Silicon
A single readout module from the silicon vertex detector of HERA-B, an experiment at the DESY laboratory in Hamburg that attempted to further our understanding of CP-violation (why there is lots of matter in the universe but hardly any antimatter).
I helped to assemble and test these little beauties and was given a dead one as a leaving gift, which I treasure. Finally I have the gear to photograph it, I hope I've done it justice.
On the right is a silicon wafer about the size of a credit card, and much thinner. In operation it was charged to about 1000 volts. Any particles zapping through it left a tiny charge which was picked up by one of the thousands of little sense wires etched into its surface, carried down the green flat cable in the middle, and then measured, digitised by the readout chips on the left and stored. It could be read out on request into computers that would use those 'hits' to reconstruct the path of the particle. All in a fraction of a second. Clever stuff. There were about 60 of these attached to carbon fibre 'arms' that could be moved around independently (and very precisely) inside a big vacuum chamber about the size of a car. In 1999, this was seriously cutting-edge stuff, though the LHC experiments at CERN are now even more impressive.
These were hand built, by the way. You're not looking at something churned out by robots in a Taiwanese factory. The wafers and chips were manufactured for us by commercial companies like Sintef, but they arrived in little boxes like hi-tech Lego and were glued, soldered and bonded by the technical staff at the MPI for Physics in Munich.
Silicon
A single readout module from the silicon vertex detector of HERA-B, an experiment at the DESY laboratory in Hamburg that attempted to further our understanding of CP-violation (why there is lots of matter in the universe but hardly any antimatter).
I helped to assemble and test these little beauties and was given a dead one as a leaving gift, which I treasure. Finally I have the gear to photograph it, I hope I've done it justice.
On the right is a silicon wafer about the size of a credit card, and much thinner. In operation it was charged to about 1000 volts. Any particles zapping through it left a tiny charge which was picked up by one of the thousands of little sense wires etched into its surface, carried down the green flat cable in the middle, and then measured, digitised by the readout chips on the left and stored. It could be read out on request into computers that would use those 'hits' to reconstruct the path of the particle. All in a fraction of a second. Clever stuff. There were about 60 of these attached to carbon fibre 'arms' that could be moved around independently (and very precisely) inside a big vacuum chamber about the size of a car. In 1999, this was seriously cutting-edge stuff, though the LHC experiments at CERN are now even more impressive.
These were hand built, by the way. You're not looking at something churned out by robots in a Taiwanese factory. The wafers and chips were manufactured for us by commercial companies like Sintef, but they arrived in little boxes like hi-tech Lego and were glued, soldered and bonded by the technical staff at the MPI for Physics in Munich.