Congratulations Dr. T. Desell to a job very well done. An impressive slide show and very nice that Milky Way was a part of your PhD.
This is a milestone in your scientific career and I wish you all the best on your way through science wherever you go.

Good luck also with the hard disks and servers in the coming weeks doctor Trais.

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Greetings from,
TJ

Second the congratulations! Welcome to the club! I know you have a postdoc through next summer...then the real challenge begins. I bailed and went corporate. Good luck Travis!

Thanks everyone ;) I'm hoping I get lucky with a professorship somewhere :)

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Congratulations Travis!

You first had the defense and then finished your thesis? I have to do it the other way around ;)

I submitted my thesis earlier today and will defend it in 5 weeks if all goes well. At least that's the plan, the referees have to be fast enough with their reports.

I submitted my thesis earlier today and will defend it in 5 weeks if all goes well ...

Looks like we'll all be saying, "Congratulations, Dr CP ..." as well :-).

What is your field of research and what is the title of your thesis?

What do you plan to do when all formalities are completed? Enter Academia like Travis or bail like Martin? :-)

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Cheers,
Gary.

I submitted my thesis earlier today and will defend it in 5 weeks if all goes well ...

Looks like we'll all be saying, "Congratulations, Dr CP ..." as well :-).

After my defense the faculty council has to decide about my thesis (especially about the grade the examining committee suggests to them ;). After that I will receive a letter about the result. Only then I'm allowed to call myself a doctor rerum naturalium (doctor of natural sciences), before that it would be a crime here ;)

What is your field of research and what is the title of your thesis?

Guess I've mentioned it before that my field is cluster physics ;). The title of the thesis (actually written in German) is "Dynamics of metal clusters in superfluid helium droplets".
What I do is to produce very small helium droplets (smaller than a micron, temperature only 0.37K, they are superfluid!) flying with some 150 mph through a vacuum. When those droplets pass a very low density metal vapour (or any other gas), they pick up atoms from the vapour and clusters are formed inside the droplets (at least for most materials).
After that I shoot with different lasers on the thing and see what happens ;)
The lasers range from low intensity versions with different (tunable) wavelengths to do some spectroscopy up to quite high power short pulse lasers to (simply put) blow everything up. High power means here several PetaWatt/cm², for others this is still a moderate intensity, but clusters absorb very efficiently ;)

I've also participated in some experiment campaigns (quite an effort and a lot of people involved) on the VUV-FEL (vacuum ultraviolet free electron laser, has now the fancy name "FLASH" :]) in Hamburg trying to determine the properties of a special type of plasma created from micron sized cryogenic hydrogen pellets. Actually we worked (beside others) with some people from the NIF (National Ignition Facility, Lawrence Livermore National Lab, they try to get fusion by shooting with some 192 HUGE lasers into a small tube with a tiny deuterium/tritium target, they have a nice video on the linked page) for that experiment. I built the source for the hydrogen pellets (some tens of microns diameter, it was even working sometimes ;) used at the FEL. But that didn't fit the topic of my thesis, so I didn't write about it.

What do you plan to do when all formalities are completed? Enter Academia like Travis or bail like Martin? :-)

That is an open question. My currrent fixed term contract still runs a few months. Probably I will look for a PostDoc position somewhere. The economy doesn't look that bright right now, but an interesting job in a R&D department somewhere is nothing I would turn down ;). Just as examples, two former colleages went to Philips, another one to AMTC in Dresden (Advanced Mask Technology Center, right next to AMD^H^H^H GlobalFoundries' Fabs there). And there is one now at the NIF (took almost a year for all the security checks before he was allowed to ink his contract ;).

Thank you very much for your detailed response. I'm sorry if I got you to repeat stuff but I don't think I'd seen all that anywhere else before. That's probably not too surprising as sometimes the bleeding obvious does escape me :-). For instance I hadn't twigged to the identity of one of the authors of the ppam paper until very recently!

Anyway, I'd just like to wish you all the very best for the productive career that obviously lies before you. And Travis too, of course (to bring the thread somewhat back on topic) :-).

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Cheers,
Gary.

And there is one now at the NIF (took almost a year for all the security checks before he was allowed to ink his contract ;).

That's not surprising. Los Alamos does do an interesting mix of physics research with international collaborators (such as on NIF) along with super-secret nuclear weapons research (some NIF data feeds that as well, at least according to open sources). Does cause a bit of institutional schizophrenia. For a foreign national to get direct exposure to that environment must take a fair amount of background checking. The Department of Energy has a separate clearance process from the Department of Defense, but where we work people do have to wait many months to get some of the higher level accesses processed. I've had a clearance for nearly 20 years, so it's old hat to me by now. A bit of a culture shock to a recent academic though.

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Better is the enemy of the good. -Voltaire
Never ascribe to malice that which is adequately explained by incompetence. - Napoleon

Yes, Congratulations to Dr. Travis Desell!

I couldn't help but notice:

What I do is to produce very small helium droplets (smaller than a micron, temperature only 0.37K, they are superfluid!) flying with some 150 mph through a vacuum.

I did a lot of materials research before switching to astrophysics, and I was curious about a few things. Do you use helium-3 or helium-4? I am guessing helium-4, it has a higher superfluid temperature, but in any case, superfluids have exciting quantum mechanical properties; how to you keep the droplets from being destroyed so that you can analyze them? Or is the analysis done while the drop is still moving? Which metals do you use, and are they in a magneto-optical trap (MOT)?

I should just read the publications, lol. Could you link me to them, please? Thanks a bunch!

I couldn't help but notice:

What I do is to produce very small helium droplets (smaller than a micron, temperature only 0.37K, they are superfluid!) flying with some 150 mph through a vacuum.

I did a lot of materials research before switching to astrophysics, and I was curious about a few things. Do you use helium-3 or helium-4? I am guessing helium-4, it has a higher superfluid temperature, but in any case, superfluids have exciting quantum mechanical properties; how to you keep the droplets from being destroyed so that you can analyze them? Or is the analysis done while the drop is still moving?

Yes, helium-4. One would need much lower temperatures to get helium-3 superfluid. Sometimes one uses helium-3 to compare with a normal fluid and to see what the superfluidity actually adds to a certain effect. But as helium-3 is really expensive, this is done only for quite limited experiments.

But the helium droplets are primary a tool for me. The focus is actually on the atoms, molecules and clusters I put in those droplets. The quantum nature of the helium surrounding has sometimes interesting effects on the embedded particles.
And yes, it is basically a molecular beam experiment, so one does the measurements on the moving droplets. By the way, I just see that I confused a bit my conversion to mph of the speed figure I gave for the droplets (I'm more accustomed to metric units ;). They are actually moving with a speed of roughly 500 to 550 mph.

Which metals do you use, and are they in a magneto-optical trap (MOT)?

I used mainly silver and magnesium (but did experiments with copper, gold, and cadmium, too). But it doesn't even need to be metals. Quite a lot of the experiments with the high power femtosecond lasers are done with the rare gas Xenon.
As we just want the doping material to be picked up by the droplets, there would be no sense in using a MOT. For gases you just let it into a vacuum chamber the droplets pass (in a controlled way and very tiny amounts of course). For solid materials you normally heat them simply in an oven to evaporate them, a very low vapour pressure (10^-5 to 10^-4 mbar, 1.0 torr = 0.76 mbar) is enough. Most materials don't even melt at the needed temperatures, they sublimate enough atoms below their melting point.

I should just read the publications, lol. Could you link me to them, please? Thanks a bunch!

Just search for me on ISI Web of Knowledge ;). Your insitute should have access.

But to directly link a few:

One of the last papers I was involved in (already accepted by Physical Review A, but not published yet) deals with the optimization of femtosecond laser pulses to control the coulomb explosion of clusters. We also used a genetic algorithm, not to fit some streams to the observed stars of the milkyway, but to get the optimal laser pulse shape ;)

Another one shows that several Mg atoms in a single helium droplet exhibit a peculiar behaviour, which is linked to the very low temperature and the formation of a special structure under those circumstances.

The low temperature is again the reason, why we were able to measure some electronic states of silver dimers here, which are not stable at the higher temperatures in "normal" experiments.

Thanks a bunch, CP! I now have some weekend reading... :)