Research Masterclass - 2009 Lecture 2 Steve Watts Physics and Astronomy, University of Manchester.
Advanced Detector Design for Particle Physics (A story of designing an upgrade for ATLAS)
Now what technology do you need to build a detector to get the data to do the physics ???
Tracking 7 TeV protons at 220 and 420 m from the interaction point at the LHC
Note: lecture will be delivered in the form of a research seminar….. LAST WEEKS HOMEWORK ……
Hint: Lorentz Force Non-relativistic OK
Whats happening At Fermilab ?
Physics blogs… SILICON TECHNOLOGY MAKES STRUCTURES AT THE
LEVEL OF NANOMETRES……
IN PARTICLE PHYSICS WE ARE HAPPY WITH MICRON LEVEL
( 1 micron = 10-6 metre. Human hair around 50 microns)
(ASIDE: WE USE 0.25 micron TECHNOLOGY ELECTRONICS)
CAN USE THIS TECHNOLOGY TO MEASURE CHARGED PARTICLE POSITIONS AT THE FEW MICRON LEVEL.
VITAL FOR IDENTIFYING PARTCLES CONTAINING CHARM, BEAUTY AND TOP QUARKS.
WE USE A TECHNOLOGY THAT WAS DEVELOPED FOR MAKING ELECTRONICS, MICROPROCESSORS AND IMAGING SENSORS Charles K. Kao working with fiber optics at the Standard Telecommunication Laboratories in England in the 1960s.
Bell Labs researchers Willard Boyle (left) and George Smith (right) with the charge-coupled device. Photo taken in 1974. Photo credit: Alcatel-Lucent/Bell Labs.
PHYSICS NOBEL PRIZE 2009
Half of this year's Nobel Prize in Physics went to Charles K. Kao, center. The other half of the prize was shared by two researchers at Bell Labs, Willard S. Boyle, left, and George E. Smith. e2v CCD Imaging Sensors Enable NASA's Hubble Space Telescope To Explore The Universe May 12, 2009 Today, e2v Charge Coupled Device (CCD) imaging sensors are being launched into space by NASA, on board the space shuttle Atlantis, as part of a mission to upgrade and repair the Hubble Space Telescope. e2v CCD imaging sensors will equip Wide Field Camera 3 (WFC3), a new instrument that will be installed on Hubble to take large-scale, extremely clear and detailed pictures of the universe over a very wide range of colours. e2v's CCDs will make the Hubble telescope more powerful than it's ever been. e2V are a UK company based in Chelmsford – now the world leaders in CCDs for scientific imaging
http://wfc3.gsfc.nasa.gov/technology/detectors2.php
The WFC3 UV channel utilizes two 2x4K pixel CCD detectors from E2V Technologies. By coating the detectors with special anti-reflective coatings, they may be made extremely sensitive in spectral areas previously unavailable. The detectors are sensitive from a range of 200 to 1000 nanometers. http://www.hep.lancs.ac.uk/lc2009school/lectures/Ambleside-detectors-1.ppt
1995
September 1991 SLD Experiment – Vertex Detector Stanford Linear Accelerator Center (SLAC)
Run 33544, EVENT 6476 27-APR-1996 06:05 Source: Run Data Pol: R Trigger: Energy CDC Hadron Beam Crossing 1215252296
Track Properties
y
z x Thanks to Chris Damerell for pictures. Work of many people and groups !!
VXD2 480 1 cm2 CCDs VXD3 307 million pixels
centimeters 0 4.000 8.000 e2V CCDS
Releases about 24,000 Electron-hole pairs
3.66 eV per electron-hole pair
1 dE / dx ≈ 2MeVg −1cm2 × Density(gcm−3 ) β = (velocity/speed of light) β 2 Simplified Bethe-Bloch formula Density of silicon is 2.33 gcm-3
Minimum ionising particle (MIP) has β close to 1
How to track our 7 TeV protons at 220 and 420 m from the interaction point
Design Specification
Get as close to the beam as possible. Hamburg Pipe + Mechanics + Edgeless Detector
Radiation Hard 1015 –1016 charged hadrons per cm2
One micro-radian angular resolution. 10 micron per station separated by ~ 8 m
Assembly of sensors and mechanics at few micron precision
Repeatable assembly at 5 micron precision
Stable in temperature. 20-40 W per station Heat sink for this which will work in the LHC tunnel Two stations about 10 metres apart
A single tracking station Sensor is roughly 8 x 8 mm2 How many Joules in this beam ??? Basic concept and nomenclature
420m
Distance from beam = Machine safe distance (cf K. Potter) + 300 micron (window) + 300 micron (vacuum) + 50 micron ( alignment + active edge)
TrackingTracking Detectors:Detectors: atat 420m420m 25x5mm25x5mm2
3D silicon with active edges
50μmx400μm
124.5 mm
LHC DIMENSION RO TRIGGER BUFFER EXPERIMENT S SIGNAL
ATLAS 50x400 μm2 binary Internal fast- 2 - 6.4μs 50μ m 7.2x8mm2 and OR 40 MHz σ x,y ==14.4μ m time 12 over threshol d
Choose a reference point mid-point between two stations Minimises the error
Δx = σ/sqrt(Ν) δθ = δx/zref BUT only if points are uncorrelated. This is not true as the tracks have small angle
Can improve matters by offsetting alternate layers by 0.5 of the pitch. Paula Collins – ICFA 2003 Summer School
θrms = 1.94E-6 Sqrt (x/Xo) at 7 TeV per layer
Multiple scattering is 0.2 μrad per layer
0.2% interact per layer or 1 in 500 tracks interact per layer 50μ m σ ==14.4μ m x,y 12 Final plot showing the tracking precision in the FP420 Design Report ( look it up on the physics arxiv !!!!) DIRECTED WORK WEEK TWO
• Find some details of the 2009 Nobel Prize. In particular, look at the work of Boyle and Smith and understand how the device they invented operates.
• What signal in terms of electron/hole pairs would be created in a silicon detector by a 30 KeV x-ray. Hint: It interacts via the photoelectric effect.
• A charged particle traverses a 300 micron thick silicon detector. What signal would it produce if it were a) a minimum ionising particle b) a 30 MeV proton c) an alpha particle.
• What error on the 30 MeV proton angle would result due to multiple coulomb scattering ? Compare this to a minimum ionising particle.
• Why does a ruler with spacing d have a resolution of d/sqrt(12) ?
• Describe the features of fig 108 from the FP420 Design Report – overhead 25. See if you can be quantitative in your answer.
• How much energy is stored in the LHC beam at full luminosity. What would happen If this hit the 300 micron steel window of the Hamburg pipe, or the silicon detector? Try and be quantitative ! ADDITIONAL SLIDES FOR INTEREST ONLY ( D. Pitzl)
http://pdg.lbl.gov/index.html http://www.desy.de/f/students/summer_lectures.2009hep.html
http://hepwww.rl.ac.uk/damerell/2003/Vertex-detector-95-008.pdf
Chris Damerell’s report on silicon detector technology and how it is Used in particle physics Detect x-rays too with silicon sensors Thermal prototyping in the lab…….