Topic: NASA working on radiation shielding material+

[Stormbringer]

It also works as a structural material for the hulls of stations or ships.


http://space.com/scienceastronomy/nasa_radiation_031201.html
 

[Sirgod]

From the article:  

Quote:
 The shield, composed of several sheets of polyethylene heavily impregnated with hydrogen, is called a material composite, said Raj Kaul, an NSSTC materials scientist. The hydrogen breaks down, or diffuses, harmful radiation that could cause cancer by reducing heavy ions into lighter ones.

that's very interesting. It makes one wonder, If scientest have exposed all the various elemnts to Differant doses of Radiation to see what the effects are? I'm sure they have, and It's probably a juveniel question, But If so I do wonder what the results where.

Stephen

[Stormbringer]

I'm not an expert on that but I'd say it depends on the energy of the radiation. At higher radiation levels actual transmutation of the nucleus either by breaking up the nucleus or adding particles. This can lead to induced radioactivity in the materials. Of course ionization where electrons are knocked up in energy levels or even out all together, possible altering the structure of composite materials. There are a range of possibilities and given a large enough sample all of them occur; with some types of reaction happening more often than others. You know what? Death merchant is a materials engineer. I think I'll defer to him to answer this one.

[Death_Merchant]

My expertise is more mechanical deformation and metallurgy. I know only the basics regarding radiation.

But here goes

The mechanism they are employing is ionization (in this case, forming a cation by losing an electron through a high energy particle collision). The susceptibility to such ionization is measured (and on most Periodic Tables) as the first Ionization Potential. The ionization potential, I, of an atom is basically the energy that the gaseous atom must absorb in order for its most loosely held electron to become separated. As a general rule, ionization energies decrease as the size of the atoms increase (ie the loosest electron is less tightly bound in a big atom).

I assume they are using H2 to target higher energies typical of gamma rays. (the ionization potential of H is 13.598 eV). Sounds like they are creating their "composite" by bubbling H2 while forming the polyethylene sheet. Think of a miniaturized "bubble wrap" with H2 instead of air.

This type of shielding would gradually loose effectiveness as more and more H2 is ionized.  

[SL-Punisher]

And the different types of radiation have different penetrating power. Alpha waves are stopped my a piece of paper, beta waves are stopped by a thin concrete block. Gamma rays are stopped by a foot or so of solid steel.  

[Stormbringer]

Well, gamma rays are not completely stopped by steel some always gets through. the thicker the shielding the less that gets through; depending on the density of the shielding. for x rays 9 feet of water equals one inch of lead, 3 feet of concrete or perhaps 6 inches of steel. Gamma rays are more penetrating than x rays. Cosmic rays are more penetrating still. for the materials i mentioned each thickness reduces the radiation getting through by 50%. each additional thickness reduces the remaining bit 50 percent more. Rather like half lifes. This is due to the radiation wave hitting a nucleus. the denser the material the more likely that is to happen but all atoms are mostly empty space so some radiation is not stopped.  For the particle radiation (alpha and Beta) electrical and magnetic fields are sufficient to stop them. thus alphas are stopped by skin or paper;  betas are simply electrons and are not really worth bothering about much. Alphas (helium nuclei) will do damage but can actually be dusted off before they cause harm.  

[NJAntman]

Ah, the joys of space travel. Here I am wondering how they are going to dispose of this stuff.  Would it be tritium after its' usefullness has been played out? H3 trapped in a plastic sheet, nice; Yucca Mountain is going to fill up quick.

I forgot about the big yellow incinerator in space.

 

[Stormbringer]

It also works as a structural material for the hulls of stations or ships.


http://space.com/scienceastronomy/nasa_radiation_031201.html
 

[Sirgod]

From the article:  

Quote:
 The shield, composed of several sheets of polyethylene heavily impregnated with hydrogen, is called a material composite, said Raj Kaul, an NSSTC materials scientist. The hydrogen breaks down, or diffuses, harmful radiation that could cause cancer by reducing heavy ions into lighter ones.

that's very interesting. It makes one wonder, If scientest have exposed all the various elemnts to Differant doses of Radiation to see what the effects are? I'm sure they have, and It's probably a juveniel question, But If so I do wonder what the results where.

Stephen

[Stormbringer]

I'm not an expert on that but I'd say it depends on the energy of the radiation. At higher radiation levels actual transmutation of the nucleus either by breaking up the nucleus or adding particles. This can lead to induced radioactivity in the materials. Of course ionization where electrons are knocked up in energy levels or even out all together, possible altering the structure of composite materials. There are a range of possibilities and given a large enough sample all of them occur; with some types of reaction happening more often than others. You know what? Death merchant is a materials engineer. I think I'll defer to him to answer this one.

[Death_Merchant]

My expertise is more mechanical deformation and metallurgy. I know only the basics regarding radiation.

But here goes

The mechanism they are employing is ionization (in this case, forming a cation by losing an electron through a high energy particle collision). The susceptibility to such ionization is measured (and on most Periodic Tables) as the first Ionization Potential. The ionization potential, I, of an atom is basically the energy that the gaseous atom must absorb in order for its most loosely held electron to become separated. As a general rule, ionization energies decrease as the size of the atoms increase (ie the loosest electron is less tightly bound in a big atom).

I assume they are using H2 to target higher energies typical of gamma rays. (the ionization potential of H is 13.598 eV). Sounds like they are creating their "composite" by bubbling H2 while forming the polyethylene sheet. Think of a miniaturized "bubble wrap" with H2 instead of air.

This type of shielding would gradually loose effectiveness as more and more H2 is ionized.  

[SL-Punisher]

And the different types of radiation have different penetrating power. Alpha waves are stopped my a piece of paper, beta waves are stopped by a thin concrete block. Gamma rays are stopped by a foot or so of solid steel.  

[Stormbringer]

Well, gamma rays are not completely stopped by steel some always gets through. the thicker the shielding the less that gets through; depending on the density of the shielding. for x rays 9 feet of water equals one inch of lead, 3 feet of concrete or perhaps 6 inches of steel. Gamma rays are more penetrating than x rays. Cosmic rays are more penetrating still. for the materials i mentioned each thickness reduces the radiation getting through by 50%. each additional thickness reduces the remaining bit 50 percent more. Rather like half lifes. This is due to the radiation wave hitting a nucleus. the denser the material the more likely that is to happen but all atoms are mostly empty space so some radiation is not stopped.  For the particle radiation (alpha and Beta) electrical and magnetic fields are sufficient to stop them. thus alphas are stopped by skin or paper;  betas are simply electrons and are not really worth bothering about much. Alphas (helium nuclei) will do damage but can actually be dusted off before they cause harm.  

[NJAntman]

Ah, the joys of space travel. Here I am wondering how they are going to dispose of this stuff.  Would it be tritium after its' usefullness has been played out? H3 trapped in a plastic sheet, nice; Yucca Mountain is going to fill up quick.

I forgot about the big yellow incinerator in space.

 

[Stormbringer]

It also works as a structural material for the hulls of stations or ships.


http://space.com/scienceastronomy/nasa_radiation_031201.html
 

[Sirgod]

From the article:  

Quote:
 The shield, composed of several sheets of polyethylene heavily impregnated with hydrogen, is called a material composite, said Raj Kaul, an NSSTC materials scientist. The hydrogen breaks down, or diffuses, harmful radiation that could cause cancer by reducing heavy ions into lighter ones.

that's very interesting. It makes one wonder, If scientest have exposed all the various elemnts to Differant doses of Radiation to see what the effects are? I'm sure they have, and It's probably a juveniel question, But If so I do wonder what the results where.

Stephen

[Stormbringer]

I'm not an expert on that but I'd say it depends on the energy of the radiation. At higher radiation levels actual transmutation of the nucleus either by breaking up the nucleus or adding particles. This can lead to induced radioactivity in the materials. Of course ionization where electrons are knocked up in energy levels or even out all together, possible altering the structure of composite materials. There are a range of possibilities and given a large enough sample all of them occur; with some types of reaction happening more often than others. You know what? Death merchant is a materials engineer. I think I'll defer to him to answer this one.

[Death_Merchant]

My expertise is more mechanical deformation and metallurgy. I know only the basics regarding radiation.

But here goes

The mechanism they are employing is ionization (in this case, forming a cation by losing an electron through a high energy particle collision). The susceptibility to such ionization is measured (and on most Periodic Tables) as the first Ionization Potential. The ionization potential, I, of an atom is basically the energy that the gaseous atom must absorb in order for its most loosely held electron to become separated. As a general rule, ionization energies decrease as the size of the atoms increase (ie the loosest electron is less tightly bound in a big atom).

I assume they are using H2 to target higher energies typical of gamma rays. (the ionization potential of H is 13.598 eV). Sounds like they are creating their "composite" by bubbling H2 while forming the polyethylene sheet. Think of a miniaturized "bubble wrap" with H2 instead of air.

This type of shielding would gradually loose effectiveness as more and more H2 is ionized.  

[SL-Punisher]

And the different types of radiation have different penetrating power. Alpha waves are stopped my a piece of paper, beta waves are stopped by a thin concrete block. Gamma rays are stopped by a foot or so of solid steel.  

[Stormbringer]

Well, gamma rays are not completely stopped by steel some always gets through. the thicker the shielding the less that gets through; depending on the density of the shielding. for x rays 9 feet of water equals one inch of lead, 3 feet of concrete or perhaps 6 inches of steel. Gamma rays are more penetrating than x rays. Cosmic rays are more penetrating still. for the materials i mentioned each thickness reduces the radiation getting through by 50%. each additional thickness reduces the remaining bit 50 percent more. Rather like half lifes. This is due to the radiation wave hitting a nucleus. the denser the material the more likely that is to happen but all atoms are mostly empty space so some radiation is not stopped.  For the particle radiation (alpha and Beta) electrical and magnetic fields are sufficient to stop them. thus alphas are stopped by skin or paper;  betas are simply electrons and are not really worth bothering about much. Alphas (helium nuclei) will do damage but can actually be dusted off before they cause harm.