OT @ 2 x 1033
Marcel Merk
(for the OT group)
Simulations: Jan Amoraal
LHCb Upgrade Workshop
Edinburg, January 11-12
# interactions vs Lumi
Particle Flux (MB events)
Lumi 2 x 1032
16 000
Lumi 20 x 1032
160 000
Current in wires (MB events)
Lumi 2 x 1032
I < 5 nA/cm
Lumi 20 x 1032
I < 50 nA/cm
Irradiation Studies @ high intensity
(X-ray tube Heidelberg)
However: Irradiation studies with production
modules show gain reduction at low intensity.
=> Outgassing effect?
20 x 1032: in hottest area:
Current = 50 nA/cm
=> 0.5 C/cm/year (1 y = 107 s)
Channel
accumulated charge
≈1.3 C/cm
No effects seen
Pos (cm)
B events: Toy Model for OT spillover
BX
Gate:
-2
-1
0
+1
+2
Assume: maximal drift time ~65 nsec (=> 2.5 BX)
In this case: 1/5 of BX-2, 3/5 of BX-1, BX0, 3/5 of BX+1, 1/5 of BX+2
• For a MB event we see 1 Nint pile-up + 1.6 Nint spill-over = 2.6 Nint interactions
• For a B event we see 1 B + 2.6 Nint interactions
Assume further:
• A minimum bias interaction produces on average ~ 20 tracks
• A “B” interaction produces on average ~ 40 tracks
Examples: <N int>
0.6
(2 x 1032)
# tracks (MB-event)
#tracks (B-event)
31
71
3
(10 x
1032)
156
196
6
(20 x 1032)
312
352
Ratio: hi:lo
352:71 = ~5
Deposits Time Spectrum (B events)
The multi bunch structure leads to the typical TDC spectrum for the deposits:
Lumi 2 x 1032
Lumi 20 x 1032
1 B + 0.6 pile-up + 1 spill-over :
long timeof-flight tail
-2
-1
0
+1
+2
1 B + 6 pile-up + 10 spill-over :
Hit Efficiency
The probability that an MC hit (ie. A particle passing the OT layer) leads to
at least one hit in a double layer.
Lumi 2 x 1032
Lumi 20 x 1032
=> No large detector/readout inefficiency for high luminosity
OT Times distribution
The number of registered OT times in a B event
Lumi 2 x 1032
Typically 3000 hits
10000 OT-times
Lumi 20 x 1032
Typically 14000 hits
10000 OT-times
OTTimes: MC information
Lumi 2 x 1032
Lumi 20 x 1032
• 497 evts B2Jpsi(mumu)Ks
(Boole v12r10)
• 490 evts B2Jpsi(mumu)Ks
(Boole v12r10)
• 3336 OTTimes per evt
(Avg. occ 6%)
• 13647 OTTimes per evt
(Avg. occ 25%)
– Evt
•
•
•
(/) Spill 64%
Primary 41%
Secondary 23%
Unknown 0.25%
– Evt
•
•
•
(/) Spill 37%
Primary 23%
Secondary 13%
Unknown 0.1%
– Spill over 29%
• 12% Next + 11% Prev +
7% (PrevPrev+NextNext)
– Spill over 57%
• 23% Next + 22% Prev +
12% (PrevPrev+NextNext)
– Noise 7% (5% X-talk (input))
– Noise 6% (5% X-talk (input))
Occupancy per layer
The average occupancy for each layer (x,u,v,x) in T1, T2, T3
Lumi 2 x 1032
T1
T2
Lumi 20 x 1032
T3
~6% occupancy
T1
T2
~26% occupancy
Ratio is ~ 1 to 4-5 compatible with the toy model
Expect Occupancy @ 10 x 1032 ~ 15%
T3
Occupancy vs X-coordinate
Lumi 2 x 1032
Lumi 20 x 1032
40% occup
10% occup
“Guesstimated” curve for 10 x 1032
• In current geometry the occupancy does not reduce fast as function of x position
• 20 x 1032 : Occup up to 40% seems unrealistic with current detector geometry
⇒ Use shorter OT modules or different technology?
• 10 x 1032 : Will it be possible to operate with occup up to 25%??
Considerations for 20 x 1032
• Radiation tolerance (Minimum bias)
– Hard to predict ageing effect
– OT technology designed for 5 x 1032
– High intensity radiation tolerance tested up to 1.3 C/cm
• Equivalent to 10 years @ 5 x 1032 or 2.5 years @ 20 x 1032
• Occupancy (B events)
– Occupancy a factor of 5 higher as in 2 x 1032
– Need to reduce occupancy to keep pattern recognition
task comparable to current situation
• Shorter OT modules by ~ 30 cm
(ie a larger IT) might be a possibility…
Current OT modular layout
S1
Module Type F
S2
S3
OT straw geometry for 20 x 1032?
150
100
200
A new OT detector!
40
IT surface
~3 m2 /layer
Such a geometry reduces the irradiation and the occupancy in the
OT detector
to be
withneeded?
the design of the current detector.
About 3-4
m2compatible
inner tracker
Questions from Ueli/Leo (1)
•
What is needed (replacements, upgrade) to be able to sustain 2*10**33
luminosity during 5 years concerning both electronics and mechanics (rates,
occupancies, radiation damage)?
¾ Not changing the OT geometry seems to give too high rates/occupancies.
¾ OT TDR: cost OT modules: 2720 kCHF
•
What are the estimates of the detorioration on the physics measurement
(e.g. track reconstruction, energy cluster reconstruction, electron
identification) due to higher occupancies?
¾ See before: Pattern recognition with 40% occupancy seems unreasonable.
A test running Brunel at high lumi with current geometry took forever…
•
What if the readout is performed at:
– 40 MHz
– 1 MHz with a factor 40 more front-end storage
¾ The OTIS can output 1 byte/25 nsec. 40 MHz requires a redesign.
¾ OT TDR: cost electronics 5570 kCHF.
• Who can be seen as contact person for the upgrade?
¾ Antonio Pellegrino
• Who can give the requested talk at the workshop?
¾ Anyone.
Questions from Ueli/Leo (2)
• Which groups are interested in an upgrade, with
which manpower (and related money)?
¾ In current OT community:
¾ Need to get experience with current OT detector
performance to estimate possibility with straw
technology at high lumi.
¾ No money/manpower available today for large
investments.
¾ My Personal Opinion:
¾ Before considering a new OT detector strong
indications for new/exciting physics must be seen.
End
Hit Flux
2 x 1032
OTTimes per layer
Lumi 2
Lumi 20
Calibrated time spectrum
Lumi 2
Lumi 20
TDC spectrum