Virtual vacuum leaks

I have a really good quote about vacuum leaks, and thought that I had blown the chance to use it, already having fixed one leak. Today I tried to restart the Stern-Gerlach experiment, and found that it had a huge leak in it. There was a very good reason for this: I had attached a light to the vacuum system to check whether it was aligned properly. This light was built in to what looks like a leak-tight metal plate, but which actually has a huge hole in it.

The picture below shows what happened: the air which was pumped out by the pump was continuously replaced by the air coming in through the leak. Now the funny thing is that the leak could only be heard by listening to the bellows, which I drew as being the zig-zaggy thing. At this point you could hear a hissing sound. This hissing sound couldn't be heard at the point where the air came in, only when it passed through the bellows.



After a couple of hours, and after installing a spare bellows which made exactly the same noise, I worked out what was wrong, and removed the piece with the hole in. For a while I was annoyed, but then I realised that I may have created a new musical instrument: the leakophone. Presumably by varying the tension in the bellows you could create a whole range of hissing sounds with various tones. Add a couple more bellows and you could play a lovely tune. Before I forget, that quote, stolen from R.K. Fitch who claims that it was a student's answer to an exam question.

The essential components of a high vacuum system are a rotary pump, a diffusion pump, and a leak

Black Humour

I read in the newspaper today the tragic death of Do Van Ky, a would-be Vietnamese immigrant to Britain, and I burst out laughing. You may find this heartless, for the story is a very sad example of what happens to many people who leave a life of poverty in their own country to seek a better life in the west. After somehow making his way from Vietnam to Europe, he entered England via Dover, hidden in the back of a lorry together with several others. Once in England, the immigrants tried to leave the lorry whilst it was still in motion, but Do Van Ky slipped and was crushed under the rear wheels of the lorry.

What could be funny about this? The unfortunate driver of the lorry was Stan Bowden, who couldn't be blamed for what happened. He summed up the event thus:

"A man made all that effort to struggle halfway across the world for a better life, he tried so hard, he must have been desperate. The first time he hit British soil, some bastard ran him over. That bastard just happened to be me."

This made me laugh. I don't know if you are supposed to laugh at such things, but it is probably better to laugh at these things than to ignore them, which is what I usually do.

An honest day's work

For the first time in god knows how long I actually worked properly today. I took the Stern-Gerlach experiment apart and stuck it back together again with a new vacuum chamber, which has been built by the workshop. Vacuum systems are a bit like a child's building set. Each component has a kind of connection at the end, which (hopefully) fits the connections of other components. This is commonly called a "flange". This means that once you get enough pieces you can build and rebuild your system in any way you want.

With a bit of luck it will work soon. The down-side of this is that I sacrificed the afternoon coffee and cake break.

Sacrificial offerings

No, no, no, despite the title of the post I'm not writing about Hermes. I am back in Erlangen, and back on track with my mission statement: today I cycled to Bamberg and drank a shandy. Bamberg is about 40 km from Erlangen, but I took the scenic route, stopping for lunch in the small franconian village of Teuchatz. Gasthof Neuner (that's the name of the pub in Teuchatz) is good for three reasons; it has cheap beer, a very limited menu (a choice of one of three lumps of meat, each served with salad and dumpling), and is on top of a hill. This means that you get 5 extra minutes to digest your dumpling before you have to go up the next hill.

A short while after lunch I passed a sign pointing to the "Jungfernhoehle", which translates as the "virgins' cave". Of course I cycled straight past it, suspecting that seeing the cave would involve a long walk, that the cave would be very much like any other, and that the virgins had probably taken the afternoon off.

In all these points I was probably right, but the cave has a most peculiar history. According to a local legend three virgins were beheaded in front of the cave and each October would go for a headless moonlit ride. Then in 1951 some members of the Engert family, living in nearby Tiefenellern, decided to dig out the cave in a search for treasure. They were eventually stopped by some local amateur geologists, and the digging, which had found only bits of bone, stone and pottery, was turned over to some proper archaeologists. After quite a bit of digging, they had quite a lot of bones, including 40 skulls of young girls each with a hole in the side. They also had an extra large cooking pot. Putting two and two together, the experts declared the cave to be a site of ritual sacrifice and cannibalism, dating back 4000-5000 years. The cross below (borrowed from wikipedia) is a memorial to the victims.



Is it a coincidence that the story of the beheaded virgins rose around a cave where ritual sacrifices took place? Many people, including Victor Harth (see link below) thinks that it isn't, and that the legends were passed down through the generations for several millennia.

Links:
Victor Harth describes the story, in german.

Two geologists from Erlangen mention the story in their article about something else. Also in german.

A Time article from 1953, which you have to pay for. I did pay for it, so if you really want to read it just [DELETED BY ENDOFPHIL LEGAL TEAM].

Hardon production in deep-inelastic scattering

This is not quite what Hermes is supposed to do! If you can't spot the mistake try clicking on Mr Ben Goldacre's website. I just made up the title of this post, but it seems that there are a lot of genuine high-energy physicists who have made this typo. The next ten years of particle physics suddenly looks much more exciting!

Suddenly appearing objects

I have very good eyesight, but sometimes I just don't see stuff. After three days in Hamburg I discovered that they had built a new police station right at the entrance to DESY. I managed to pass this building several times without noticing it at all, and was surprised to say the least when I got off the bus this afternoon right next to a police station.

I also spend three evenings in the control room of hermes and never noticed the bottle of champagne which has a label declaring that in should be opened "for the first recoil proton". The new detector at hermes is called a recoil detector, as it detects things which are going forwards, but not as much forwards as other stuff which is going forwards. This means that anybody who happens to be going forwards at a good rate themselves would conclude that the stuff detected by the new detector is actually going backwards.

So if the new detector ever detects one of these "recoil protons" it is time to open the bottle of champagne. At the moment the recoil detector is in lots of small parts, and the experts are welding and hammering it back into shape. To be honest, I think that buying champagne and labelling it "for the first recoil proton" is a rather safe investment.

Hamburg

I went for a nostalgic bicycle ride around Hamburg today. I went to the english bookshop on Stresemannstrasse 169. I didn't buy any books, but I bought a packet of teabags, a tin of drinking chocolate (Hi Juliane!), some malt vinegar and two packets of biscuits. The malt vinegar is the last missing ingredient for a fish and chips, which I will try when I am in Erlangen again. I got my hair cut at the old barbers, drank a coffee in Ottensen, and bought a set of ping-pong balls.

I used to have a life here in Hamburg with lots of nice things. Somehow I let the bad stuff take over and I gave it all up.

Key Access

I am back in the east hall of the Hera ring, looking after the Hermes experiment. Things have changed since I was here in November. The polarised target, which was my special bit of apparatus, was removed and replaced by a new detector.

The most obvious things here are the gaps. The new detector has gone into the place of the old polarised target, but it isn't as big. There are now places you can walk where you used to have to climb or crawl. There are gaps in the array of electronics, too, whole racks are missing. The odd thing is that nobody pushed the remaining things together, they just left the holes as they were, as a kind of reminder of what used to be.

One thing that hasn't changed is the chance for a key access. The experiment and accelerator are enclosed behind concrete blocks, and you can't get into the experiment when the accelerator is running because of the high radiation levels. If there is a short break then it is possible to go inside and try to mend the odd broken cable. To do this you have to talk to some guy in the accelerator control room, and say who you are. The sound system is really bad, though, so the guy just makes his best guess as to what you might be called. Of course you can help by giving some context: "Nass wie feucht" or "Vogel wie Tweet Tweet" [1]. Then you are allowed to take a key, and pass through the gate. Today we went in and reattached one cable, and swapped two others round.

[1] I have a collaborator whose name translates as "Wet", and one whose name translates as "Bird". For such circumstances it is easy to pass on the correct name.

München

This weekend I am in Munich, visiting Britta, Max, Konstantin and Helena. Konstantin is 3 years old, and Helena 4 months. Yesterday we went for a walk through the English garden, which was originally designed by one of my heros, Benjamin Thompson, later Count Rumford. A nice long walk with lunch in a beer garden is always good for the soul.

Stern-Gerlach sort of lives

I have been quite busy trying to get the Stern-Gerlach experiment to work. After fixing the leaky flange I tried to run the experiment. Yesterday I saw the first signs of a beam of potassium atoms. It wasn't really a beam, more of a diffuse flow from the oven to the detector, but I guess that once you measure some potassium atoms it is a matter of time until you get the thing working.

I think that the reason I didn't see a clear beam was because I didn't put the detector together properly. The detector consists of a hot tungsten wire and a collector plate. The plate has a hole in it to let the beam of potassium atoms through. They should then hit the hot wire where they lose their outer electron. The remaining potassium ions are then attracted to the plate, which is at a potential of -9V compared to the wire.



The problem is that when I took another look at the detector the wire wasn't directly beneath the hole in the plate, but had slipped to the side. This means that atoms from the beam could not be detected, only those which had somehow reflected off a wall somewhere.

Call to Arms

Next week I get to go to Hamburg to help out Hermes, in an effort to at least to show willing. The following play for three people sums up the situation. I don't know quite who the other people might be, but I am one of the folk dancers.

Act 4 scene 2.

A fort somewhere, at some time. The captain walks the ramparts, taking stock and surveying the damage from the previous day's bombardment. In the background the remaining bodies are being disposed of.

enter Lieutenant

Captain: What news bringeth ye.

Lieutenant: The enemy hordes are amassing, sir. Their construxion of the siege weapons runs apace. Our supplies are low, the powder is short. The west wall is but a ruin. We cannot hold for much longer.

Captain: Yet hold we must. Avast, what spieth I.

Lieutenant. A messenger of the King! What chance relief?

Captain: Open the gates! Let the messenger arrive.

enter messenger.

Messenger: I bring news, Sir, from the king.

Captain: Hold not your tongue! Which news do you bring.

Messenger: The king acknowledges your request for support.

Lieutenant: Yes, is the Cavalry brigade underway? Are the 18 pounders being towed as we speak?
Has the counter offensive on the eastern flank set forth?

Messenger: The king did his best to fulfill your request, Sir. Alas, the cavalry are preparing for the royal wedding and could not be spared. The artillery are stuck east of the river and cannot cross until after the bridge is officially opened. However, his highness sends news of reinforcments.

Captain: Reinforcements, what form do they take? When will they arrive?

Messenger: They are on their way as we speak, Sir. Hark, I hear them now.

Lieutenant: I hear but the sound of bells and and song. Which regiment shall it be.

Messenger: No less than the queens own folk dancers. It is the most which could be spared, Sir.

Lieutenant: What use be the folk dancers against the combined Mongol horsemen, Zulu Impi and Martian tripods amassed against us?

Captain: The world champion chip awaits. Let battle comments.

Shifting sand

My name is Phil, and I am a member of the Hermes particle physics collaboration. There. I said it. I spent over three years helping to keep the Hermes experiment on the road, and in the end I went a bit mad. I stopped doing any useful work at the start of 2005 and have been trying to sort out my head ever since. Perhaps mad is the wrong word: to be more accurate I had psychosomatic illnesses and depression, which is probably what most people whould call mad, loopy, off your trolley, a wafer short of a silicon detector or whatever. I willingly invited people to knock me out and stick an endoscope down my stomach, when there was nothing wrong with my stomach at all, and if that isn't madness it certainly isn't quite the behaviour of a normal-thinking person.

If I had any principles about me I would have quit the Hermes collaboration on the 24th February, right after I finished my PhD exam. I would have written a mail to the whole collaboration and told them that their beloved collaboration was a rotten mess of an overworked workaholic management, overworked frustrated students, numerous hangers-on who were concentrating on other projects but sticking around to get their names on the publications, and senior scientists who had lost touch with the daily reality of what was happening. This would have left me unemployed but with my dignity intact. As it is I have become a hanger-on, somebody who is there in name but does practically sod all to help the collaboration. I let others work themselves to stupidity so that I can stick my name to some publication which I don't properly understand.

The Hermes experiment seems to be in a critical state. It wasn't feeling well, so someone stuck an endoscope down its machine equivalent of a tummy and it did the machine equivalent of spewing up its guts in the examination room. The next few days/weeks will decide whether there is a future (other than as radiation enriched scrap metal) for this experiment.

In the circumstances, I did the only thing possible: I took the afternoon off work to help vogelchr fill his sand pit. I feel that this was a worthwhile project. There was a plan, we carted some sand, and the result was one sand-filled sand pit, and at least two sand-covered children.

Cherry Blossom

Considering that it says in the title of my blog that I will try to cycle and drink the summer away, I have written remarkably little about cycling or drinking. I've been doing quite a bit of both, but in a rather unremarkable 50 km here, one litre there kind of manner, which doesn't really lend itself to writing about.

Well today I went for a very nice bicycle ride in and around "franconian switzerland". Franconian switzerland is a natural park just outside Erlangen, and is quite hilly, but lacks the major mountains (and yodellers and banks and ...) that its name suggests. It was rather windy, but also warm and sunny. And for about 20 minutes between Geschwand and Bieberbach everything came together. I had just eaten a ham and lettuce sandwich, the sun was shining, there were no cars at all, the wind was on my back, and the road was lined with cherry trees, each of which was in full blossom.

Tutorial

I held a tutorial for some students who aren't studying physics, but need to take a physics course. Of the 20 people only five turned up, but the five who were there were friendly, quite well prepared and happy to complete the exercises on the blackboard. This is good, as I tend to get rather confused when writing things on the blackboard. My main problems are that I can never quite decide which symbol to use to represent a physical property (there are just too many options), my rho looks like a p, I randomly drop symbols and I sometimes say something completely different to what I write. I also have a habit of losing the piece of paper with the answers on, and slowly taking all the pieces of chalk and depositing them randomly around the room. I think that I could have a long career as a lecturer in front of me.

As I say, it turned out very well, as the students rapidly gained in confidence and were quite happy to complete the exercises themselves, which is the point of the whole thing anyway.

If you want to read a more interesting blog than this one, I would suggest the BBC political editor, Nick Robinson. Tony Blair today effectively sacked his under-fire home secretary, Charles Clarke, after a some rather disappointing local election results.

I’ve often interviewed resigning ministers, but this was amongst the bizarrest. When I was called to be told the news, I was naked in bed in a Westminster hotel hoping to get at least an hour’s sleep, having stayed up all night covering the local elections. The interesting discovery I’ve made is that you can go from being in bed to attending a resignation statement in exactly seven minutes.

A small contribution to anglo-german friendship

What better way to improve the relations between england and germany than a charity football match with ex stars (Paul Gascoigne, Lothar Mattheus, Thomas Haessler, John Barnes), pop stars (Herbert Groenemeyer), other sporting figures (Boris Becker) and the right honourable member of parliament for Henley, Boris Johnson?

You may think that such a game would be a timid affair, with lots of pussy-footing around and no hard tackling. You would be wrong. Take a look at this video with the floppy-haired Boris Johnson in the starring role!

There is also a description of the match in the Daily Telegraph.

Missing

I live together with five other people in a shared flat. If you're reading this guys, czesc! That's polish for "hi", as four of the five come from Poland, and the other gave in and decided to learn polish. Csesc is the only polish word I know which is fit for print. Anyway, we get along fine here, and go out occasionally, and sometimes cook together, and as long as nobody mentions the word "Putzplan"[1] we get on just great.

The thing is, I never knew that my co-inhabitants really cared about me. So when I left for the weekend without telling them that I'd gone, I assumed that they would classify my disappearance as somebody else's problem. That's the good thing about sharing a flat with five other people. You don't really miss the odd person.

In any case they really did notice that I wasn't there and tried to ring me. Having failed (I somehow turned my mobile off), they got the name of a work colleague, found his home number in the telephone book and rang him up. Not really getting into the spirit of things he told them that I was in Duisburg (which was true) instead of saying that I had muttered something about a game of Russian Roulette (which would have been a rather whopping lie).

So here's to my caring flatmates. I missed you guys too. Just don't mention the Putzplan.

[1] The Putzplan is a table of recipriversexclusive name entries. The only person guaranteed not to clean the flat in a given week is the person who should do it according to the Putzplan.