What we have learned from UTOPIA so far?
• Defined a set of gauge histos to compare layouts
•Exercised on barrel-part only and proved 4 Pixel layers better
than 3
• verified good reconstruction efficiency (barrel only) up to 400
pile-up requiring >10 clusters
• compared Pixel and Strips based on cost& power & X0
• cost and power and X0 of short strips not much higher than long
strips  extend their use to larger radius
• cost and power and X0 of Pixel allows to use them up to a radius
of ~25cm (if justified by simulation/physics)
• radiation damage and lifetime
• must consider part at r<10cm as removable
• cooling
• the cooler the better (<-25C on sensor)
•extension to end-cap coverage
• only started...
28-1-2010
Leonardo Rossi
INFN Genova - UTOPIA #12
0
What we have learned ...
• B-layer
• short (200mm) Pixel is a good move, but slightly harmful in barrel
for h>1.5  must consider short b-layer(s)
• B-layer is critical for impact-parameter physics  must consider
double b-layer to have a fall back in case of inefficiencies.
• Track trigger
• true L1 trigger impossible for HW and bandwidth limitations
•lot of effort went into the implementation of a layout
which was This tool, together with the above results, will be the legacy of UTOPIA
•Easy to modify
•Including a detailed description of services (also easy to scale with
layout changes)
• in the mainstream of the ATLAS Athena simulation.
•With full rapidity coverage
• We have still few questions to address to close out, but
real
data have arrived
and
have
changed.
Leonardo Rossi
INFNpriorities
Genova - UTOPIA
#12
28-1-2010
1
Issues to conclude the UTOPIA mandate
The comparison between alternative solutions should be based primarily on track efficiency, fake rate, impact parameter
resolution (along r-phi and z), momentum resolution (all parameters vs eta, pt, particle type, pile-up, within jets). B-tagging can
be considered later if time allows.
Issues to be addressed to conclude the UTOPIA task force mandate:
+ impact of lumi levelling (simpler layout?)
1)
Do we have a better layout with a 5th Pixel layer?  compare 5P+4S layout with 4P+5S (both on barrel and end-cap)
2)
Should we have the same number of hits in barrel and end-cap?  compare performance in barrel and in end-cap (including
service material)
3)
Do we have a better layout with all short strip detectors?  compare standard layout and all-short-strip layout (emphasis
on jets and high pile-up)
4)
Rapidity gap width around eta=1 vs momentum resolution  compare performance if 11 (or 10) hits are required in barrel,
transition and end-cap.
5)
Is full coverage a must?  compare performance with gaps (along z) between modules and no gap. Evaluate implication of
absence of overlap for the alignment procedure.
6)
How critical is the module tilt angle (Lorentz angle compensation)? Important for engineering simplification  compare
same layout with 0, 10 and 15 degrees tilt
7)
Robustness 1  compare 98%, 95% and 90% efficiency in a given layout
8)
Robustness 2  compare layout w/nominal Rad. and Int. length per layer (X0,L), with same having 0.8(X0,L) and 1.5(X0,L).
9)
Optimization of Pixel layout at high eta (long cluster problem)  compare high-eta impact parameter resolution with same
at eta~0.
10) Impact of fast track trigger on layout  material and bandwidth needs (plus impact on reconstruction strategy in case of
doublets of “close layers”).
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Leonardo Rossi INFN Genova - UTOPIA #12
28-1-2010
To discuss
• To still afford the remaining issues we need:
• to find the right manpower able to commit
•The manpower situation for UTOPIA may only
become worse in the near future as we are already
the follower in the LHC competition
• either we do the work over the next month or we can
forget it for a while
• this the focal point of the discussion
•... or just write a report with what we got so far
and leave to some future body our legacy?
We have been dealing with a (fast) moving target and we have to wrap-up in any
case here. This effort will be resumed when the sLHC plan will be known better.
28-1-2010
Leonardo Rossi
INFN Genova - UTOPIA #12
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