Cryostat Integration

I meant to update this a few days ago, but haven’t had a chance yet. It’s been an exciting week: we got the cryostat on the gondola and we have an almost fully built instrument!


Carolyn was really excited about the arrival of the stycast. It was shipped in this container of what looked like gold chunks, which was a little weird.

Getting the cryostat on the gondola was a bit of a challenge. The crane inside the hangar is too low relative to the gondola to lift the cryostat on top of the gondola. To get around this, we thought we could lift the gondola off the cart, lift the cryostat onto the gondola, and then put the gondola back on the cart. Unfortunately, the crane is too low to even lift the gondola while inside. We ended up rolling the gondola outside and using a different crane that’s out there.


The riggers trying to lift the gondola off the cart using the inside crane. I think this was their third and last attempt.


Because we were working outside on the runway / helicopter launch area, we had to wear bright colored vests (and hard hats are always necessary for lifting operations). McBride’s hard hat wouldn’t stay on, so he made a chin strap out of balloon tape.

Unfortunately I don’t have any pictures of the process of getting the cryostat on, as I was helping Carolyn and the riggers. First we had to lift the cryostat and attach the bottom shields. Then we lifted the cryostat onto the gondola and screwed it into place. It was great to have the riggers helping as well.


The cryostat is integrated! It’s inside the white shields on the top layer of the gondola (the hoses coming out are attached to the cryocooler). Carolyn was setting up the cryostat monitor.


Here are some other pictures from the past couple of days:


Before we got the cryostat on, Carolyn and Alex noticed that some of the connectors on the shields were missing some nuts. Here they are shaking out one of the (very heavy) shield pieces hoping that the missing nut would fall out.


I’m making a box to hold a raspberry pi (a tiny computer). The raspberry pi will read some extra temperature sensors, because we wanted to add more than we had room for in the flight computer. I’ve never machined a box before, so I was very proud of my first connector hole.


All of the connector holes in the raspberry pi box! I don’t think I’ll become a machinist any time soon….






Shipping Trouble

We keep getting delayed due to shipping, which is pretty frustrating. First, we had to wait to get the card cages sent from Berkeley. As soon as we got those last week, we thought there was nothing preventing us from getting the cryostat on the gondola. But that was before we noticed that our stycast (thermal epoxy) had dried out. We need the stycast to attach heaters and temperature sensors to the cryostat, the electronics boxes, and the gondola.

Brent ordered some more stycast from a place in Europe that claimed they could ship it in 2-3 days. But someone else from UC Berkeley also ordered something from this same company, so the company got confused and sent the stycast to Berkeley. Once we figured out what happened, the company re-sent us the stycast, this time to Wanaka, but it probably won’t arrive until Tuesday.

While we wait, we’ve been working on a lot of the other aspects of the instrument. Alex added some connectors to the flight computer (unfortunately I didn’t get a photo of the flight computer, which looks pretty cool when it’s opened up). Abby, Jimmy, and Alan got all the card cages on the gondola.



The card cages mounted on the gondola. Can you see Carolyn in there? Hint: look for her feet.



Carolyn in the gondola (from another angle). She was routing all the cables from the card cages to the electronics bay.


The inside of the gondola–the card cages are mounted on the other side of the metal plates. You can see the result of Carolyn’s cabling work. She wants me to assure everyone that it’s not finished yet and will look a lot better when she’s done (though I think it looks pretty good already). There will also be a lot more cables there when she’s done.

While the cryostat is on the bench, Carolyn turned on all the detectors and started taking some calibration data. All the detectors look good!


Looking at the data through the GSE, the program that  monitors the instrument from the ground. The red display shows how a single detector is illuminated. Each detector has 37 strips on each side and can be divided into pixels. The brighter the red, the more counts each strip has. The plot in the upper left shows an energy spectrum of one of the detector strips.

I’ve been working on setting up the pump system. To better control the cryostat temperature in flight, we are going to pump fluid (kind of like antifreeze) through the cryocooler and then through a huge copper plate. The fluid will take the heat from the cryocooler and radiate it away when the pump is running.


The pump system on the bench in front of the cryostat. You can see the radiator plate and reservoir (the white can) that holds the fluid. The pumps are underneath the radiator plate. All of the bubble wrap around the cryostat is to protect the very sensitive signal cables that go between the cryostat and the card cages.

We’ve also been working on the shields. The shields block gamma rays from the bottom and sides of the instrument so that we only see gamma rays from space.


The shields on the other side of the cryostat. In flight, the shields surround the bottom and sides of the cryostat. Even though they’re not in their flight configuration, we can still calibrate and test them. You can also see the PDU (power distribution unit) below the cryostat.

Brent has been working on an alert system for flight. Because we’re hoping for a 100 day flight, we don’t want to be monitoring 24/7 during the entire flight. The alert system will text and email us if something goes wrong with the instrument.


Brent made the alert system talk every time there’s an alarm. We also found a cheap strobe light in an electronics store, so Brent hooked it up. Now every time there’s an alarm, Brent gets a text, the strobe light gets going, and we hear “COSI ALERT. ERROR ERROR ERROR” in a pretty weird computerized voice.

McBride worked on building a box to hold what we call the ‘ethernet switch switch’: a switch to turn on and off the ethernet switch.


McBride working on the box in a patch of sun. Alex described him as looking angelic.


We’ve also been having fun! (Today is Sunday funday after all.) Last night we went out for dinner and a couple beers after. Today we didn’t do anything as a huge group, but a lot of us hung out by various lakes. As I write this post, Brent and Carolyn are BBQ-ing what looks like a delicious dinner for everyone.


Brent, Abby and I split this watermelon margarita last night. It looked much better than it tasted.


Carolyn, Brent and I sat by the lake for a bit this afternoon. Carolyn was the only one who went swimming.


In other news, the cat is still desperate to get inside the house (but can’t because Brent is allergic). We opened a window in the kitchen and the cat immediately jumped in. Carolyn had to push her back out.

Sunday Funday

On our first day here, some of us took a pact to take a day off every week: Sunday funday! (If the weather is bad one Sunday we can do a Monday funday instead – it still rhymes). Yesterday most of us hiked near the Rob Roy glacier and got some great views. Here are some pictures from the day.


Getting to the hike itself was an adventure. We had to ford about 8 streams in our cars.


View from the beginning of the trail (or track, as they say here in NZ). The hike mostly followed this river. We could already see the glacier in the distance.


Looking back at the valley


The lower viewpoint


Part of the group (Carolyn, Jimmy, McBride, and Brent) on the way to the upper viewpoint


The upper viewpoint, where we had lunch


Relaxing at the top


Alan had four cameras with him. He said he’d “only take 500 or 1000” photos that one day.


Brent tried to find a more comfortable rock


A waterfall coming off the glacier. There were a couple more but I didn’t manage to get a good photo of all of them.


Looking at the valley on our way down


One of many fields of sheep along the road to the hike



First week in Wanaka

Not too much has happened this week. We’re still waiting for some of our card cages (the electronics that read out the detector signals) to get here from Berkeley. They got shipped separately from the rest of the instrument because we wanted to work with them during the month it took the container to get here. Once we get the card cages, we’ll be able to turn on the rest of the detectors, and start putting them on the gondola.

In the meantime, we’ve turned on half of the detectors, and they look good! We’ve also been working a lot on software.

Here are some pictures from this week:


Here’s a classic photo of McBride with his head in the PDU (power distribution unit). The PDU distributes power from the batteries to all of our electronics.


We checked out the brewery down the road for lunch one day, but they didn’t have much in the way of food. Some of us enjoyed a beer instead.


CSBF hooked up some cables for telemetry. There were more than Brent was expecting, so he was confused.


Carolyn and McBride made a ton of lasagna for lunch last week. Here they are picking the cheese off the unbaked lasagna.


Brent brought a fancy coffee maker from home. It involves a grinder, but the grinder only works on American power. To use it at our house in New Zealand, we had to bring this huge transformer from the lab.


Our house came with a cat! We don’t know his/her name, so we call him/her Kitty, Meow, or Fuzzball.


The cat has started sleeping in my bed at around 5AM every morning.

First day in Wanaka

Alan, Alex, Brent, McBride and I arrived in Wanaka yesterday afternoon. This was basically the first thing we saw:


We had lunch, got settled in, and met up with Carolyn. She got here a week before us to get New Zealand radioactive source training and meet the shipping container. Alan, Alex, Brent, Carolyn and I are staying in a huge house together, while McBride has his own place. Our house has some great views of the surrounding lake and mountains, as well as an outdoor grill, a hot tub, and a swimming pool (though who needs that when you’ve got a lake next door?). There’s also a cat!

Today we checked out our work space for the first time. Carolyn had already unloaded the entire shipping container with the help of CSBF. It’s pretty great that our building is already built and we’re able to unpack and get set up. (Remember the weather port struggles in Antarctica?)

The Wanaka airport seems like a pretty nice place to work. We can see mountains in any direction we look. There’s a cafe right across the street that has good sandwiches, which is a convenient lunch spot. There’s a brewery a few minutes away which we want to check out at lunch tomorrow. We’re also right next door to a helicopter launch pad, so hopefully we’ll get to go for a ride sometime. Throughout the day we heard helicopters or small planes taking off or landing.


Everyone at the airport cafe for lunch


Walking back to our building after lunch


The airport


View from our building’s back door


We are right next to helicopters!


Another airport view

We spent a lot of today getting set up. The first major thing we have to do is get everything on the gondola. That will probably take us at least a week, because we have to pump down and cool the cryostat. Then we want to turn on all the detectors to make sure they’re working. Once the instrument is built up, we’ll be testing everything and doing calibrations. Eventually we’ll have our hang test, where we make sure that our instruments work well with all of CSBF’s systems in order to confirm that we’re ready for flight. After that comes the launch, but that won’t be until April 1 at the earliest.


Carolyn working on the empty gondola


McBride decided that he needed 5 computer screens this time

COSI 2016!

Sorry to leave you all hanging for so long. It’s been a busy past year for COSI! And it’s about time that we caught you up on what we’ve been working on.

First and foremost, COSI is just about ready to launch again! We’re launching from another Super Pressure Balloon this coming April, except this time, instead of being in the freezing cold of Antarctica, we’ll be the first science group to launch from CSBF’s new site in Wanaka, New Zealand! And we’re all looking forward to a much longer flight.

The last post in the blog was the disappointing news about the COSI’14 flight terminating early after a meager 2 days at float due to a leak in the ballon. The silver lining to the instrument coming down so early is that it landed relatively close to McMurdo Station, meaning it would be a fairly straightforward recovery. If you want to hear more about my Antarctica recovery adventures and check out all of the pictures, look my other post from today titled “COSI’14 Recovery.” I’ll pick up the story here starting with the delivery of all of the COSI instrument back to Berkeley in March 2015.

Before any decision could be made about COSI’s future timeline, we needed to check the status of our detectors. We pumped down the cryostat and turned on the cryocooler right when the we got it all back in April. And, low and behold, each of the twelve detectors came up working well; none had been damaged during the flight/landing/shipping! We had the whole readout pipeline running in our lab within a couple of weeks, so when the Balloon Program Office offered to have us fly out of Wanaka in Spring of 2016, we felt pretty confident we could be ready in time.

One major hurdle that we had to pass over was disassembling the cryostat. One of our twelve detectors had 10 bad strips, so given the opportunity, we wanted to see if it could be refabricated to be fully operational. In August (after I passed my quals!), we disassembled the cryostat and removed one of the detectors for refabrication. Everything was put back together in September and we started system tests immediately.


Chris Cork, a retired SSL engineer who used to work with the LBL Detector Group, graced us with his presence and took the lead with the cryostat integration. Here he is putting the new and improved germanium detector into the stack.


The COSI cryostat put together again! At the same time as refabricating one of the detectors, we developed a new temperature regulation system for the cryoscooler. You can see the copper tubing around the cryocooler here.

Before our flight from New Zealand we needed to pass a compatibility test with CSBF in Palestine, Texas, just like in Summer 2014. But, due to the fact that COSI’16 is almost identical to COSI’14, both teams agreed that a simple compatibility,with just the power system, flight computer, and one card cage would be sufficient. Brent, Alex, and McBride spent a leisurely 10 days working in Palestine to pass the COSI’16 compatibility test (but none of them took any pictures!).

We had another trip to Palestine this past November to use their thermal vacuum chamber. We wanted to put our cryostat and electronics through more rigorous testing before our flight. In their BEMCO chamber we are able to simulate the space environment through day and night cycles. It’s pretty anti-intuitive, but flights from New Zealand will have colder temperatures than flights from Antarctica, this is not only because we’ll be going through night cycles, but you can get some very cold storms over the ocean. The temperature in flight can reach as low as -100 C, but with foam surrounding the gondola we should be able to maintain a balmy -40 C in the electronics bay.

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Clio and McBride monitoring during the BEMCO test. Clio’s written a whole new GSE (Ground Support Equipment, i.e. the program that we use to talk to and monitor the instrument) in the past few months, so this was a great opportunity to test it!

Once back in Berkeley, we had the month of December to fully integrate the gondola and do some system testing and calibrations before packing up.

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Clio installing the new cryocooler cooling system. We’re pumping liquid fluorinert (environmentally friendly!) through the cryocooler and out to a radiator to keep everything a moderate temperature in flight.

Clio installing the new cryocooler cooling system. We’re pumping liquid flourinert (environmently friendly!) through the cryocooler and out to a radiator to keep everything a moderate temperature in flight.

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COSI gondola fully operational in Berkeley. The California winter months are perfect for calibrations in the SSL highboy.

We shipped everything out on January 6th and we’ll be meeting the container in Wanaka on the 15th of February! We’re all so excited about the next few months! GO COSI CO!