Weird meson thoughts

[Carlobrand]

Meson weapons: you make a meson, maybe by crashing protons together or something, or maybe by TL11 they've figured out the physics enough to induce mesons in some way - who knew we could do lasers in 1880? You get it up to relativistic speed - cause the thing's lifespan is in fractions of microseconds; likely you did that in the process of making them, cause you really, really didn't have much time for that. You get it over to the target; takes a fraction of a second 'cause, after all, you just accelerated this thing to relativistic speed. It decays, most likely into gamma photons (and other stuff, but I don't want to get complicated). The gamma photons go out and interact with the matter in the area, making it very unhappy.

So here's the thing: a lot of the energy you spent went into getting the thing to relativistic speed, no? The thing decays into gamma photons ; it doesn't care how fast it's going when it does it. Energy cannot be lost, but a photon is a photon - it won't go faster, it just gets more energetic. Do we now have a directional event? Is the near-C meson going to decay into gamma photons all traveling in one direction? How are these very high energy gammas interacting with the local atoms - electron-positron pairs and wildly accelerated emiting nuclei? Are those atoms in turn being accelerated to speeds that will smash other atoms?

Near as I can tell, we're basically looking at a roughly bell-curve-shaped area suddenly incandescing into radioactive plasma.

 

[tjoneslo]

Near as I can tell, we're basically looking at a roughly bell-curve-shaped area suddenly incandescing into radioactive plasma.

The real problem with meson weapons is this is wrong. Mesons
(all 32 types) decay in a 1/N curve like all radioactive decay. So most of the explosion is taking place in your accelerator.

There are two ways to get around this. First is the nuclear damper, assuming it works on meson decay times. Your meson accelerator chamber has a strong positive node set up in it, which then follows the accelerator out of the ship. As the damper field decays, the mesons quickly follow suit. Now you get something closer to the bell curve decay. With this version the meson screen is a version of the nuclear damper tuned to the meson decay process.

The other problem is that the pion decay into a pair of gamma rays, going in opposite directions, usually randomly. So even if you get the gamma rays to line up to cook the target, you have an equal number heading back at you.

The second way and my favorite answer involves Dr. Robert Meson (for whom the weapon is named), a researcher as part of the J3 effort discovers you can induce a jump field around a small region of space (say a few hundred pions or positrons), have the jump field accelerated out in a specific direction, only to have the field decay up to a minute or so later. Since the jump field isn't maintained properly, the results are a spray of the original particles, their decay products, and a host of virtual particles trapped when the jump field formed. The Meson screen is a field which causes the jump field for these little pockets to decay spontaneously. This technology later evolves into the Jump Projector and Jump Damper (as shown in the MT rules).

 

[whulorigan]

The real problem with meson weapons is this is wrong. Mesons (all 32 types) decay in a 1/N curve like all radioactive decay. So most of the explosion is taking place in your accelerator.

Correct. This is a conceptual problem with the meson gun. You would have to have the gun (and firing ship) screened in some way.

First is the nuclear damper, assuming it works on meson decay times. Your meson accelerator chamber has a strong positive node set up in it, which then follows the accelerator out of the ship. As the damper field decays, the mesons quickly follow suit. Now you get something closer to the bell curve decay. With this version the meson screen is a version of the nuclear damper tuned to the meson decay process.

The other problem is that the pion decay into a pair of gamma rays, going in opposite directions, usually randomly. So even if you get the gamma rays to line up to cook the target, you have an equal number heading back at you.

In CT, the Meson Gun is clearly described as using pi-neutral mesons (π⁰). Neutral pions decay via electromagnetism, as a π⁰ is composed of a quark and its own antiquark. They mutually annihilate each other internally in a very short period of time, producing gamma photons. The problem is that since the π⁰ decays electromagnetically, no nuclear force manipulation (strong or weak) will be of any use in manipulating a π⁰ (including a meson screen based on nuclear field manipulation).

In later publications (some of MJD's material I believe, as well as T5), the Meson Gun is described as producing both mesons (charged pions) and muons. Now, if the gun uses positive (π⁺) and negative (π^-) pions, they are not composed of quarks and their own antiquarks (they are different antiquarks and quarks). Thus, these π⁺ and π^- do not decay via internal annihilation, but rather via the Weak Nuclear Force into anti-muons (μ⁺) and muons (μ^-), respectively (with accompanying neutrinos). These muons further decay (via Weak Interaction) into positrons and electrons, respectively (again with accompanying neutrinos). So in the final analysis, you have π⁺ and π^- decaying to produce beta rays (positrons & electrons), gamma rays (some of the particles & antiparticles will annihilate, as well as positrons striking the target ship), and neutrinos.

To make the gun work:

1) You produce an initial batch of charged pions and let them decay to muons;

2) You accelerate a second group of charged pions down your accelerator barrel, and let them "pick-up" oppositely charged muons along the way. This creates an exotic atom of "muonic pionium"; (either π⁺ / μ^- or π^- / μ⁺, which when combined are electrically neutral (just like a hydrogen atom).
​

This "exotic atom" then becomes the weapon's beam. Note that both the muons and pions will be manipulatable via the Weak-Interaction (i.e. Nuclear Dampers and Meson Screens are both of use), and you solve the problem of how to accelerate a neutral particle in the wepaon barrel, as well as the problem of how to keep charged particles from mutually repelling once the beam has left the muzzle of the weapon.

Note also that whereas the π⁰ decays very quickly, both the charged pions and muons have a much longer half-life. Also, muons are one of the particles that penetrate very deeply into matter before being stopped.

 

[Carlobrand]

The real problem with meson weapons is this is wrong. Mesons
(all 32 types) decay in a 1/N curve like all radioactive decay. So most of the explosion is taking place in your accelerator.

1/N means? Half life? Half decay in the indicated time, then half again, and so forth? I suspect I used the wrong word with bell curve - I thought some might decay prematurely.

Isn't the point of the acceleration to bring the decay events to the desired location before the bulk of them decay? Am I to understand that most of the decay events are instantaneous?

...The other problem is that the pion decay into a pair of gamma rays, going in opposite directions, usually randomly. So even if you get the gamma rays to line up to cook the target, you have an equal number heading back at you. ...

Okay, but if it's happening inside a target, then the photons headed back at you are encountering the target before they escape to space and start heading your way, and there's a lot of space between you and him for them to spread into. If the particle decays after being accelerated to relativistic speeds, are the resulting gammas going to be red-shifted/blue-shifted? (and how does that work with a gamma emitting at a right angle??)

...

To make the gun work:

1) You produce an initial batch of charged pions and let them decay to muons;

2) You accelerate a second group of charged pions down your accelerator barrel, and let them "pick-up" oppositely charged muons along the way. This creates an exotic atom of "muonic pionium"; (either [/FONT][/FONT][/FONT][/FONT][/FONT][/FONT]π⁺ / μ^- or π^- / μ⁺, which when combined are electrically neutral (just like a hydrogen atom).

This "exotic atom" then becomes the weapon's beam. Note that both the muons and pions will be manipulatable via the Weak-Interaction (i.e. Nuclear Dampers and Meson Screens are both of use), and you solve the problem of how to accelerate a neutral particle in the wepaon barrel, as well as the problem of how to keep charged particles from mutually repelling once the beam has left the muzzle of the weapon.

Note also that whereas the π⁰ decays very quickly, both the charged pions and muons have a much longer half-life. Also, muons are one of the particles that penetrate very deeply into matter before being stopped.

Mesons in the game supposedly pass through armor mostly unhindered. I don't know if that's true or not - and it seems muons are pretty useful for that feature as well, wonder why they didn't use those - but would the exotic atoms you built likewise pass through, or are you getting an impact and then decay on or in the target's armor?

 

[whulorigan]

1/N means? Half life? Half decay in the indicated time, then half again, and so forth?

Isn't the point of the acceleration to bring the decay events to the desired location before the bulk of them decay? Am I to understand that most of the decay events are instantaneous?

Yes. It is an exponential decay. The relativistic velocity slows the decay rate, but half of the sample will have decayed by the first half-life increment (modified by time-dilation, of course). It's not that you could not have decays occurring within the target, it is just that many more decays will have occurred prior to hitting the target, and many of them will be close to the weapon's muzzle. I suppose it depends on just how fast you are theoretically accelerating them, whether the exponential decay curve between muzzle and target is steep or shallow. But either way the muzzle would need shielding.

Mesons in the game supposedly pass through armor mostly unhindered. I don't know if that's true or not - and it seems muons are pretty useful for that feature as well, wonder why they didn't use those - but would the exotic atoms you built likewise pass through, or are you getting an impact and then decay on or in the target's armor?

It is actually hard to find information about such properties, as most scientists when they write about particle-properties are not looking to put it to use for the things we are interested in for Traveller purposes. And, of course, it would depend upon the properties of the particular mesons being discussed. So far we have been exclusively talking about the three pi-mesons and muons (which are leptons, not mesons).

The problem with using muons directly is the same problem for any C-PAWS in vacuum: charged particles leaving a weapon muzzle repel each other and rapidly expand (no longer focused on a target point). That might not be as much of an issue for a meson-style weapon, but if they repel too far by the time they reach their target, you will no longer have a concentrated beam.

But even if the "exotic atom" as a unit has properties that would cause it to strike the hull, the resulting "ionization" of the exotic atom would strip the component particles from one another, allowing them to penetrate freely and decay.

 

[whulorigan]

The second way and my favorite answer involves Dr. Robert Meson (for whom the weapon is named), a researcher as part of the J3 effort discovers you can induce a jump field around a small region of space (say a few hundred pions or positrons), have the jump field accelerated out in a specific direction, only to have the field decay up to a minute or so later. Since the jump field isn't maintained properly, the results are a spray of the original particles, their decay products, and a host of virtual particles trapped when the jump field formed. The Meson screen is a field which causes the jump field for these little pockets to decay spontaneously. This technology later evolves into the Jump Projector and Jump Damper (as shown in the MT rules).

Another idea that had been suggested (again by MJD in one of his publications) is that "Meson Gun" was actually a top-secret code-name for the weapon when it was first created, that stuck. This is like how the first tank, the British Mark I in the 1st World War, was a top secret project. The industrial workers who built them were told that they were building "Water Tanks" for the soldiers on the Front, in order to keep the secret. But the code-name has stuck for almost 100 years, and we still call armored fighting vehicles "tanks" today. MJD suggested that perhaps "Meson Gun" was just a cover name (i.e. it's just another particle accelerator weapon . . .), but that its true operating principle actually has little or nothing to do with mesons (and the operating principles are simply left undefined).

That's the easy-way out explanation to get around the technical issues.

It might mesh nicely with your "Dr. Robert Meson" concept above.

 

[Carlobrand]

Okay, let's begin with the assumption that people are not making a weapon that blows up their own ship. By one or more of the methods suggested, they are arranging to have the bulk of the decay events occur inside a target anywhere from a few thousand klicks to a light-second away. Now the little puppies, traveling at some decent fraction of light speed, decay - or a lot of them do. A lotta gamma photons and some other interesting bits.

Gammas flying everywhere, random direction from the position of the "deceased" particle. The gammas heading away from the firing ship are blue shifted? The gammas heading back toward the ship are red-shifted? How far is that big shift going to drop them in wavelength? If I've imparted enough velocity to the original particle to substantially increase its life, are those photons headed back in the direction of the firing ship going to red-shift to visible light spectrum? The gammas flying at right angles are - now flying at 45 degrees from the forward line? How does the vector affect a photon emitted at a right angle to the line of travel?

 

[tjoneslo]

It might mesh nicely with your "Dr. Robert Meson" concept above.

The Dr. Robert Meson as the source of the name for the weapon isn't mine, it's been floating around the TML, and forwarded on to some other Traveller Forums, for several years. But it does make trying to explain the sufficiently advanced technology much simpler.

 

[tjoneslo]

Gammas flying everywhere, random direction from the position of the "deceased" particle. The gammas heading away from the firing ship are blue shifted? The gammas heading back toward the ship are red-shifted? How far is that big shift going to drop them in wavelength?

Both of these are correct. And the perceived wavelength changes depend entirely on the initial velocity of the particles.

If I've imparted enough velocity to the original particle to substantially increase its life, are those photons headed back in the direction of the firing ship going to red-shift to visible light spectrum?

Probably not. If you have a particle accelerator capable of imparting that kind of energy (velocity) onto a single particle, that becomes an impressive weapon on it's own. See xkck what if

The gammas flying at right angles are - now flying at 45 degrees from the forward line? How does the vector affect a photon emitted at a right angle to the line of travel?

This requires vector mathematics. Split the motion of the photon in to the forward (toward the ship) and lateral vectors. The forward vector contributes to the red/blue shifting of the photon, the other doesn't.

 

[Vladika]

Okay, let's begin with the assumption that people are not making a weapon that blows up their own ship. By one or more of the methods suggested, they are arranging to have the bulk of the decay events occur inside a target anywhere from a few thousand klicks to a light-second away. Now the little puppies, traveling at some decent fraction of light speed, decay - or a lot of them do. A lotta gamma photons and some other interesting bits.

Gammas flying everywhere, random direction from the position of the "deceased" particle. The gammas heading away from the firing ship are blue shifted? The gammas heading back toward the ship are red-shifted? How far is that big shift going to drop them in wavelength? If I've imparted enough velocity to the original particle to substantially increase its life, are those photons headed back in the direction of the firing ship going to red-shift to visible light spectrum? The gammas flying at right angles are - now flying at 45 degrees from the forward line? How does the vector affect a photon emitted at a right angle to the line of travel?

The decay will be the same regardless of the initial vector velocity. Thus, the decaying particles will have an initial direction and velocity of the original vector. Nothings going to "fly back at you".

 

[atpollard]

One question (in my mind) that I haven't seen addressed thus far in this conversation is:

What was wrong with the initial Traveller description that the weapon fires pairs of particles (whatever they are called) that converge inside the enemy ship and then decay (bell curved or exponential) occurs inside the target ship?

This may be a flawed concept, but I haven't seen the discussion that renders this model invalid. So I was curious and asked.



[I am not a particle physicist, nor do I play one on TV. ]

 

[whulorigan]

Okay, let's begin with the assumption that people are not making a weapon that blows up their own ship.

Well, it is a low-bid government contractor after all, but I'll concede.

Gammas flying everywhere, random direction from the position of the "deceased" particle. The gammas heading away from the firing ship are blue shifted? The gammas heading back toward the ship are red-shifted?

It is actually the other way around, presuming that the two ships are moving toward one another in the first place. The gammas coming back toward the firing ship would be blueshifted with respect to the firing ship, if the firing ship is moving toward the target, and only noticeably so if the ship is moving at a significant fraction of lightspeed toward the target. So I do not believe this will be an issue.

But conservation of linear momentum would likely mean that all of the decay products would more or less be moving along roughly the same vector (or at some angle to said vector) as the initially fired mesons/muons. So they should be scattering away from the firing ship in the general direction of fire.

How far is that big shift going to drop them in wavelength? If I've imparted enough velocity to the original particle to substantially increase its life, are those photons headed back in the direction of the firing ship going to red-shift to visible light spectrum?

As noted above, there should not be a big shift in wavelength in either direction. The decay of the mesons/muons will conserve all "conserved" quantities, such as energy, momentum (linear & angular), and some other more esoteric quantum-particle quantities as well. The total energy of all decay products (including the gamma photons) will be that of the total energy of the initial pre-decay particle(s).

The energy of any particle (photon or otherwise) is given by:

E=hf

where
E = Energy (in Joules),
h = Planck's constant (6.626x10^-34 Joule-Seconds)
f = Frequency (in Hertz).

(And wavelength λ = c/f,

where:
λ is in meters and
c = speed of light = 3.0x10⁸ m/sec)

​

and

E_total = m₀c² / (1 - v²/c²) ^1/2

where (for the mesons/muons):
E_total = Total energy of particle (rest + kinetic)
m₀ = rest mass of particle
v = velocity of particle
​

 

[whulorigan]

One question (in my mind) that I haven't seen addressed thus far in this conversation is:

What was wrong with the initial Traveller description that the weapon fires pairs of particles (whatever they are called) that converge inside the enemy ship and the decay (bell curved or exponential) occurs inside the target ship?

This may be a flawed concept, but I haven't seen the discussion that renders this model invalid. So I was curious and asked.

If I remember correctly, the idea was that the pairs of particles collided to create pi-neutral mesons (or pions & muons). I had always assumed that this occurred within the firing chamber mechanism, but maybe my mental concept has been wrong.

In your above example, relativistic time-dilation would not be necessary for timing purposes (as the particles are created at the convergence point either near or within the target), unless the particles composing the two converging beams were themselves unstable (which is a possibility).


EDIT:
According to High Guard (1980), p.18:

Meson Guns create high energy mesons and direct them at targets. Mesons have short lives, which can be prolonged to precise durations by accelerating them to relativistic speeds. If the point of decay is manipulated to occur inside the target ship, the result is high energy explosions and radiation damage. Because of the nature of the meson, it can pass through armor and matter without resistance.

Based on that statement, I have always presumed (as I think the rest of the posters here) that the mesons are created within the weapon firing chamber, and then projected at their target. Perhaps some other rules-reference is a little more specific, though.

In any event, the idea you suggested above creates a perhaps more workable weapon system. The technical hurdle would be how to intersect the two beams precisely at combat ranges in vacuum in order to create the mesons. Also, both particle beams would have to be electrically neutral particles, not only for the reasons above that I mention for any C-PAWS, but also because a simple electric or magnetic screen projected by a defending ship would cause beams of charged particles to misalign (even slightly), and they would then fail to intersect and create mesons/muons. Perhaps this is part of the operation of a Meson Screen, but it seems that even a much lower TL magnetic-device would then be a viable defense against a meson gun (for beams of charged particles rather than neutral, that is).

 

[Vladika]

...The technical hurdle would be how to intersect the two beams precisely at combat ranges in vacuum in order to create the mesons...

And this is the reason Meson weapons work best at higher TLs and larger (letter) types.

 

[Piper]

Meson accelerators were tested in the late 70's for cancer treatment.

They're as close to a Traveller meson gun as a bottle rocket is to a Saturn V but the principle is the same.

http://archive.is/78RW
__________________

 

[whulorigan]

Meson accelerators were tested in the late 70's for cancer treatment.

They're as close to a Traveller meson gun as a bottle rocket is to a Saturn V but the principle is the same.

http://archive.is/78RW

Fascinating. Thanks for sharing that.

 

[whulorigan]

If I remember correctly, the idea was that the pairs of particles collided to create pi-neutral mesons (or pions & muons). I had always assumed that this occurred within the firing chamber mechanism . . .

EDIT:
According to High Guard (1980), p.18:

[FONT=arial,helvetica]Meson Guns create high energy mesons and direct them at targets. Mesons have short lives, which can be prolonged to precise durations by accelerating them to relativistic speeds. If the point of decay is manipulated to occur inside the target ship, the result is high energy explosions and radiation damage. Because of the nature of the meson, it can pass through armor and matter without resistance. [/FONT]

Based on that statement, I have always presumed (as I think the rest of the posters here) that the mesons are created within the weapon firing chamber, and then projected at their target.

I just realized I never finished my thought on this.

Even if the weapon works according to the standard interpretation above (i.e. the mesons/muons are created withing the weapon firing chamber), the problem should be solvable by having a Weak-Nuclear Damper within the firing chamber and projecting out to a certain distance beyond the muzzle of the weapon, in order to stabilize & prevent premature meson/muon decay within or near the firing ship.

This can easily just be presumed to have always been a part of the standard Meson Gun design (unstated and "in the background", so to speak).

 

[Piper]

This stuff is way over my head, but perhaps this document from Fermilab might make sense to you:

http://lss.fnal.gov/conf/C711204/p.33.pdf


There's an accelerator schematic in the illustrations at the end of the document.

 

[darue]

I agree is has to be neutral charged mesons, probably neutral pions. but then how the heck are they accelerated? No way, the electromagnetic tricks wont work on them. so their speed is set at the point they're created. Two linear accelerators smash 'stuff' together, and the mesons fly out 'straight' while each of the linear accelerators are at some small angle off zero. Not sure what 'stuff' would be used, maybe protons in one and electrons in the other? maybe some heavier -1 charge particle.

A firing meson gun should have a visible "report" where the collision occurs, probably a hemispherical area dented into the ship, since not 100% of the source particles are going to collide perfectly and convert to neutral pions. So you'll get a very bright muzzle flash. it could actually happen a little distance from the ship. Also, not ALL the mesons are going to perfectly wait to decay, some will have a slightly wrong speed, so I think there would also be a slightly visible "ghostly" beam seen, though probably only briefly, dust would make it more visible.

The 'duration' of each shot virtually instantaneous or is the process able to sustain?

I do think each linear accelerator would have to be fed from a loop stage.

-

Nice to see the medical use of meson guns, I can imagine an old Imperial propaganda movie about the Pions for Peace Program. Watch us hollow out this asteroid in seconds!

 

[Piper]

See also JTAS #20, pp 40-41 and JTAS #13, p 8.