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Sitting down to LJ for the first time in the past week. Goodness, it has been a busy time!
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resourceress arrived in Oxford last Wednesday for a month-long stay. We ate lunch at the Noodle Bar and got her settled in, then I went back to work at the University for a bit. Got together later in the evening for a long walk around the city, past many of the Oxford highlights like the Carfax Tower, the University Church of St. Mary the Virgin, the Magdalen Bridge, the Bodleian Library, the Sheldonian Theatre, and the Radcliffe Camera. On the way, I found several more post boxes that I need to go back and photograph later. Also during the walk, we stopped in Cowley to eat dinner at an Indian restaurant.
On Thursday, bothresourceress and I worked. We met at mid-day for lunch at the Eagle & Child pub, eating in the Rabbit Room, where C.S. Lewis, J.R.R. Tolkein and others (the "inklings") used to meet each week.
On Friday, we left Oxford and started our road trip. We began by going to Avebury, where we saw the standing stones in the circle, and admired some of the town (e.g. the old dovecote). We also saw nearby sites of interest, like Silbury Hill (an artificial hill about 4500 years old) and the West Kennet Long Barrow (a large mass grave from about 5500 years ago). Then it was back in the car and off to Stonehenge. Stonehenge needs no further commentary. Once done there, we drove to Salisbury to see the cathedral there. Quite an impressive sight, containing the oldest functioning mechanical clock in the world (from the 1300s). The cathedral also contains one of the four surviving original copies of the Magna Carta, from 1215. The one at Salisbury is said to be in the best condition, though I won't know until I see the other three. After eating dinner at a pub in Salisbury, we drove to Glastonbury and checked into the Backpackers hostel there.
Saturday was spent at Glastonbury. We went to the ruins of the Abbey, destroyed in the 16th century after Henry VIII dissolved all the monasteries. I chatted a "monk" (tour guide) from Binghamton, New York, that I had first met back in May. After exploring the grounds of the Abbey,resourceress and I got lunch, then spent some time in the town. They are Pagan shops galore; quote resouceress: "It's just like Salem, only more so." So we spent a couple of hours making our way through them. We also visited the Goddess Temple near the center of town. Then it was off to the Chalice Well gardens and spring, where we spent a couple of hours before climbing the Glastonbury Tor. Unlike May, when I climbed the side that has a gentle gradient, we went up the path on the steep opposite side. There was a large crowd at the top, but we were able to take some good pictures, nonetheless. Then we headed down the more gentle slope and back into town for dinner and dessert at an Italian restaurant.
Sunday we ate a traditional English breakfast (vegetarian style, of course!) before leaving Glastonbury and driving to nearby Wells. In Wells, we walked down the Vicars Close, which claims to be the oldest planned road in Europe. We also visited the Wells Cathedral, which is quite impressive for a relatively small cathedral. The outside stonework is very ornate. Inside, there is a very elaborate clock that chimes the quarter hours with kicking hands & feet, as well as jousting knights. When done at the cathedral, we looked in on the Bishop's Palace and walked around part of the moat. However, in the interests of time, we did not go inside... but instead hopped back in the car and went on to Bath. In Bath, we started out by getting lost once we left the car in the car park. With a little help, we finally made our way to the Bath Abbey and toured the inside. Although the Roman Baths are directly next to the Abbey, they are open later than any other attraction in town, so we walked North (and up) to the Museum of Bath at Work, which documents the history of labour and industry in Bath and the surrounding area. Then we visited the Museum of Costume and the Assembly Rooms, which had exhibits on fashion. Their oldest piece was a dress worn in the court of Charles II, back in 1660. After the Museum of Costume closed, we got dinner at a vegetarian pub and took a scenic walk around town, passing over the Pulteney Bridge (which is lined with shops) and walking along the river banks. It was a perfect summer evening, with temperate evening air as we walked by the water past old medieval architecture... while the music from an outdoor summer concert filled the air. Finally, around 8pm, we arrived back at the Roman Baths and spent the next two hours at the old bath houses, which also used to be a shrine to Sulis Minerva. You can drink a sample of the water from the spring, which we did... but -- goodness -- does it taste awful! When done at the baths and shrine, we drove back home to Oxford.
Yesterday, Monday, I went to work and started closing up the K-400 cryostat for another attempt at cooling it down to base temperature. I still need to write an entry about why I want to do this, I know. On my lunch break, I signed the lease for my new flat and then, at 5pm, I left work early (a short day meaning nine to five) to move out of the room that I was renting and into my new flat. With some help fromresourceress, the whole move only took a couple of hours. One of the easiest moves of my life. So I now have my own place to live here in Oxford! Excellent! And only an eighteen minute walk from work, too... (With my commute going down once I start cycling instead of walking) The price for this two bedroom flat is ridiculously high -- much more than the mortgage on the Event Horizon -- but for Oxford, the price is actually pretty good. I am quite excited about my new place, and I cannot wait for cheshcat and our kitties to arrive next month! Anyone who wants my new contact information, the address and the phone number of the landline, should e-mail me.
Today, Tuesday, has been another work day. I took a long lunch break -- three and a half hours -- to meet up withresourceress to buy essentials (e.g., dishes, pots, utensils, water filter) for the new flat. Then back to work, where the K-400 is partially closed and I am now pumping out the inner vacuum chamber.
And that, gentle readers, is the excitement of the past week...
resourceress arrived in Oxford last Wednesday for a month-long stay. We ate lunch at the Noodle Bar and got her settled in, then I went back to work at the University for a bit. Got together later in the evening for a long walk around the city, past many of the Oxford highlights like the Carfax Tower, the University Church of St. Mary the Virgin, the Magdalen Bridge, the Bodleian Library, the Sheldonian Theatre, and the Radcliffe Camera. On the way, I found several more post boxes that I need to go back and photograph later. Also during the walk, we stopped in Cowley to eat dinner at an Indian restaurant.On Thursday, both
resourceress and I worked. We met at mid-day for lunch at the Eagle & Child pub, eating in the Rabbit Room, where C.S. Lewis, J.R.R. Tolkein and others (the "inklings") used to meet each week.On Friday, we left Oxford and started our road trip. We began by going to Avebury, where we saw the standing stones in the circle, and admired some of the town (e.g. the old dovecote). We also saw nearby sites of interest, like Silbury Hill (an artificial hill about 4500 years old) and the West Kennet Long Barrow (a large mass grave from about 5500 years ago). Then it was back in the car and off to Stonehenge. Stonehenge needs no further commentary. Once done there, we drove to Salisbury to see the cathedral there. Quite an impressive sight, containing the oldest functioning mechanical clock in the world (from the 1300s). The cathedral also contains one of the four surviving original copies of the Magna Carta, from 1215. The one at Salisbury is said to be in the best condition, though I won't know until I see the other three. After eating dinner at a pub in Salisbury, we drove to Glastonbury and checked into the Backpackers hostel there.
Saturday was spent at Glastonbury. We went to the ruins of the Abbey, destroyed in the 16th century after Henry VIII dissolved all the monasteries. I chatted a "monk" (tour guide) from Binghamton, New York, that I had first met back in May. After exploring the grounds of the Abbey,
resourceress and I got lunch, then spent some time in the town. They are Pagan shops galore; quote resouceress: "It's just like Salem, only more so." So we spent a couple of hours making our way through them. We also visited the Goddess Temple near the center of town. Then it was off to the Chalice Well gardens and spring, where we spent a couple of hours before climbing the Glastonbury Tor. Unlike May, when I climbed the side that has a gentle gradient, we went up the path on the steep opposite side. There was a large crowd at the top, but we were able to take some good pictures, nonetheless. Then we headed down the more gentle slope and back into town for dinner and dessert at an Italian restaurant.Sunday we ate a traditional English breakfast (vegetarian style, of course!) before leaving Glastonbury and driving to nearby Wells. In Wells, we walked down the Vicars Close, which claims to be the oldest planned road in Europe. We also visited the Wells Cathedral, which is quite impressive for a relatively small cathedral. The outside stonework is very ornate. Inside, there is a very elaborate clock that chimes the quarter hours with kicking hands & feet, as well as jousting knights. When done at the cathedral, we looked in on the Bishop's Palace and walked around part of the moat. However, in the interests of time, we did not go inside... but instead hopped back in the car and went on to Bath. In Bath, we started out by getting lost once we left the car in the car park. With a little help, we finally made our way to the Bath Abbey and toured the inside. Although the Roman Baths are directly next to the Abbey, they are open later than any other attraction in town, so we walked North (and up) to the Museum of Bath at Work, which documents the history of labour and industry in Bath and the surrounding area. Then we visited the Museum of Costume and the Assembly Rooms, which had exhibits on fashion. Their oldest piece was a dress worn in the court of Charles II, back in 1660. After the Museum of Costume closed, we got dinner at a vegetarian pub and took a scenic walk around town, passing over the Pulteney Bridge (which is lined with shops) and walking along the river banks. It was a perfect summer evening, with temperate evening air as we walked by the water past old medieval architecture... while the music from an outdoor summer concert filled the air. Finally, around 8pm, we arrived back at the Roman Baths and spent the next two hours at the old bath houses, which also used to be a shrine to Sulis Minerva. You can drink a sample of the water from the spring, which we did... but -- goodness -- does it taste awful! When done at the baths and shrine, we drove back home to Oxford.
Yesterday, Monday, I went to work and started closing up the K-400 cryostat for another attempt at cooling it down to base temperature. I still need to write an entry about why I want to do this, I know. On my lunch break, I signed the lease for my new flat and then, at 5pm, I left work early (a short day meaning nine to five) to move out of the room that I was renting and into my new flat. With some help from
resourceress, the whole move only took a couple of hours. One of the easiest moves of my life. So I now have my own place to live here in Oxford! Excellent! And only an eighteen minute walk from work, too... (With my commute going down once I start cycling instead of walking) The price for this two bedroom flat is ridiculously high -- much more than the mortgage on the Event Horizon -- but for Oxford, the price is actually pretty good. I am quite excited about my new place, and I cannot wait for cheshcat and our kitties to arrive next month! Anyone who wants my new contact information, the address and the phone number of the landline, should e-mail me.Today, Tuesday, has been another work day. I took a long lunch break -- three and a half hours -- to meet up with
resourceress to buy essentials (e.g., dishes, pots, utensils, water filter) for the new flat. Then back to work, where the K-400 is partially closed and I am now pumping out the inner vacuum chamber. And that, gentle readers, is the excitement of the past week...
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From:
no subject
Congrats on finding a home there.
From:
no subject
It's a good question!
Assuming everything works correctly -- which is almost certainly not the case -- here is the procedure and time estimates for going from an open cryostat at room temperature to a fully cooled cryostat at base temperature:
Day One
=======
Inspect all the wiring and connections on the equipment (1/3 day)
Make an indium seal and close the inner vacuum chamber (1/2 day)
Start pumping out the inner vacuum chamber (rest of day, plus leave running overnight)
[Note: This week, it took me two days (Mon/Tue) to complete the "Day One" tasks]
Day Two
=======
Leak test the inner vaccum chamber, which should now be evacuated to a good vacuum [0.0001 millibars] (1/5 day)
Close the main bath to seal the cryostat (1/2 day)
Pre-cool with liquid nitrogen (1/3 day)
Let sit overnight with liquid nitrogen
Day Three
=========
Pump out liquid nitrogen (1/4 day)
Flush with helium gas to remove residual nitrogen gas (1/8 day)
Fill with liquid helium (1/2 day)
Let sit overnight with liquid helium
Day Four
========
Pump the 1K pot, start circulating the helium-3/helium-4 mixture, et cetera (1/2 day)
At the end of this, if all has gone well, you should reach 5 millikelvin about halfway through the fourth day. At which point you can begin making the low temperature measurements...
Of course, to date, I have not successfully cooled down a cryostat below 400 millikelvin. In fact, our youngest grad student has been here for a year and he says that -- out of the three cryostats here in our lab at Oxford -- there has not been a cryostat cooled down to base temperature while he has been here. It's tough stuff!
Right now, three days into the week, I am stuck halfway down the list of the "Day Two" tasks. We closed the main bath, but there is a gap which has a leak. Not good. After spending a couple of hours on this, we decided to give up until tomorrow morning...
Am I right in assuming that each step closer to 5mK takes progressively longer?
Not really, actually. Once you have the liquid helium in, cooling it all down to 4K, the last steps should come pretty quickly. The more time consuming parts happen at room temperature, getting all the seals closed up properly and leak tested and whatnot. It isn't a bad assumption, mind you, but it doesn't apply here.
And, of course, in practice, the task of troubleshooting all the problems that pop up is really what takes so much gosh darn time! :)