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Ron Moore | Fermilab | USA

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Shutdowns are Busy Times

Thursday, June 18th, 2009
Main Injector Lockout Box

Locks to prevent powering the Main Injector while people are working in the tunnel.

On Monday, we began a 3-month planned shutdown of the accelerators for maintenance, upgrades and a little construction for future operation.  Although we may not be delivering beam to the experiments, there is plenty of activity going on around the Fermilab accelerator complex.  The Accelerator Division “borrows” technicians from all over the lab to get all the work done.

For the Tevatron, maintenance is the biggest task.  It has been 20 months since the last long shutdown ended and many items have accumulated on the to-do list.  The biggest effort is to fix cryogenic leaks within the superconducting magnets.  When liquid helium leaks into the surrounding vacuum that helps insulate the cold part of the magnet, it creates an additional heat load that makes it harder to keep the magnet cold enough to stay superconducting.  We can usually add additional vacuum pumps to the magnet and overpower the leak so we can keep running until a planned shutdown.  However, sometimes a leak is big enough to cause us to shutdown immediately to fix it.  Fortunately, we have been able to survive with at least 6 leaks for many months, but now we are taking the time to fix them so we can run more reliably after the shutdown.

Tevatron dipole magnet interface

Tevatron dipole magnet interface

In order to fix such “cold leaks”, we must warm up part of the Tevatron to identify and replace the affected magnet.  The Tevatron is divided into 24 cryogenic “houses” whose plumbing for liquid nitrogen and liquid helium are isolated from the rest of the ring.  This scheme allows us to warm up only ~250 meters of the more than 6 kilometer circumference for such repairs.  If all goes well, it takes 9 days per house to warm up, find and fix the leak, verify there are no other leaks, and cool back down.  Occasionally, other problems develop during the thermal cycle, so it can take up to 2 weeks to make a house operational again.

Our mechanical support technicians make these jobs seem easy, but they put in lots of effort to do the job right and do it safely. For now we plan on warming up 6 houses to fix problems.   During this 3-month shutdown, they will spend most of their long working hours in the tunnel – coming up  every now and then for breaks, lunch, making sure replacement magnets are ready to be installed.  It’s good to see the sun from time to time.

Magnet alignment is another important shutdown task.  The Tevatron tunnel is not a static thing – the ground heaves and rolls a little bit over time and moves the tunnel and magnets with it.  We enlist help from the experimenters to measure the rolls of nearly 1000 magnets with neat little fixtures designed by my colleague Jim Volk.  They can complete the entire ring in about 1 week.  The 50 or so magnets with the largest deviations from  horizontal will be unrolled to within 1 milliradian.  That’s particularly important for the quadrupole magnets used to focus the beams.

Tevatron dipole magnet interface

Magnet mover lifting a B2 dipole bending magnet in the Tevatron.

Since I’m in charge of the Tevatron, I will make a tunnel tour on one of our carts at least once a week during the shutdown.  (It takes almost 30 minutes to go around the whole ring in a cart.  I want to post some video in a future post.)  I talk to the techs to see how things are going, look for any minor problems (broken fans, burned out lights, water leaks etc.), and just look at the machine.  It’s still one of the greatest engineering feats in the world.  Yesterday I was lucky enough to see an unused conventional (non-superconducting) magnet being removed to make room for a new device called a crystal collimator.  The big “magnet-mover” is impressive itself, even more so when it’s picking up a 24,000 pound magnet and hauling it down the tunnel.  You’ll never see me driving that thing with only inches to spare between the Tevatron on one side and the tunnel wall on the other.

While delivering luminosity to the CDF and D0 experiments is the reason we run the machines, we need the long shutdowns to fix what we can.  That may be especially important for this shutdown, since the Tevatron will likely end its run in 2011 and we will want to be as strong as we can for the last lap.

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Just a few links…

Thursday, June 11th, 2009

Here are a few links readers may find interesting…

I provide updates about the Tevatron on Facebook and Twitter – individual physics stores, weekly and monthly delivered luminosity to the experiments, and soon-to-be progress on the upcoming 3 month shutdown for maintenance. Click on the icons below…

In addition, the American Physical Society‘s Division of Physics of Beams (APS DPB) recently released a brochure about particle accelerators and their applications. You can find it here. Accelerators have many applications – not just for high energy physics.

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Making the Case in Washington, DC

Tuesday, June 9th, 2009
2009 users groups DC trip attendees

DC trip attendees

Every spring a group of high-energy physicists and graduate students trek to Washington, DC to visit the offices of Representatives and Senators to ask for their support in funding research in high-energy physics. As a member of the Fermilab Users’ Executive Committee (UEC), I made my first DC trip in April, along with members of the SLAC and US LHC users’ organizations. Over 40 of us made the trip and visited nearly 200 congressional offices over 2+ days. It’s a great opportunity to have our voices heard!

The DC trip takes quite a bit of organization to be successful. Planning starts several months in advance – when exactly to schedule the trip, who are the key people to visit, what will be our message. Who exactly do we meet? We certainly try to visit with the Members on appropriations committees since that’s where the budget is doled out, but they are only a fraction of our total. Of course, we schedule appointments with our own elected Representatives and Senators – we’re their constituents, so there’s a vested interest. But we also visit other offices where there is some other connection – where we grew up, where we went school, etc. In the end, we meet mainly with congressional staffers, not all of whom have a background or an interest in science, but communicating our message is still the point of the visit. Moreover, establishing and maintaining a relationship is key for making future contacts.

Crafting our message is vital, but it can vary quite a bit year-to-year. After particularly damaging cuts in 2008, our field benefited substantially from the ARRA “Stimulus Package” and the 2009 Omnibus budget bills. So, there were plenty of thank-yous to Congress, but also discussions of how we make a difference to society, directly or indirectly, through our research and education. (Take a look at our “1-pager” summary we brought to the meetings.) It’s also important is to remind the staffers how we get our funding – the Department of Energy (DOE) Office of Science funds the national laboratories, such as Fermilab, but the DOE and the National Science Foundation (NSF) both support university researcher grants. The America COMPETES Act aims to double federal support of the physical sciences by 2014, so we encourage consistent funding profiles to achieve that goal.

Ron and Congressman Bill Foster (IL-14)

Ron and Fermilab physicist-turned-Congressman Bill Foster (IL-14)

Overall, I found the trip to be very educational and positive. You may only have several minutes to get your message across to someone who may not share your point of view, or even be interested in it, so you need to expect different reactions. Two people from our group, one “primary” and one “secondary”, participate in each visit; the secondary jumps in if the conversation bogs down or to offer a different point of view. Finally, it was certainly interesting to walk up and down the hallways of the House and Senate office buildings between appointments and ponder the history that happened inside those walls. It was right there – government at work.

I am already looking forward to next year’s visit.

Contact your Members of Congress – they are there to serve you. Visit a web site such as congress.org to find out how to contact them.


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