Minimum Bias Trigger Scintillator Counters (MBTS) for early ATLAS running
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Transcript of Minimum Bias Trigger Scintillator Counters (MBTS) for early ATLAS running
02/10/2004
Minimum Bias Trigger Scintillator Counters (MBTS) for early ATLAS
running
M.Nessi
ATLAS week, Freiburg
02/10/2004 Marzio Nessi
MBTS
Why: In the commissioning phase of ATLAS, we need to have an effective means to trigger on physics and to veto halo events.
What : scintillator counters with some segmentation in eta and phi,
able to detect 1 minimum ionizing particle
Where : on the front face of the LAr endcap cryostat, covering the radial dimension of the Inner Detector
When : needed in 2007 for the first beam, 3-4 months at low luminosity (5*1032); it will be dismounted
during the first shut down
02/10/2004 Marzio Nessi
MBTS readout
It will be to difficult to bring inside ATLAS new PMTs, cables,..
The idea is to use the same optical path used for the existing crack scintillators. Optical cables will transmit the light signals from the counters to the existing connectors in place for the crack scintillators
Each PMT in the tile drawers, used for this purpose, will then be linked to the LVL1 trigger processor or equivalent
PHI segmentation of 8 should be enough. This can still be tested by simulation.
Eta segmentation of 2 is planned. Radius or eta of segmentation to be defined. Limit of Pixel detector?
02/10/2004 Marzio Nessi
MBTS Geometry
On each side a disk of scintillator Rmin=138 mm, Rmax=1200 mm
Rmax can still be optimized.
Two options:Each disk will either take the place of the JM moderator
disk or be mounted in front of it
Maximum thickness of the disk, including supports and eventual readout system Z= 30 +- 1 mm
02/10/2004 Marzio Nessi
MBTS Segmentation
Current design forMTBS counters
Inner eta segment covers pixel detector
Eta = 1.8 (1200 mm)
Eta = 2.8 (431 mm)
Eta = 3.8 (1.58 mm)
02/10/2004 Marzio Nessi
Possible mounting scheme
MICHIGAN STATE UNIVERSITYHIGH ENERGY PHYSICS
REV. SCALEDWG. NO.
TITLE
PARTS LIST
PART NO.ITEM DESCRIPTION QTY.
DATE 16 DEC 03
DRAWN RON RICHARDS
PROJECT MBTS
MATERIAL
UNLESS SPECIFIED:
DECIMALS ±
FRACTNS ±
ANGLES ±
BREAK ALL EDGES
DO NOT SCALE DWG
MBTS MTG. FRAMES
"NOSE" DETAIL:
OUTER RADIUS CLIP HOLES
ONLY TWO TYPES OF FRAMES
02/10/2004 Marzio Nessi
MBTS Optical readout
The requirement is to have enough light in the PMTs to easily detect minimum ionizing particles
The light budget should allow a degradation of the light output by a factor 2 because of radiation damage during its short lifetime
Standard technique is scintillator readout by wavelength-shifting (WLS) fibersalong edge of scintillatorcan also try fibers embedded in groove in scintillator
02/10/2004 Marzio Nessi
Prototype construction
Prototype construction currently proceeding using 2 cm thick scintillator provided by Dubna
This is the same type of high-quality scintillator used in the CDF central pre-radiator upgrade currently underwaysomewhat different
design but there we get >12 pe/mip
WLS fibers for prototype will be along crack in middle of scintillatorfabrication is more
efficient with scintillator in 2 pieces
inner
outer
02/10/2004 Marzio Nessi
Next steps for MBTS
Prototype counter will be completed this month We will test prototype counter with cosmic rays at CERN using ATLAS
readout If design and light-yield proves adequate, then
by end of 2004, define final design and write a technical proposal2005 go for procurementMarch ’06 install counters on the cryostatsApril ’06 commissioning, with the LVL1 trigger electronics
This project will be funded with ATLAS Common Fund resources as well as by US ATLAS
Project is proceeding with participation by:
Michigan State University (J. Huston is project leader)DubnaCERNUniversity of Texas-Arlington