Do H- annihilation spectra vary with element?

In summary, the conversation discusses the possibility of varying annihilation spectra with different elements during \bar{H} collisions, specifically at low temperatures. The concept of a "debris spectrum" is also introduced, but it is deemed not relevant due to the variability of outcomes in \bar{H} collisions with nuclei. The setup and design of an experiment to detect potential bias in the debris spectrum for different materials is also discussed.
  • #1
danR
352
4
Do [itex]\bar{H}[/itex] annihilation spectra vary with element?

If [itex]\bar{H}[/itex] collides (slowly, at 10 Kelvin for example) with H, Beryllium, Lead, does it make a difference?
 
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  • #2
I don't understand what you are talking about. The H- ion has no excited states, so it doesn't really have a spectrum.
 
  • #3
Vanadium 50 said:
I don't understand what you are talking about. The H- ion has no excited states, so it doesn't really have a spectrum.

I could have been less lazy and written antihydrogen, or [itex]\bar{H}[/itex].

For further clarification, annihilation-spectra refers not to ions, but matter-antimatter collision debris.

Can anyone else take a shot at it?
 
  • #4
An interesting possibility is that the antiproton briefly orbits the nucleus in place of an electron, forming what has been called an atomcule. See 'Antiprotonic Helium' article on Wikipedia.
 
  • #5
Bill_K said:
An interesting possibility is that the antiproton briefly orbits the nucleus in place of an electron, forming what has been called an atomcule. See 'Antiprotonic Helium' article on Wikipedia.

But what about the debris-spectra on annihilation? Does it vary with different materials? There's a reason behind this question pertaining to detection. If I coat the top and bottom of a chamber containing ant-H with different materials, each having a different spectrum of annihilation photons, then I don't have to 'image' and detect for both top and bottom collisions. Just examine the spectra.
 
  • #6
danR said:
I could have been less lazy and written antihydrogen, or [itex]\bar{H}[/itex].

could --> should. H- means something very different than an antiproton.

If I fire an antiproton into a nucleus 10 times, I'll get 10 different outcomes. Sometimes a few pions, sometimes many, sometimes mostly charged, sometimes mostly neutral. So the concept of a "debris spectrum" isn't really relevant.

There is a small effect based on the target Z. For large Z the nuclear electric field is stronger than for small Z, so pi+''s will be more energetic on average (because they are being repelled by the nucleus) and pi-'s will be less energetic on average (because they are being attracted by the nucleus).
 
  • #7
Vanadium 50 said:
could --> should. H- means something very different than an antiproton.

If I fire an antiproton into a nucleus 10 times, I'll get 10 different outcomes. Sometimes a few pions, sometimes many, sometimes mostly charged, sometimes mostly neutral. So the concept of a "debris spectrum" isn't really relevant.

There is a small effect based on the target Z. For large Z the nuclear electric field is stronger than for small Z, so pi+''s will be more energetic on average (because they are being repelled by the nucleus) and pi-'s will be less energetic on average (because they are being attracted by the nucleus).

Yes, my furtive substitution of modals entails a moral indiscretion. Soon I'll be making spelling errors. William Safire will weigh in.

By 'collision' I should clarify this is at or below 10 Kelvin (to keep them slow, the slower the better).

Here is a lengthy description of my setup:

I have a small (evacuated) chamber with beryllium and the bottom and lead at the top. (I don't really have this, and my university probably wouldn't let me near their shop; I'm lying through my teeth). antihydrogen atoms (not protons) are introduced.

They are not fired (which suggests quite some velocity; I should have avoided the term collided), better to say: come in contact with either the top or bottom. The positron/antiproton interacts with either a high-mass atom (surface-lattice, to be precise) at the top, or with a low mass atom at the bottom.

From what you say about proton-antiproton differences, is it reasonable to think there will be a statistical difference in the distribution of debris-species spectra with respect to antihydrogen proper?

If I run my experiment long enough, I will see whether anti-H falls or rises without having to train separate detectors on the bottom and top of the vessel. Naturally, the thing must be shielded from stray radiation, confounding fields, and the like.

Over a long run I'm thinking there should/could be peaks in the spectrum of debris showing a bias for top or bottom.
 
  • #8
danR said:
Yes, my furtive substitution of modals entails a moral indiscretion. Soon I'll be making spelling errors. William Safire will weigh in.

Son, if this is how you react to being shown you made an error, your career in science will be very short indeed.

Your setup needs some way of measuring the energy or momenta of the particles produced. If you can do that, you might as well measure the direction of the anti-atom directly. What your apparatus does is takes a big effect: "up" or "down" and turns it into a small one - subtle differences in pion spectra. You want to go in the other direction.
 

Related to Do H- annihilation spectra vary with element?

1. Do H- annihilation spectra vary with element?

Yes, H- annihilation spectra can vary with element. The spectra are influenced by the atomic structure and energy levels of the element, which can differ depending on the number of protons and electrons present. This can lead to variations in the energy and intensity of the annihilation peaks.

2. How do you measure H- annihilation spectra?

H- annihilation spectra can be measured using techniques such as positron annihilation spectroscopy or gamma-ray spectroscopy. These methods involve detecting the gamma rays produced during the annihilation process and analyzing their energy and intensity to determine the spectra.

3. Can H- annihilation spectra be used for element identification?

Yes, H- annihilation spectra can be used for element identification. Each element has a unique spectrum, making it possible to identify the elements present in a sample by comparing the measured spectra to a database of known spectra.

4. How do impurities affect H- annihilation spectra?

Impurities in a sample can affect H- annihilation spectra by altering the atomic structure and energy levels of the elements present. This can lead to changes in the shape and intensity of the annihilation peaks, making it important to account for impurities when analyzing spectra.

5. Can H- annihilation spectra be used to study chemical bonds?

Yes, H- annihilation spectra can provide information about chemical bonds. The energy and intensity of the annihilation peaks can be influenced by the type and strength of chemical bonds present in a sample, allowing for the study of molecular structures and bonding interactions.

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