Yeonne Greene, on 15 August 2016 - 07:50 PM, said:
I am not confusing my radiation types here, and you are being disingenuous about what is, at a high level, a correct statement. Negligible in air? 500 keV only goes about 62 m before it has lost half its intensity. Are you expecting LGRB energy levels out of crappy third-hand BattleTech equipment? Please. Gamma radiation is absorbed by matter, and the various attenuating effects you will encounter in the atmosphere as a result of that absorption (Compton scattering, pair-production among them) will make it less than economical to maintain a coherent beam. Yes, you can get around these attenuating effects by increasing the energy level, but that is neither a unique characteristic to gamma radiation nor is it something truly feasible because you start running into logistical issues in providing enough power to get a good-enough punch at the range you want. It is inefficient.
In addition, what you get in trying to deploy a high-energy gamma ray laser in atmosphere is a weapon that irradiates everything around you either directly or through secondary effects. Now, in context of the story, I believe radiation effects are the reason nuclear weapons are frowned upon in general and actually banned by the Ares conventions. With that in mind...large lasers as described would also be illegal even if they were capable of punching holes in armor at reasonable distances, since their use would render large areas uninhabitable.
What you think x-rays can do depends entirely on how and where you place the differentiator between x-ray and gamma radiation, which from my understanding is a very fuzzy area with considerable overlap. =/
Extremely high energy gamma rays also may produce photo-disintegration effects, which is not quite the same as producing fission. In both cases, though, you do end up with new materials; this is not merely "degrading the material faster," it is potentially changing its chemical composition.
I'm not sure that getting into the details here (on a game forum) is reasonable but.
The statements were made around 'gamma lasers' (ok, gasers actually to keep that abbreviation correct). Those, theoretically, function using heavy nuclei (both for more levels and more options to get to high exitation metastable states via small steps), but anyway, theoretical upper limit on gammas produces in Mössbauer-type (long life times of isomers) gaser is 150 keV (making those X-rays). And this won't work anyway as emission line anyway will be too wide.
The schemes with shot life times (as in classical lasers) suffer from same wide emission lines and lack of reflection materials or means to produce boot flash. But those schemes in therory allowed to get really high in energies, however no way of creating those were found as not a single nuclei (lighter than uranium that is) does have needed properties (even Hf, that was speculated the most). So they remain as pure speculation and are frowned upon by scientific community when are brought up.
Anyway, working schemes has energies below e+e- pair production and this energies are lower than typical distance between the nitrogen and oxygen g.s. and first exitation level (and you do not have many not g.s. nuclei in natural conditions), thus those gammas are not absorbed (so no photodisintegration). You need 20-25 MeV for this to matter. And the lower limit for photodisintegration is considered to be around 10 MeV (pure absorption with variations after). So, again, it is not quite correct to attribute X-rays and low energy gamma rays direct photodisintegration properties. Effects of gamma-rays absorption and following nuclei decay can be discussed, but the natural radiation background will do you no less. If you keep gamma beam on a target for a few month, then, yes, there will be consequences. But even after constant direct irradiation for few years materials have degraded structure, but not so much changes chemical composition (there was an experiment on ISS to check exactly that). So, while potentially a gamma quant with energy enough for nuclei changing its charge (especially in neutron abundant on neutron starved nuclei) the probabilities are way to low. Really, this even falls beyond scope of space electronics development as pure structural degradation is many orders more violent in its effects.
Yes, we keep to what a theoretical gamma laser functioning in real world can do. The fluff however can have the LL to be 1 PeV gamma laser and nothing stops them from declairing that.
As to radiation effects in air. Let's say it so. While strict rules require gamma sources to be stored in Pb reinforced vault the lab reality is that the gamma sources (Sr-133, I-131, Co-60 etc. with gammas up to 5 MeV) are stored on the table behind the wall of Pb bricks. And this goes for decades without triggering any radiation contamination alert (as when the alpha source was accidentially spilled by a student). Really, Compton scattering and other effects have their place, but the cross-section is low.
As to Ares convention... You know, a dense short laser pulse hitting a metal surface do produce high energy electrons and strong x-rays thus making shileding required on heavy industrial laser cutters. What LPL would produce I'd prefer not to get into. Too many fluff variables.
So, again, I would correct to that the scattering and absorption are different mechanisms. And for X-rays and low energy gammas the scattering is the main process of beam intensity and coherency loss.
Edited by pyrocomp, 16 August 2016 - 06:42 AM.
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