with high Z materials (screen
phosphors, radiographic constrast agents, bone)
PERCENTAGE OF COMPTON AND
PHOTOELECTRIC CONTRIBUTIONS
PAIR PRODUCTION
Can only occur when the energy of the photon
exceeds 1.02 MeV
 Photon interacts with electric field of the
nucleus; energy transformed into an electronpositron pair
 Of no consequence in diagnostic x-ray imaging
because of high energies required

PAIR PRODUCTION
ABSORPTION OF GAMMA RADIATION







Attenuation of gamma –rays in a material is exponential,
I
= Io e-µx
Io adalah Intensitas awal
I adalah intensitas gamma setelah melalui material
µ adalah koefisien absorption
X adalah ketebalan material
X1/2 = 0.693/µ
UNITS











Counts per minute
Curie (unit) , Bq
Gray (unit)
Rad (unit)
Rem (unit)
röntgen (unit)
Sverdrup (unit) (a unit of volume transport with the same symbol Sv as
Sievert)
Background radiation
Relative Biological Effectiveness
Radiation poisoning
Linear Energy Transfer
CPM AND DPM


Counts per minute (cpm) is a measure of radioactivity.
It is the number of atoms in a given quantity of
radioactive material that are detected to have decayed
in one minute.
Disintegrations per minute (dpm) is also a measure of
radioactivity. It is the number of atoms in a given
quantity of radioactive material that decay in one
minute. Dpm is similar to cpm, however the efficiency
of the radiation detector
 CPM
 DPM
~
DPM
= Ef Det
x
CPM
UNIT RADIOACTIVITY AND DOSE

One Bq is activity of a quantity of radioactive
material in which one nucleus decay per
second
SI unit untuk Radioactivity is,
Bacquerel = Bq adalah unit terkecil
1 Bq = 1 radioactive decay per second (S-1)= dis/s
1 Bq = 60 dpm
 Satuan Lama adalah Curie = Ci
,

1 Ci = 3.7 x 1010 Bq = 37 GBq
 Bq dapat dalam bentuk sbb
- kBq , MBq, GBq, TBq and PBq
Hitung : 0,25 Ci = ……dpm ?

 Pada
pengukuran zat radioaktive dgn alat
ukur akan terukur unit cps (count per
second) or cpm (count per minute) dalam
bentuk digital. Konversi cps ke absolute
activity (Bq) adalah :

Bq = cps x detektor effesiensi
 Unit of absorbed radiation dose (SI) due
to ionization radiation (X-ray) is called
Gray (Gy)
Absorbed dose (also known as total ionizing
dose, TID) is a measure of the energy deposited
in a medium by ionizing radiation. It is equal to
the energy deposited per unit mass of medium,
and so has the unit J/kg, which is given the
special name Gray (Gy).
 1 Gy of alpha radiation would be much more
biologically damaging than 1 Gy of photon
radiation

ABSORBED DOSE
Absorbed dose ; SI , Gray (Gy, kGy, etc)
 Definition : One gray is the absorption of one
joule of energy, in the form of ionizing radiation,
by one kilogram of matter


1 Gy = 1 J/kg
Absorbed dose = Gray (Gy), mengukur
deposit energi radiasi

100 rad = 1 Gy

ABSORBED DOSE
Absorbed dose is the amount of energy
absorbed into matter. The working SI unit is a
gray (Gy), while the traditional unit is rad (rad)
 1 rad = 62.4 x 106 MeV per gram
1 gray = 100 erg per gram
 1 rad = 0.01 gray
1 gray (Gy) = 100 rad
 In the United States, radiation absorbed dose,
dose equivalent, and exposure are often
measured and stated in the older units called
rad, rem, or roentgen (R)

Rongent as radiation exposure equal to the
ionization radiation will produce one esu of
electricity in one cc of dry air at oC and
standard atmosfer

1 Gy ≈ 115 R
 The röntgen was occasionally used to measure
exposure to radiation in other forms than X-rays
or gamma rays
 1 R = 2.58×10−4 C/kg (from 1 esu ≈
3.33564 × 10−10 C and the standard
atmosphere air density of ~1.293 kg/m³)

The rad (radiation absorbed dose) is a unit of
absorbed radiation dose
 A dose of 1 rad means the absorption of 100
ergs of radiation energy per gram of absorbing
material

1 Gy = 100 rad
 1 roentgen (R) = 258 microcoulomb/kg (µC/kg)


When ionising radiation is used to treat cancer,
the doctor will usually prescribe the
radiotherapy treatment in Gy. When risk from
ionising radiation is being discussed, a related
unit, the sievert is used.
EQUIVALENT DOSE








The equivalent dose (HT) is a measure of the radiation dose to
tissue where an attempt has been made to allow for the
different relative biological effects of different types of ionizing
radiation
Equivalent dose adalah absorbed dose
+ biology effect
= Rongent Equivalent Man (REM)
Equivalent dose (HTR) = Absorbed dose (Gy) x radiation
weighting factor (Wr)
Equivalent dose (SI) ---- Sievert (Sv) unit
Sievert (sv) (biasanya untuk X-ray)
100 REM = 1 Sv
1 Sv = 1 J/kg = Gy
DOSE EQUIVALENT



Dose equivalent is the absorbed dose into
biological matter taking into account the interaction
of the type of radiation and its associated linear
energy transfer through specific tissues. The
working SI unit is the sievert (Sv), while the
traditional unit is roentgen equivalent man (rem).
1Sv = 1 rads x quality factor x any other modifying
factors
1rem = 1 gray x quality factor x any other modifying
factors
1 Sv =100 roentgen equivalent man (rem)
1 rem = 0.01Sv = 10mSv
The dose equivalent is a measure of biological
effect for whole body irradiation. The dose
equivalent is equal to the product of the
absorbed dose and the Quality Factor
 The millisievert is commonly used to measure
the effective dose in diagnostic medical
procedures (e.g., X-rays, nuclear medicine,
positron emission tomography, and computed
tomography). The natural background effective
dose rate varies considerably from place to
place, but typically is around 2.4 mSv/year
 that quantity of X rays which when absorbed
will cause the destruction of the [malignant

This variation in effect is attributed to the
Linear Energy Transfer [LET] of the type of
radiation, creating a different relative biological
effectiveness for each type of radiation under
consideration
 the RBE [Q] for electron and photon radiation is
1, for neutron radiation it is 10, and for alpha
radiation it is 20
 unit of the equivalent dose is the rem (Röntgen
equivalent man); 1 Sv is equal to 100 rem, for a
quality factor Q=1

Q VALUES






Here are some quality factor values:[
Photons, all energies : Q = 1
Electrons all energies : Q = 1
Neutrons,
 energy < 10 keV : Q = 5
 10 keV < energy < 100 keV : Q = 10
 100 keV < energy < 2 MeV : Q = 20
 2 MeV < energy < 20 MeV : Q = 10
 energy > 20 MeV : Q = 5
Protons, energy > 2 MeV : Q = 5
Alpha particles and other atomic nuclei : Q = 20
OTHER USEFUL CONVERSIONS
Dose rate criteria (outside storage area):
 2.5 Sv/hr = 0.25mrem/hr
 CNSC Dose Limits (non-Nuclear Energy
Worker):
 Whole body = 1mSv/yr = 100 mrem/yr
Skin, Hands, Feet = 50 mSv/yr = 5 rem/yr

N VALUES
Here are some N values for organs and
tissues:[2]
 Gonads: N = 0.20
 Bone marrow, colon, lung, stomach: N = 0.12
 Bladder, brain, breast, kidney, liver, muscles,
oesophagus, pancreas, small intestine, spleen,
thyroid, uterus: N = 0.05
 Bone surface, skin: N = 0.01











And for other organisms, relative to humans:
Viruses, bacteria, protozoans: N ≈ 0.03 – 0.0003
Insects: N ≈ 0.1 – 0.002
Molluscs: N ≈ 0.06 – 0.006
Plants: N ≈ 2 – 0.02
Fish: N ≈ 0.75 – 0.03
Amphibians: N ≈ 0.4 – 0.14
Reptiles: N ≈ 1 – 0.075
Birds: N ≈ 0.6 – 0.15
Humans: N = 1
EFFECTIVE DOSE
Radiation source Comments
mSv/yr
mrem/yr
Natural sources
indoor radon
due to seepage of
222Rn from ground
2.0
200
radionuclides
in body
primarily 40K and
238U progeny
0.39
39
terrestrial
radiation
due to gamma-ray 0.28
emitters in ground
28
cosmic rays
roughly doubles for
2000 m gain in
elevation
0.27
27
cosmogenic
especially 14C
0.01
1
3.0
300
total (rounded)
Medical sources
Diagnostic xrays
excludes dental
examinations
0.39
39
Medical
treatments
radionuclides used in
diagnosis (only)
0.14
14
0.53
53
total
Other
consumer
products
primarily drinking
water, building
materials
0.1
10
occupational
averaged over entire
US population
0.01
1
nuclear fuel
cycle
does not include
potential reactor
accidents
0.0005
0.05
3.6
360
TOTAL (rounded)
JUDUL MAKALAH
Proses Big bang dan pembentukan alam
 Radioaktive decay untuk dating (penanggalan)
umur batuan (C-14 dan K/Ar)
 Irradiasi gamma untuk sterilisasi produk
kesehatan dan makanan
 Reaktor nuklir untuk PLTN
 Teknik radiotracer untuk Industri
 Teknik radiasi untuk pertanian
 Laser dan pemanfaatannya untuk kesehatan


Proses pemisahan (enrichment) bahan bakar
U235 dan U238
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