P6.1 Radiaiton

Question 1

Radius of atm

Answer 1

10 -10 m

Question 2

What are different isotopes of the same element, and what becomes radioactive decay?

Answer 2

Elements have a few stable isotopes, and a few unstable. These ones undergo read inactive decay to become stable (particularly nucleus), and in this process may become other elements…

4 different things can happen
Alpha beta gamma neutron

Radioactive decay is completely random

Question 3

Alpha decay?(radiation)

What is an alpha particle?

What happens when a nucleus undergoes alpha decay

Therefore what happens to the element?

Answer 3

Here an alpha particle is the same as a helium nucleus = 4 OVER 2

• THIS MEANS AN APLOHA PARTICLE HAS 2 NEUTRONS AND 2 PROTONS.
• AND SO WHEN A NUCLEUS DOES ALPHA DECAY, IT LOSES 2 PROTONS AND 2 ELECTRONS.
• nuclei who do this are normally really big as they have to lose these.
• alpha particles are big and heavy

Because it loses two protons, it forms a new element

Question 4

Beta decay

What is a beta particle

What happens when a beta particle is emitted

Answer 4

A beat particle is just a FAST MOVING ELECTRON THAT IS EMITTED FRIM THE NUCLEUS,

Basically a nucleus has no electrons, but the neutron unstable turns into a proton and an electron

however

• A NEUTRON BECOMES A PROTON WHEN ELECTRON EMITTED,
• so it can be represented as 0 over -1

(Not actually 0 but because mass 1/1800 minor)

And because a proton is added, the element changes

( beta particle= proton number increase by 1, mass number stays the same) just balance to minor

Question 5

Gamma decay?

Answer 5

• remember this gamma rays are part of the electromagnetic spectrum and are waves with the shortest wavelength but highest frequency.
• when nucleus emits gamma radiation, it just goes from EXCITED to UNEXCITED , as energy is just released in the form of this wave. Itching else changes…
• Greek Symbol some btec y

(Normally they become excited after doing alpha or beta … so then gamma hallens)

Question 6

What has the highest penetration power and how do you stop radiation (what materials)

Answer 6

1) strongest is gamma , beat and alpha

Alpha particles are blocked by paper
Beta can go through paper but blocked by a THIN ALLUMINIUM sheet

Gamma can go through all but is stopped by a thick piece of LEAD.

Question 7

What about in energy and range air detected by a Geiger Müller tube

What about background radiation?

Answer 7

1) alpha like 5 cm in air
Beta from 15 centifew meters

Gamma very long distance

Normally a gm tube will still pick up radiation if no source is put next to it- this is because of BACKGROUND RWDIATION

Question 8

What is ionising power and W ionisation, and who has the most ionising power ?

Answer 8

Ionisation is when an atom becomes positive or negative , and nuclear radiation (gamma alpha beta ) can do this, typically making an atom lose an electron (so much energy is given it eave sthe shells )

Alpha have highest ionising power (most likely to cause an atom to be ionised) and then beta then gamma.

Alpha are heavy so more kinetic ernergy and string positive forces which is why they mostly have more power.

Therefore alpha particles are likely to hit a few atoms then ionise them, but gamma hit a lot without ionising the,.

Question 9

What is neutron emission ?

(Rare but dangerous )
4th decay

What dangerous about neutron emission?

Answer 9

This is when a unstable nucleus literally meets just a neutron.

Because it has no charge it is highly ionising, and they can cause STABE atoms to become radioactive…

(A stable isotope gets a neutron, becomes unstable….)

Question 10

Quick summary of ionising power vs penetration power?

Answer 10

To ionise you need more energy, alpha particles have the most but that’s also why they have a shorter range

Alpha highest innings power, lowest penetrating power

Gamma lowest ionising power highest penetration .

Question 11

His what is the pricnicple of half life?

What is activity of a source?
How measured
What is count rate?
What is activity measured in?

Net decline?

Answer 11

Radioactive decay is a random process, and we can’t ever predict when a nucleus will decay.

The activity of a source is the amount of nuclei that decays VERY SECOND , say in an isotope. This is picked up by a Geiger muller tube, and measured in BECQUERELS (BQ).

Therefore if a source had an activity of 10 Bq, to unstable nuclei decay per second or radiation

• the nuclei decaying per second is also called count rate, yet this could also be background rwdirojnsonlicked uo by gm time is count rate

=

The half life of the source, is therefore the AVERAGE time it takes for a source activity to HALVE.

Or the half life of a source is the time it takes for half the nuclei to decay

Or the half life of a source is the time it takes for the count rate to half

Remember for net decline you need to do ratio do what left: to what was there, 1: 4

Question 12

What do you have to consider when measuring using a GM tube?

Answer 12

There is background radiation present, so you must take this away from the radiation of the source you are investigating

Question 13

What happens when electrons get energy?

And lose energy? How can this happen

Answer 13

Electrons gain energy, they can move up an energy level to a new shell. They are excited. They exact amount of energy needs to be given for them to go up a level.

The energy we term in packets are called PROTONS.

If a photon with enough energy is absorbed, it can knock an electron off- causing it to become ionised. Photons such as Gamma, uv and x Rays are ionising photons.

However, when the electron goes back to its old shell, the electron will emit exactly the same ( or atleast total the same) energy received- emitting photons as radiation.

It can lose radiation in steps of shells, but the photons will be weaker with lower wavelengths and frequencies (smaller photons) (not sure though’

Question 14

What is an emission spectrum

Answer 14

Emission spectrum shows the spectrum of photons EMITTED BY AN ATOM when it moves down an energy level

Absorption shows frequencies of spectrums that are absorbed by an atom when electrons move to excited state, and opposite is emission which sows frequencies of photons emoted whnenmoved to unexpired state

Question 15

What is different of irradiation and contamination?

What is the largest energy change

Answer 15

Irridation is when radioactive source reaches you from outside the body, but can still go into your body

Contamination is if the source reaches you from inside the body (or on the body skin) If you are contaminated you will always have the radioactive material in you.

In both cases, ionising radiation can happen, therefore DNA is as risk of getting damaged

Just before ionsiswtion

Question 16

How does ionising radiation harm you

Answer 16

Cause variation by mutation
S in DNA, which can be damaging
And also controlling cells to divide uncontrollably- cancer

Question 17

Which radiation’s are most harmful outside and insidide the body?

Answer 17

Outside the body beta and gamma radiation are the most dangerous- these two have high penetrating powers remember and can pass through the skin and into deeper organs, alpha is the safest outside

Inside the body, beta and gamma radiation is the safest. Being already in the body, they have the lowest ionising powers so would barely ionise anything and just pass out. BUT ALPHA ARE THE MOST DANGEROUS, INSIDE THEY ARE MOST IONISNG AND CAUSE DAMAGE IN SMALL AREAS.

This is why in gamma ray travers it is gamma not alpha….

Question 18

How are irridation and contamination risks measured?

What is temporary irradiation ir contamination

What can lower vs higher doses of ionising rwdiorom do?

Answer 18

For irridation, the risk of an object being irradiated. Basically, alpha radiation have the lowest irradiation risk because penetrating power lowest compared to something like gamma.

Also any object, the further away you put it, reduces its irrational risk.

2) as for contamination, if the substance a solid, the risk is less then if it was a gas as you can easily inhale that

Irrsditikn temporary, remove source and you are safe, contamination is more permanent as atoms left behind do damage…

4) lower causes cancer and mutations, higher kills the cell which causes radiation sickness if too many happens at once

Question 19

How do gamma tracers work and what you need to consider when choosing half life?

Answer 19

Some radioactive isotopes are purposefully injected into the body in order to give off gamma radiation. Then, a tracer can detect this and make an image of say an organ to help with diagnosis.

Radiographers must make sure the isotope half life is not too long, as to cause cancer risk, but not too short, to give time for the gamma tracer to bused.. something like half life 6 hours good.

Gamma is chosen because dir cns oenetrste our snd is lässt ionising

So summary
Rsdisocyive Isotope tracers sre purposeflylly injected snd s theynfolllow body they emit rsditoj which’s species gamma camera can detect, and then produce images. HELPING THEM DISGNOSE DISEASE

Question 20

Explain how doctors use a gamma knife to focus GAMMA rays to kill you our

How is damage limited

When could alpha particles be used in treatment?

Answer 20

Gamma has enough ionisng power to kill cells, so it’s used in radiotherapy.

• the radiation is directed at specific places , considering things like dosage for age of patient etc.
• However, the patient must ebs till and the rays are rotated around the tumour to reduce the dosage any one healthy cell receives around the tumour… decreasing risk of more damage.
• TIME IS GIVEN BETWEEN FIR THE CELLS TO RECOVER.

If alpha emitters are injected into a tumour high ionising means they kill all cels in local area and because penetration isn’t hat much they don’t affect healthy cells (range)

Question 21

Background radiation , percentages

List them if not (5 sources)

Answer 21

Cells have to repair against background radiation all the time

Just try to remeber FOOD DRINK, BUIKDINGS, ROCKS, ARTIFICAL, COSMIC

• 50% comes from rocks (radon gas)
• 14 % medical uses
• 0.3 % other artificial (like nuclear power)
• 10% cosmic rays
  14% from the ground and buildings
  11.5 from food and drink

Question 22

What is nuclear fission and what is it typically done on, what two ways can it be done by

How does it work along with chain reaction?

How can enery
Reduced by used ?

Answer 22

A type of neu clear reaction Süd- to release energy from LARGE UNSYABLE NUCLIE like uranium and plutonium by splitting harem into smaller (so,tiring of large unstable Neugliederns)

It can be spontaneous (happen by itself) (rare)
Or absorbing a neutron , which makes it unstable and thus splits

1) When uranium nucleus absorbs a neutron, it becomes unstable forcing it to split
2) when it splits into two, two or three neutrons are also release as well as a lot of energy and Gamma radiation. This energy is often. Given to fission products

3) the neutrons can now be absorbed by more nuclie, causing it to happen again, and happen again- chain reaction , and Esch time energy is released , enormous amount
1) now fission products move a lot due to energy they have kinetic, colliding with things around them heating them up, so you can use this to heat up water as steam to drive turbines to make electricity .

Question 23

How is fission controlled vs uncontrolled , what are problems with nuclear energy

Answer 23

Fission can be controlled by using materials that absorb some of the neutrons so it is not sn exponential amount of reactions taking place Esch time

Nuclear bomb is uncontrolled as aim is to produce as much energy as possible

)dispels I’d waste, as wastebpeosucs are highly radioactive and have long hislfnlifes, expensive to dispose safely
- cost is high of power plant and decommissioning (can take years)

Accidents like chrnoybly may Hallen

Question 24

Nculeaur fusion?

Why do Fusion if er fission

How it work?

Answer 24

Where two light nuclei join to create a large nucleus , therefore fuse

• fusion releases MUCH More Neely then fission

1) for example, two hydrogen nuclie fuse to make a hydrogen nuclie
2) problem is when you bring two nuclei together is both lsotive they repel, but under high temperatures, = large Soldes and high pressures= force close enough, they fuse,
3) these conditions are only found in suns and stars however , so not easy to replicate on earth . So far method is not profitable yet…

ALSO DOES NIT PROUCE ANY TOXIC WASET, nucleus so advantage over fission and HYDEOGEN FUEL ABNUDBANCS

Question 25

Where does energy come from in fusion?

Answer 25

The mass of products is always less then mass of reactants, but by a small amount

This small amount produces insane energy, as it converted to energy can carried away by gamma.
Calculate using e v mc 2, and because velocity of lightning is large such small mass can produce such high energy