DNP2007

It's been a few weeks since the 2007 DNP meeting - the annual get together of the American nuclear physicists (DNP=Division of Nuclear Physics) - took place, but I think I'm still on time for this not-so-short review. Here it is, dedicated to all of you who had to stay at the lab babysitting 84Mo and such exotic isotopes.

After attending a few meetings and conferences I've discovered that many times the major thing going on, listening to and presenting scientific work, is not necessarily the most important thing you take back home. There are many other interesting side effects. A nice one is simply the possibility to visit some distant place. Physicists tend to be a hard working bunch, and they require a little incentive to venture out of their lab. The meeting location could also serve as an extra attraction for those meetings which are not so well established, which don't have a big reputation. Who could resist going to a paradisiacal island in the Aegean sea if all you have to do is sleep through a few talks with slides filled with obscure equations!

The DNP is a big meeting in nuclear physics, so it can afford being held pretty much anywhere - they even had one in East Lansing! This year it was in a place named Newport News, VA. It was the first time I had heard the name. I did just enough googling before the trip to know it was not far from Jamestown, VA - regarded as the first European settlement in the this great country - neither from the Atlantic ocean (I packed some shorts!), and that the conference was in a place called "Oyster Point at City Center". I knew I wouldn't have much free time, but I would have welcomed some history lessons about colonial eras, or the chance to be rolled around by salty waves - no offence Lake Michigan, but the ocean is one of the things I miss the most from Uruguay.

What i found? A shopping mall! Someone decided to transform a pice of swamp in Virginia into a freaking shoping mall that you can live on, complete with its pond with fountains and ducks, and organic shops selling sweet potato pie, and fancy hairdressers. It also included a hotel where the conference took place. Zero local flavour. On top of that, the it was surrounded by wide avenues with the usual assortment of made-in-China department stores and chain eateries. The only way to tell it was Virginia and not any of the other 49 states was by the license plates in the cars! Not everything was grim though. The conference hotel offered 'upscale comfort'. Also, since the residences for the shopping mall dwellers were still under construction, us physicists attending the DNP were almost the only ones roaming the pristine sidewalks (no chewing gum to get stuck on your shoe), and everywhere you'd go for a coffee or a piece of sweet potato pie you'd find some other physicist to chat and catch up with the latest news, or recollect the legendary anecdotes of the field - and this social interaction is also a very important side effect of any physics meeting.

The most 'touristy' thing I did was a visit to JLab & their science at the frontier between nuclear and high energy physics. They spiced up the experience by stressing several times we'd be going through confined spaces several meters underground. In our first stop we had to descend 4 flights of stairs into the accelerator tunnel. A line marked the phreatic sheet: we were not only at risk of suffocating by lack of oxygen, but we could drown if one of the walls decided to crack! At the tunnel there were several physicist and engineers waiting for us at different points along the accelerator - their reddish eyes already showing the strain of trying to explain nuclear physics to a continuous stream of visitors in a noisy experimental vault, but they were still enthusiastic and eager to show their work. At least we were all physicist - not like the time the NSCL had the brilliant idea of hosting an open house to celebrate the International Year of Physics (2005). It turned out to be a rainy day and a few activities around campus (e.g. a dog show) got cancelled, so we ended up swarmed by quite a diverse crowd... In any case, the JLab staff proudly showed us their tiny magnets to steer electrons and the helium cooling system, until we emerged to the light at the other end of the tunnel.

Then things got a little confusing. Another scientist, without giving us much explanation, pointed to two large tunnels opening on the ground and descending to what looked like huge caves. "Experimental hall A or C, you choose, proceed on your own". It felt Alice in Wonderlandishy: "choose the red or the green pill" (is it a pill? i have to read that book sometime). I could only imagine a fierce dragon sleeping in one cave, and a grad student eager to explain a poster filled with generalized parton distribution function equations in the other. I chose Hall C. I found a cylindrical room full of large magnets and detectors, all painted in different bright colors. They seemed to be placed at completely random order - it was the first experimental vault I've been to where I had to ask someone in what direction the beam was coming from. Not a dragon's nest, but a gigantic toddler's playing room. In hall A I avoided the grad student with his poster and just contemplated their version of the NSCL's S800 spectrograph - they had the S800's twins big brothers (called BigBite!) a spectrometer for electron scattering. A graphic demonstration that the smaller the particle you want to study, the larger the machine you need. We got a JLab coffee mug.

A lot of the meeting was about nuclear astrophysics - but that might have just been my biased selection of talks. My 'personal favourite' was the session on "New Nucleosynthesis Processes" (here), where some of the new & upcoming stars of the field showed their latest work. Our own Fernando Montes, and Carla Froehlich (U.Chicago) discussed some processes that might fill a few gaps left by the good old B2FH - that's a famous paper by Burbidge, Burbidge, Fowler and Hoyle (I should also throw in Cameron to be politically correct & hitorically accurate) who 50 years ago came up with the basic ideas of how a few nuclear processes are enough to explain how a star can be born with just a few ingredients and by the end of its life cooked up a soup with most of the elements in the periodic table. However, some recent astronomical observations tell us B2FH+C might not be the whole story - sometimes it's really fascinating the things astronomers can tell us about the stars; for example, it's relatively much easier to say how many atoms of each element you have in a star than whether it has any planet going around it. Montes and Froehlich said the LEPP (Light Enchilada Pikante Process) and the neutrino p-process might have some words on the solution of this new question. Nevine Weinberg theorized about the possibility of neutron stars being messy eaters (mass ejection from X-ray bursts in accreting neutron stars), and finally Bildsten - a 'old star' of the field - proposed a new type of exploding star: type .Ia supernova - the '.' in not a typo! It's some kind of thermonuclear explosion that - as I understood it - is barely strong enough to explode and eject some radioactive nuclei, and that we could mistake for a type Ia supernova if we're not careful. It'll be interesting to see how all these ideas evolve.

Once i ventured into a nuclear structure session when there was a talk on hypernuclei. I understood half of the first slide - the top half, which had the speakers' name and the title of the talk. The other half already had some numbers for measurements (or predictions, i couldn't tell fact from fiction) of resonance energy and half lives, or so. Not that it was a frantic 10 minute talk and the speaker was trying to cram as much information per slide as possible, it was a 30 minutes long invited talk! The next 2 slides were some spectra with a delta resonance that I recognized from the nuclear structure class from last year (at least I knew there is such a thing as a delta resonance. it's like a 'pumped up' version of a neutron or proton that is a little bit more heavy than the regular type, and if you stick one of them into a nuclei it becomes an 'hypernuclei'). Yet, 2 or 3 minutes afterwards the speaker had alreday gone through 459 more numbers (all in units of MeV or pico seconds) and I was completely lost again. I guess i'm on the way to become a great nuclear physicist - you can't expect less from the NSCL ;) - but I'm not 'hyper' yet.

The Low Energy User's Meeting was another interesting one - it attains us all ere at the lab. It squared off the different US laboratories that do research in similar areas of nuclear physics as we do at the NSCL, and each had an short time to present their latest projects and whine about the perils of working within the current federal budget constrains. I'm still exploring the editorial criteria for this blog, so I won't say much other than the NSCL - on the hands of Prof. Thoennessen - gave a rock solid performance: "We're moving forward with stopping and reaccelerating beams up to 3MeV.... for real, you'd better believe me". I'm not sure what kind of skeptics he was addressing - with our cyclotron that accelerate nuclei to about half of the speed of light we produce some of the fastest moving nuclei you'd find on earth, and making them into a beam of 3MeV would be like slowing down a F1 race car to the pace of my grandma walking in the park, and it doesn't seem to make much sense (but yes, there are several reasons why we need it - that's for another blog); but I think the skepticism comes because it's in a physicist nature to be skeptics, and also to do difficult things (and stopping and reaccelerating crazy fast nuclei is one of them), so there'll always be someone that is not convinced we can do it until the new machine is working (the project here). There was also a report on the highlitghts from the VI Exotic Beams Summer School that took place at the lab during the summer: the students measured the half life of phosphorous 35, they had a dinner cruise in the Grand River, and in the NSCL coffee room we still have a box with free vegetable leftovers from the farewell reception for anyone to take (I think someone put it on the fridge by now).

My presentations went ok. I didn't get any qestions, just nice comments. The first talk was during a special session to celebrate 10 years of the Conference Experience for Undergraduates (CEU) program [go CEU! have you noticed most of us bloggers did some undergraduate research?]. The audience was composed mostly of yawning undergrads. I only spotted a couple of them napping in the comfortable chairs, so i guess i caught their attention by maximizing neutron stars and minimizing equations - there was only E=mc2 and one equation to explain how you can tell how heavy a nucleus is by watching it speed through the set of pipes and magnets we like to call 'the beamline' - that's basically my thesis project, measuring the mass of some exotic isotopes. At the end someone asked me if I was italian. So for the next talk, in which i was substituting for Giuseppe Lorusso who couldn't make it to the meeting, I began by letting everyone know my accent was Spanish and not Italian. By the way, Giuseppe is my officemate, roommate, & academic sibling (I recently learned there's such a thing as an academic genealogy tree)....wait... actually I think we've never been seen at the office simultaneously... and when I'm feeling a little lazy and postpone doing the dishes they just pile up for days and nobody ever seems to care about them. Maybe it's just all in my mind and we're one and the same person, Giuseppe being my alter ego for the times I want to dress up in Italian glamour....oh! .. this is going nowhere .... I'd rate that second talk about our neutron detector named after a Roman emperor (NERO) with 3.5 main sequence stars, the same overall rating I'd give to the rest of the DNP meeting.