Why is the ionizing power of gamma rays very low?

[mahela007]

If gamma rays have the highest frequency, then they must have the highest energy. So why aren't they able to ionize atoms? (by removing electrons)

[insane_alien]

oh they're perfectly capable of ionization, its just that they whizz through pretty much everything without coming close enough to an electron to interact with it. this is due to their extraordinarily short wavelength which means it requires and almost direct hit to remove it from an atom.

 

with particle radiation there isn't a need for a direct hit it can just pass close by and ionize something. and is more likely to ionize a material it is passing through.

[mahela007]

so, in other words, it's just a question of probability?

[insane_alien]

yep, to a gamma photon even a lead brick is a few sparse particles in space.

 

to an alpha particle a paper sheet is like a brick wall to us.

 

in the former case its unlikely to hit something in the latter it is very likely to hit something.

[Bishadi]

If gamma rays have the highest frequency, then they must have the highest energy. So why aren't they able to ionize atoms? (by removing electrons)

 

because the mass is not capturing the exchange. Almost like light going thru a window.

 

Ionization is when mass captures a portion and the remaining is upon the environment of the associated mass.

 

for ex; a cup of water and salt, the NaCl becomes Na+ and Cl- within the body of the solution. The Na Cl can maintain a greater wavelength between the associated system; hence the whole cup will freeze at a lower surrounding temp because the solution has retained a greater state of energy (em).

[insane_alien]

huh? salt is Na+ and Cl- even when in its solid form. there is no ionization involved in forming a salt solution.

 

Ionization is when mass captures a portion and the remaining is upon the environment of the associated mass.

 

this doesn't make any sense whatsoever. ionization is when an atom or molecule gains a non neutral charge either by the addition or subtraction of electrons.

[Bishadi]

huh? salt is Na+ and Cl- even when in its solid form. there is no ionization involved in forming a salt solution.

what enables the Na and Cl to combine?

 

is it an increased state of energy? (quantum jump/bohr model)

 

what is that 'thing' that is captured to even enable any atom to increase its potential (added to the electron to jump shells)?

 

this doesn't make any sense whatsoever. ionization is when an atom or molecule gains a non neutral charge either by the addition or subtraction of electrons.

 

and so, for an electron to leave any atom, what must be 'upon' that electron?

[swansont]

Bound systems have lower energy than unbound systems. There is no "increased state of energy" around.

[John Cuthber]

"and so, for an electron to leave any atom, what must be 'upon' that electron?"

An electromagnetic force needs to act on it.

 

Anyway, if memory serves me after about 20 years of not needing to know. The answer is that the overlap integral that you can calculate from time dependent perturbation theory isn't very big.

Not very helpful as an answer, but at least it's not gibberish like Bishadi's post.

[Bishadi]

Bound systems have lower energy than unbound systems. There is no "increased state of energy" around.

 

that don't make sense logically.

 

ex.... a star is bound mass versus open space (which is of lower energy?)

 

not to mention life consumes (energy)

 

then to observe the solution seems to add NaCl; the water can then retain more energy

 

but mathematically your claim can be made to makes sense (2nd law to chemistry but not via quantum chemistry (resonant energy transfer)

 

Resonance Energy Transfer contains a large amount of cutting-edge research which has never before appeared in book form. It is the first comprehensive modern survey of the field, offering a broad, yet detailed view of the mechanisms of energy transfer. The broad range of applications of fluorescence and fluorescence energy transfer to studies in molecular biology and biotechnology ensures that resonance energy transfer will be a vital component of the new science and technology of the next millenium.

 

 

Note: Foerster coupling (Hamiltonian- energy shift between mass) in this frame the energy is the specimen versus the mass (product.)

 

 

this thread was asking why gamma is not ionizing mass

 

the idea is that the mass is the reason because every atom has electrons (per se) and the mass, volume and environment is quite relevant to how each element is affected when any em (gamma or otherwise) is imposed

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"and so, for an electron to leave any atom, what must be 'upon' that electron?"

An electromagnetic force needs to act on it.

 

you can quote with [ quote ] (front of clip) then [ /quote] post clip (remove spaces)

 

but nice to see you are sharing the agreement

 

 

Anyway, if memory serves me after about 20 years of not needing to know. The answer is that the overlap integral that you can calculate from time dependent perturbation theory isn't very big.

Not very helpful as an answer, but at least it's not gibberish like Bishadi's post.

 

are postings of such insults normal around here?

 

 

and since your memory will not be able to convey the answer without your insults;

 

perhaps be nice and ask questions before posting such especially when yu share the agreement to the underlying principle.

Edited August 4, 2009 by Bishadi
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[Klaynos]

because the mass is not capturing the exchange. Almost like light going thru a window.

 

It's nothing like that, when visible photons pass through glass they are absorbed and re-emitted many many times.

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The answer is that the overlap integral that you can calculate from time dependent perturbation theory isn't very big.

 

It's fantastically small.

[Bishadi]

It's nothing like that, when visible photons pass through glass they are absorbed and re-emitted many many times.

 

 

what is 'nothing like that'?

 

 

perhaps a few more lines of education;

 

 

When a gamma ray passes through matter, the probability for absorption in a thin layer is proportional to the thickness of that layer. This leads to an exponential decrease of intensity with thickness. The exponential absorption holds only for a narrow beam of gamma rays. If a wide beam of gamma rays passes through a thick slab of concrete, the scattering from the sides reduces the absorption.

 

 

Here, μ = nσ is the absorption coefficient, measured in cm−1, n the number of atoms per cm3 in the material, σ the absorption cross section in cm2 and d the thickness of material in cm.

 

In passing through matter, gamma radiation ionizes via three main processes: the photoelectric effect, Compton scattering, and pair production.

 

Photoelectric effect:

 

This describes the case in which a gamma photon interacts with and transfers its energy to an atomic electron, ejecting that electron from the atom. The kinetic energy of the resulting photoelectron is equal to the energy of the incident gamma photon minus the binding energy of the electron. The photoelectric effect is the dominant energy transfer mechanism for x-ray and gamma ray photons with energies below 50 keV (thousand electron volts), but it is much less important at higher energies.

 

 

Compton scattering:

 

This is an interaction in which an incident gamma photon loses enough energy to an atomic electron to cause its ejection, with the remainder of the original photon's energy being emitted as a new, lower energy gamma photon with an emission direction different from that of the incident gamma photon. The probability of Compton scatter decreases with increasing photon energy. Compton scattering is thought to be the principal absorption mechanism for gamma rays in the intermediate energy range 100 keV to 10 MeV. Compton scattering is relatively independent of the atomic number of the absorbing material, which is why very dense metals like lead are only modestly better shields, on a per weight basis, than are less dense materials (as mentioned previously).

 

 

Pair production:

 

This become possible with gamma energies exceeding 1.02 MeV, and becomes important as an absorption mechanism at energies over about 5 MeV (see illustration at right, for lead). By interaction with the electric field of a nucleus, the energy of the incident photon is converted into the mass of an electron-positron pair. Any gamma energy in excess of the equivalent rest mass of the two particles (1.02 MeV) appears as the kinetic energy of the pair and the recoil nucleus. At the end of the positron's range, it combines with a free electron. The entire mass of these two particles is then converted into two gamma photons of at least 0.51 MeV energy each (or higher according to the kinetic energy of the annihilated particles).

 

 

but to focus on glass and what 'the community' represents then allow the same 'common sense' approach

 

 

The atoms that bind together to make the molecules of any particular substance have electrons, usually lots of them. When photons come in contact with these electrons, the following can occur:

 

•An electron absorbs the energy of the photon and transforms it (usually into heat)

 

•An electron absorbs the energy of the photon and stores it (this can result in luminescence, which is called fluorescence if the electron stores the energy for a short time and phosphorescence if it stores it for long time)

 

•An electron absorbs the energy of the photon and sends it back out the way it came in (reflection)

 

•An electron cannot absorb the energy of the photon, in which case the photon continues on its path (transmitted)

 

 

Most of the time, it is a combination of the above that happens to the light that hits an object. The electrons in different materials vary in the range of energy that they can absorb. A lot of glass, for example, blocks out ultraviolet (UV) light. What happens is the electrons in the glass absorb the energy of the photons in the UV range while ignoring the weaker energy of photons in the visible light spectrum. If the electrons absorb the energy of any portion of the visible spectrum, the light that transmits through will appeared colored according to the portion of the spectrum absorbed. In fact, the color of any object is a direct result of what levels of energy the electrons in the substance will absorb!

 

just the basics on 'how stuff works'

 

even when the local gang is stubborn; reality will stand up all by itself!

[insane_alien]

so whats the source of where you copy and pasted that from?

 

btw, klaynos is somewhat knowledgable about this. he does have a degree on it.

[DJBruce]

His first article is directly from the all mighty and infallible Wikipedia. His second is also from Wikipedia.

 

For my money I take Klaynos over Wiki any day.

[Bishadi]

so whats the source of where you copy and pasted that from?

 

http://science.howstuffworks.com/question404.htm

 

 

btw, klaynos is somewhat knowledgable about this. he does have a degree on it.

 

 

 

i like any honest comment, but degree or no degree a 14 yr old can have a greater amount of depth, now a days because of the internet; then even einstein feynman and hawking combined.

 

when a claim of 'nothing like that' is made against something i personally have researched; then they best know what they talking about and be capable to the last word (math)

 

i did not comment to mislead and will always be responsible before posting on any subject.

 

I found his comment erroneous and have provided information to assist others in overcoming the complacent as well.

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His first article is directly from the all mighty and infallible Wikipedia. His second is also from Wikipedia.

 

For my money I take Klaynos over Wiki any day.

 

 

shall we ass.u.me that this forum is more of a personality contest?

 

 

i offered wiki to assist the rookies with the basics.... (heck i thought each in this section would already know most everything posted) (we haven't even played tic tac toe......... yet)

[Klaynos]

When a gamma ray photon is absorbed, the process os absorption is the same (but with higher energies) than that of visible like being absorbed and then re-emitted for visible light. There are some very serious differences though, and they are what makes your statement wrong.

 

Visible photons come out of the glass because they are re-emitted.

Gamma ray photons come out of materials because they are NEVER absorbed (if they do they don't come out), this is why their ionising ability is so low, because they very rarely get absorbed. Saying this is the same as glass is clearly wrong.

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Please note that if you are using sources to copy from you MUST provide links to the original source

[Bishadi]

When a gamma ray photon is absorbed, the process os absorption is the same (but with higher energies) than that of visible like being absorbed and then re-emitted for visible light.

correct and some mass can absorb some energy levels while others can't

 

There are some very serious differences though, and they are what makes your statement wrong.

which statement and why; please?!

 

help me learn what is failing your understanding so i can learn how to comprehend you and maybe others who feel the same way.

 

Visible photons come out of the glass because they are re-emitted.

depends on the material mass of the glass; in my view

 

Gamma ray photons come out of materials because they are NEVER absorbed

then why use "irradiation" in medical fields?

 

would that mean no more cancer from (per se) gamma ray bursts or even nuclear weapons?

 

(if they do they don't come out), this is why their ionising ability is so low, because they very rarely get absorbed. Saying this is the same as glass is clearly wrong.

 

 

for some reason 'clearly wrong' cannot be used in your comment without your credibility being questioned.

Please note that if you are using sources to copy from you MUST provide links to the original source

 

okey dokey...... that is my favorite place to dwell; in evidence

[Klaynos]

correct and some mass can absorb some energy levels while others can't

 

It is FAR more complicated than just mass. Have a look at fermi's golden rule.

 

http://en.wikipedia.org/wiki/Fermi%27s_golden_rule

 

Also, perturbation theory, and overlap intergral.

 

which statement and why; please?!

 

This one:

 

because the mass is not capturing the exchange. Almost like light going thru a window.

 

Why? For the reasons discussed above, the process of no interaction and absorption and re-emission are fundamentally different.

 

help me learn what is failing your understanding so i can learn how to comprehend you and maybe others who feel the same way.

 

depends on the material mass of the glass; in my view

 

It is more complicated than that, please see above. Permittivity and permeability of materials depends on many many many things.

 

then why use "irradiation" in medical fields?

 

We are discussing why gamma rays are so unionising despite their high energy. We are not saying they NEVER ionising things.

 

would that mean no more cancer from (per se) gamma ray bursts or even nuclear weapons?

 

Please see the above statement.

 

for some reason 'clearly wrong' cannot be used in your comment without your credibility being questioned.

 

Please see the reasons I give above, why the two situations are fundamentally different.

[Bishadi]

It is FAR more complicated than just mass.

 

i guess if you want it to be;

 

did you miss this

 

the idea is that the mass is the reason because every atom has electrons (per se) and the mass, volume and environment is quite relevant to how each element is affected when any em (gamma or otherwise) is imposed

 

Have a look at fermi's golden rule.

 

http://en.wikipedia.org/wiki/Fermi%27s_golden_rule

 

Also, perturbation theory, and overlap intergral.

 

to calculate a probability?

 

Why? For the reasons discussed above, the process of no interaction and absorption and re-emission are fundamentally different.

maybe the descriptions are different but the process is not; the process exists, the descriptions vary.

 

It is more complicated than that, please see above. Permittivity and permeability of materials depends on many many many things.

exaclty and why 'clearly wrong' was made moot

 

We are discussing why gamma rays are so unionising despite their high energy. We are not saying they NEVER ionising things.

you keep capitalizing NEVER, that was my first.

 

you said gamma 'never'.......blah quote blah """Gamma ray photons come out of materials because they are NEVER absorbed"""

 

 

Please see the above statement.

you keep saying that and i am getting a kink in my neck

Please see the reasons I give above, why the two situations are fundamentally different.

you post fermi probabilities where volume, environment and time is relevant but for some reason did not comprehend; i already know that.

 

do i need to continue looking up!

[Klaynos]

i guess if you want it to be;

 

Not if I want it to be, in reality. For the simplest thing look at the refractive indices of simple gases at STP and how they vary and note how it is not related to mass.

 

did you miss this

 

the idea is that the mass is the reason because every atom has electrons (per se) and the mass, volume and environment is quite relevant to how each element is affected when any em (gamma or otherwise) is imposed

 

I didn't miss it.

 

to calculate a probability?

 

Yes, we are discussing why gamma is not considered to be as ionising, it is in no way for the same reason as glass is visible at optical frequencies.. Therefore the probabilities are massively important.

 

maybe the descriptions are different but the process is not; the process exists, the descriptions vary.

 

No. In one of them there is NO absorption (for the gas of the photon coming out the other side), in the other there are many events that result in the photon coming out the other side.

 

exaclty and why 'clearly wrong' was made moot

 

Not really, this is a different argument you are getting us into here. We are discussing why gamma is not ionising, it is in no way for the same reason as glass is visible at optical frequencies.

 

you keep capitalizing NEVER, that was my first.

 

The probability is fantastically small when compared to other more ionising radiations (please see the first post).

 

you said gamma 'never'.......blah quote blah """Gamma ray photons come out of materials because they are NEVER absorbed"""

 

If they come out the other side they are never absorbed, whereas optical frequency photons through glass are absorbed and re-emitted. I clearly clarified this point in brackets after I first said "NEVER" to ensure this point did not arise.

 

you keep saying that and i am getting a kink in my neck

 

It saves me writing the same text after two statements. I'd assumed you'd already read what I had written.

 

you post fermi probabilities where volume, environment and time is relevant but for some reason did not comprehend; i already know that.

 

do i need to continue looking up!

 

I'd suggest you need to re-read about them and the first post, and understand that no absorption is different to absorption followed by re-emission.

[Bishadi]

Not if I want it to be, in reality. For the simplest thing look at the refractive indices of simple gases at STP and how they vary and note how it is not related to mass.

then what molar content?

 

it seems you missed something there; the stp is quite relevant to the mass

 

Yes, we are discussing why gamma is not considered to be as ionising, it is in no way for the same reason as glass is visible at optical frequencies.. Therefore the probabilities are massively important.

i said 'almost' in the sense that gamma goes thru most everything just like light does thru a glass; it was to allow the conceptualization of observing the mass as the most relevant factor.

 

No. In one of them there is NO absorption (for the gas of the photon coming out the other side), in the other there are many events that result in the photon coming out the other side.

what 'many events'?

 

and why NO absorbtion? ("""(for the gas of the photon coming out the other side), """)

 

 

Not really, this is a different argument you are getting us into here. We are discussing why gamma is not ionising, it is in no way for the same reason as glass is visible at optical frequencies.

sure it is, the mass imposed is quite relevant. Along with the environment........... what is so tough about that?

 

 

The probability is fantastically small when compared to other more ionising radiations (please see the first post).

the probability can be adjusted by changing the conditions (mass, volume, environment) even as the STP (condition; molar standards) share

If they come out the other side they are never absorbed, whereas optical frequency photons through glass are absorbed and re-emitted.

perhaps look up a weeeee bit on masers and find that mass can change the wavelength as the energy is passing through (kind of like how water slows light (standard))

 

I'd suggest you need to re-read about them and the first post, and understand that no absorption is different to absorption followed by re-emission.

 

and no absorption and/or absorption followed by re-emission; is still based on the mass, volume and environment; nothing has changed

[Klaynos]

then what molar content?

 

Well, things like the electron configuration.

 

it seems you missed something there; the stp is quite relevant to the mass

 

Urm what? How does having all the gases at STP alter their masses?

 

i said 'almost' in the sense that gamma goes thru most everything just like light does thru a glass; it was to allow the conceptualization of observing the mass as the most relevant factor.

 

My argument is that; the way that visible light goes through glass (absorption and re-emission), is fundamentally different to the way gamma photons passes through matter, with no interactions.

 

what 'many events'?

 

Each absorption and re-emission.

 

and why NO absorbtion? ("""(for the gas of the photon coming out the other side), """)

 

Case, not gas, it was a typo.

 

If a gamma photon is absorbed it does not come out the other side, in the case of glass a visible photons will be absorbed and re-emitted many times.

 

sure it is, the mass imposed is quite relevant. Along with the environment........... what is so tough about that?

 

That the mass isn't the only thing involved and IIRC is dwarfed by other factors.

 

the probability can be adjusted by changing the conditions (mass, volume, environment) even as the STP (condition; molar standards) share

perhaps look up a weeeee bit on masers and find that mass can change the wavelength as the energy is passing through (kind of like how water slows light (standard))

 

The problem is how do you change the mass of a material without changing all of it's other features as well? If you look at the refractive indices for simple gasses you can see there is not a relationship with mass.

 

and no absorption and/or absorption followed by re-emission; is still based on the mass, volume and environment; nothing has changed

 

This is a different argument. Please the discussion is why gamma radiation is not as ionising despite it's high energy, the reason for this is NOT the same as why visible light passes through glass.

[Bishadi]

Well, things like the electron configuration.

for STP........... ??????????????????

 

Urm what? How does having all the gases at STP alter their masses?

 

Wow! I thought you were talking about 'molar volume of gas' (the standard to the system; standard conditions for pressure and temperature)

 

you said **For the simplest thing look at the refractive indices of simple gases at STP and how they vary and note how it is not related to mass.***

 

and i share that 'it is relevant' and even to establish the stp, the relevance is represented.

 

 

My argument is that; the way that visible light goes through glass (absorption and re-emission), is fundamentally different to the way gamma photons passes through matter, with no interactions.

then which way.....?

 

it is all em (electric and magnetic fields at perpendicular planes) what is so different?

 

The problem is how do you change the mass of a material without changing all of it's other features as well? If you look at the refractive indices for simple gasses you can see there is not a relationship with mass.

you can't have a gas without mass.

 

please look up masing; you are not helping and simply arguing without basis

 

 

This is a different argument. Please the discussion is why gamma radiation is not as ionising despite it's high energy, the reason for this is NOT the same as why visible light passes through glass.

 

i used the glass as an analogy

 

you state the reason as being 'not the same as why visible light passes through glass'..................

 

i didn't say it was the same; i claimed that the mass is as relevant as the glass is to light and for some reason you post STP and mention gas but again fail to observe the mass of the gas (pressure.. temp...: environment) of your rebuttal

[Klaynos]

for STP........... ??????????????????

 

 

 

Wow! I thought you were talking about 'molar volume of gas' (the standard to the system; standard conditions for pressure and temperature)

 

STP, standard temp and pressure, you seem to know that. If you take gasses at STP, and you measure the refractive index you will find it varies, and it varies not with mass.

 

you said **For the simplest thing look at the refractive indices of simple gases at STP and how they vary and note how it is not related to mass.***

 

and i share that 'it is relevant' and even to establish the stp, the relevance is represented.

 

I'm afraid I don't understand that sentence.

 

then which way.....?

 

it is all em (electric and magnetic fields at perpendicular planes) what is so different?

 

One of them interacts many many times, one of them does not interact at all.

 

you can't have a gas without mass.

 

I never claimed you could, you can measure the mass and refractive index for a given situation and then change the gas. You will find some light gasses have a lower refractive index than some heavy gasses, but some heavy gasses will have a lower refractive index than light gasses.

 

please look up masing; you are not helping and simply arguing without basis

 

I understand MASERs thanks.

 

i used the glass as an analogy

 

The analogy is wrong. It is a very very poor analogy.

 

you state the reason as being 'not the same as why visible light passes through glass'..................

 

i didn't say it was the same;

 

You claimed it was very similar to it, which it is not.

 

i claimed that the mass is as relevant as the glass is to light and for some reason you post STP and mention gas but again fail to observe the mass of the gas (pressure.. temp...: environment) of your rebuttal

 

I think I see what you are getting at here. But all the visible photons that pass through glass have been absorbed. None of the gamma photons that pass through will have been. Please note the condition that they pass through.

[Bishadi]

STP, standard temp and pressure, you seem to know that. If you take gasses at STP, and you measure the refractive index you will find it varies, and it varies not with mass.

what is the ref index of a diamond?

 

in comparison to the He gas for dual noble gas maser?

 

I'm afraid I don't understand that sentence.

STP shares that the molar scale of the mass is relevant. You just don't see it that way.

 

I never claimed you could, you can measure the mass and refractive index for a given situation and then change the gas. You will find some light gasses have a lower refractive index than some heavy gasses, but some heavy gasses will have a lower refractive index than light gasses.

i know and the STP and mass of the gas is absolutely relevant to the differences.

The analogy is wrong. It is a very very poor analogy.

so is bringing up STP and suggestin the mass of the gas is no mass to observe

 

or even this line

 

***One of them interacts many many times, one of them does not interact at all.****

 

in which you share nothing of evidence to any of the statements

 

 

I think I see what you are getting at here. But all the visible photons that pass through glass have been absorbed.

not neccessarily

 

see this item on polarizers and a patent in the works

 

http://www.freshpatents.com/-dt20090702ptan20090168172.php

 

None of the gamma photons that pass through will have been. Please note the condition that they pass through.

 

i am, the mass is most relevant and you just don't like that