The UIUC ATLAS TileCal Project Niall Nethercote UIUC High Energy Physics Summer 1998 Project Head - Dr. Steven Errede

Contents Ê Background on Experimental Particle Physics Ë The World-Wide ATLAS Project Ì The UIUC ATLAS TileCal Project – Sub-Module Fabrication – Photomultiplier Tube (PMT) Testing Í Our Web Site

Experimental Particle Physics

Particle Accelerating Facility n Accelerating Ring n Detector

How is a Particle Detected? n Accelerate some matter (e.g. the quarks of protons) n Collide the quarks (and get a mess of gluons) n Interesting particles may form (e.g. top quark) n Detect the residual particles (e.g. w/ a PMT)

The World-Wide ATLAS Project

CERN n CERN is the European Laboratory for Particle Physics n CERN is located in both France and Switzerland n It is very near Geneva, Switzerland

Enlargement of the LHC

The LHC Project n Large Hadron Collider (LHC) Ring n Compact Muon Solenoid (CMS) Detector n A Toroidal LHC Apparatus (ATLAS) Detector n CERN is upgrading in three major ways

The ATLAS Project n 144 institutes world- wide are collaborating on the ATLAS project n ATLAS is 5 stories tall! n ATLAS will detect proton-proton collisions n Its center of mass energy is 14 TeV! n ATLAS will start taking data in 2005

The UIUC ATLAS TileCal Project

UIUC and ATLAS n What part of ATLAS does the UIUC group work with? n Sub-modules are made of alternating layers of steel and scintillating tile (shown in next slide) n Groups of sub-modules are modules n Groups of modules form the Hadron Calorimeter n The Scintillating Tile Hadron Calorimeter (pictured green)

What Does the UIUC Group Do? n The UIUC ATLAS project is two-folded –Sub-Module Fabrication –Photomultiplier Tube (PMT) Testing

Hadron Detection n How are hadrons detected with sub- modules and PMTs? –Hadron flies through scintillating tile and photons are released –Fiber optics route some photons to a PMT –Photons hit PMT and convert to photoelectrons (via photoelectric effect) –Electrons are multiplied inside PMT and a detectable signal results

Sub-Module Fabrication n UIUC’s sub-module assignment n Glue machine n Prototype sub-module production

The Sub-Module Assignment n In the extended barrel 9 sub-modules make up a module (and also recall that there are 64 modules circling around the beam axis) n So when you do the math it turns out that we are making about 1/3 of an extended barrel n UIUC is responsible for producing 200 extended barrel sub-modules

Glue Machine n The glue machine will be used to apply very precise amounts of glue to the sub- modules n It is currently being constructed and will be ready for early 1999 when we begin to make some more sub-modules n Dr. Errede and Fred Cogswell (our machinist) have put the most work into the glue machine

Sub-Module Prototype Production n During the Winter of we constructed some prototype sub-modules

Photomultiplier Tube (PMT) Testing n General –UIUC’s PMT testing assignment –Our PMT testing setup n The work that we did this summer –Dark Box modification –PMT Aging experiments

The PMT Testing Assignment n When ATLAS begins data taking it will be using approximately 10,000 PMTs! n Here at UIUC it is our job to test over 3,000 of those PMTs (i.e. about 1/3 of ATLAS’s PMTs)

Our Laboratory n Here is a shot of Dr. Errede’s Laboratory n Note the crates and the dark box

Our Dark Box n Here the crates are on the left, the dark box is on the right, and that’s Jori walking into the lab n The mess of wires that run in and out of the dark box n The dry nitrogen system can also be seen

Inside the Dark Box n This is our PMT testing layout that is housed in the dark box

Dark Box Modification n Our group needs to prepare for the testing of the over 3,000 PMTs n The biggest task is modifying the dark box so that it can test PMTs at one time n The dark box modification projects are: –Adjusting the layout of the dark box < Stepper Motor < Filter Wheel –Increasing the amount of light to the Photodiode < Faster Transistor for the Pulsing Circuit < Charge Cable < Optics

The Stepper Motor n The stepper motor will be used to move components around inside the dark box n Before this summer Jori Ruppert-Felsot worked with the stepper motor n Then when the summer began John Patti and Mike Griswold finished up the task

The Filter Wheel n The filter wheel will be used to vary the intensity of the light goes to the PMT n The stepper motor will rotate the filter wheel

The Photodiode Needs More Light n Three different attempts at supplying the Photodiode with more light have been attempted this summer n Mainly Jori Ruppert-Felsot, Dan Dombeck, and I have been working on this n For the most part all attempts have been unsuccessful –Using a faster transistor or a circuit that incorporates two transistors –Hooking a charge cable up to the LED –Setting up an optics system that can focus light onto the Photodiode

PMT Aging Experiment n About one month ago we received a new 4 th generation PMT (8C28R3) from CERN n We proceeded to test its aging characteristics n The new PMT was pulsed at a number of different frequencies for one week n The tests on this PMT ran for time intervals of approximately 24 hours n During our testing, the PMT experienced an equivalent of 50 years of running at ATLAS n Important Quantities: N pe and the Gain

PMT Aging Experiment Results

Conclusions and Then Continuation n We concluded that the gain of the new 4 th generation PMT actually increased slowly while it was being pulsed for 50 equivalent years n This is rather odd. The PMT’s performance is seemingly improving as it ages?! n Possible explanation: charge may be collecting on the walls of the PMT, thus creating an electric field that focuses the e - n We then proceeded to perform more aging experiments on older 3 rd generation PMTs that we had available in our lab

The UIUC ATLAS TileCal Web Site

A New Look n During the middle of the summer I completely revamped our ATLAS Web Site n The URL for our Site is: n But lets first check out what the Old Site looked likeOld Site

Thank You’s n I would like to thank the following people for teaching me so much this summer: –Jori Ruppert-Felsot–John Patti –Mike Griswold n And especially: –Dr. Steven Errede –Daniel Dombeck

The Musings of John Patti n This was John’s reaction when I told him how much work I was going to put into my presentation