1. New Ideas on long-term DCT upgrade: conceptual design for DOCAZ
Ted Liu (Fermilab,
Related material can be found:
For DOCAD: see
For BLTz: see
This talk contains some more details on what I have talked about
at the end of the first upgrade meeting on July 5th.
Ted Liu, July 18,00, idea on Ztrigger

2. Ted Liu, July 18,00, idea on Ztrigger
What kind of background
we are dealing with? B1
HER
LER
Lost particle interact
with beampipe flange
real collision
due to a step in the
synchrotron mask
Track z distribution
for L1 passthrough
events
Ted Liu, July 18,00, idea on Ztrigger

3. The Drift Chamber ( DCH )
L1 Long term strategy:
cut in Z using TSF fine position info from stereo superlayers
Cell size:
1.2 cm x 1.8 cm
The Drift Chamber ( DCH )
10 superlayers of 4 layers each
Axial and stereo alternate
Ted Liu, July 18,00, idea on Ztrigger

4. Ted Liu, July 18,00, idea on Ztrigger
L1 long-term strategy:
Can we cut in Z using TSF position info from stereo SLs?
Stereo SLs --> Z
Axial SLs --> DOCA
DOCAZD
Close to IP in z
Cosmic ray events
Off IP in z
Ted Liu, July 18,00, idea on Ztrigger

5. Ted Liu, July 18,00, idea on Ztrigger
What has been discussed in the past:
Long ago, Anders Ryd and I talked about one possible hardware implementation using a large( or huge) LUT approach in r-phi view. In other words: move some L3 DCH algorithm upstream to L1.
Curent L3 first stage DCH
Track finding algorithm involves
slicing in phi in 120 bins. Without
track fitting, z resolution is
rather poor. Hardly surprising
as each bin size is on the
order of ~ few cm even for
the inner most SLs (TSF fine
phi resolution ~ 1 mm).
To make more slices (> x10),
could involve huge LUTs …
Ted Liu, July 18,00, idea on Ztrigger
L3 Event Display
Here is an new (simpler) idea …
next

6. Ted Liu, July 18,00, idea on Ztrigger
Use the simple fact: tracks are straight lines projected in r-z plane
r-z view
r-phi view
Ted Liu, July 18,00, idea on Ztrigger

7. Ted Liu, July 18,00, idea on Ztrigger
Basic idea (have many slices in theta)
Off Z track
40~50 or so slices in theta
~ 2 cm in z for SL2
TSF phi resolution ~ 1 mm
Z resolution ~ 2 cm
Ted Liu, July 18,00, idea on Ztrigger

8. Ted Liu, July 18,00, idea on Ztrigger
Simplest case: high Pt tracks
Use Axial&Stereo SL segments fine phi to calculate z: total 6 points
 slices x
A10 x U9 x U8 x A7
Convert phi separation into z separation x V6 x U5
tracks from IP will
leave hits in one  slice,
tracks off IP in z will
leave hits in many  slices x A4
Z (i) track finding algorithm:
for ith  slice,  hits >= 4 (out of 6) x V3 x U2
(same idea as in DOCAD) x A1
Ted Liu, July 18,00, idea on Ztrigger
programmable
Could even try weighted (by resolution) sum

9. Ted Liu, July 18,00, idea on Ztrigger
when low Pt tracks involved: need corrections (Pt dependent)
for example:
phi separation for A1&U2:
 = 2 - 1c, not 2 - 1
A10 seed x
A10
then convert  into Z A7
this is because  is wrt
the pivot cell for each SL 2 A4
1c x
if  is wrt the
top and bottom
cells, may not need
corrections. but too
much change in TSF? x U2 A1 1
this can be naturally done in Pt slices:
i.e. in DOCAD  what is DOCAD?
Ted Liu, July 18,00, idea on Ztrigger

10. Ted Liu, July 18,00, idea on Ztrigger
Current PTD algorithm
New DOCAD algorithm
(baseline design: simple algo.)
A10 seed x x
Pt threshold (800MeV)
Pt slices
SL7
SL7 … …
SL4
SL4
SL1
SL1 x x IP IP
Tracks (above threshold) coming from IP
should leave all the hits in one of the slices
4 hits on one track with ~1mm,
should be able to tell whether the
track is from IP
Tracks not coming from IP will most likely
leave hits in different slices
Ted Liu, July 18,00, idea on Ztrigger
for details on DOCAD, see

11. Ted Liu, July 18,00, idea on Ztrigger
Thus a possible DOCAZD algorithm could be:
For each seed (as in current PTD):
use DOCAD algorithm locate axial SL hits for each Pt slice
for a given axial SL hit in a given Pt slice, look for nearby
U or V SL hits in a certain range (max range&sign is SL dependent)
(3) apply the correction in  to get 
(4) convert  into Z
(5) then in r-z plane, for each  slice, apply z track finding
algorithm:  hits >= 4 (out of 6)
Note: as in PTD, DOCAZD seeds can be in SL10 or SL7.
if one axial SL hit is missing, the correction can
still be made for each Pt slice
DOCAZ requires a track coming from IP in both x-y & z view
Ted Liu, July 18,00, idea on Ztrigger
Each board should receive enough neighbor data to cover low Pt tracks (at least ~200 MeV)

12. Ted Liu, July 18,00, idea on Ztrigger
Drift Chamber
One possible scenario
keep BLT path
the same (many
advantages!)
All track
segments
found
Trigger data
Supercell
hits
24 Gbits/s
B &/or A
GLT
Fine phi info
for all SLs
DOCA&Z?
DOCAD
in r- plane
Axial SLs
 -> Z
DOCAZD
X 16 ?
Z track
finding
in r-z plane
Stereo SLs
Ted Liu, July 18,00, idea on Ztrigger
Track Segment Finder (x24)

13. Ted Liu, July 18,00, idea on Ztrigger
Basic DOCAZ engine unit (for a given seed):
3D problem  2d problem in r-z & r-phi planes
a given seed 9 x 8 x 6 x … 5 …. x
in r-phi plane … 3 x 2 x
project into r-z plane IP
If no GLT modification:
Z(i) can be ORed to give one Z for a given seed, then
converted into 16 bits phi map (passed to GLT , as in A’)
Or only keep B from BLT, and have DOCA and Z output to GLT.
Ted Liu, July 18,00, idea on Ztrigger
detailed information saved in trigger DAQ data

14. Ted Liu, July 18,00, idea on Ztrigger
Basic DOCAZ engine unit: possible improvement (1)
a given seed 9 x 8 x 6 x … 5 …. x ….
in r-phi plane … 3 x 2 x IP
project into r-z plane
Overlapping slices in both r-z and r-phi planes
(only shown in r-z plane)
Ted Liu, July 18,00, idea on Ztrigger

15. Ted Liu, July 18,00, idea on Ztrigger
Basic DOCAZ engine unit: possible improvement (2)
a given seed 9 x 8 x 6 x … 5 …. x ….
in r-phi plane … 3 x 2 x IP
project into r-z plane
finer slices in outer SLs (take advantage of the ~2cm Z resolution)
outer good SL hits may provide enough constraint in z
Ted Liu, July 18,00, idea on Ztrigger
Prefer configurable
for robustness

16. Ted Liu, July 18,00, idea on Ztrigger
This is just a conceptual design
Probably a good starting point, but needs lots of studies:
How many slices in r-z and r-phi planes?
What’s the lower limit in Pt? Can we go below
200 MeV? (limited by hardware?)
(3) Impact on physics? (tau & 2-photon)
Very high multiplicity B decays will likely only have low Pt tracks,
define >= 4 A&B trigger line to save these events, no requirement
on DOCAZ? How much can be save this way? How much bkg?
(4) how much background can be rejected?
(5) Performance vs Chamber cell ineff.? Robustness?
(6) Performance vs high background (occupancy)?
(7) Hardware implementation details…
The devil is in the details. But most of them (if not all)
can be studied with existing TSF data! Well defined problems…
Ted Liu, July 18,00, idea on Ztrigger
CAREFUL calibration of TSF LUTs is very important!

17. Ted Liu, July 18,00, idea on Ztrigger
L1 long-term strategy:
(a slide from my previous talk, Oct. 99)
Can we cut in Z using TSF position info from stereo SLs?
Stereo SLs --> Z
Axial SLs --> DOCA
DOCAZD
Current
“trigger
volume”
Possible improved “trigger volume”??
What to expect? The answer is in the TSF data we already have!
Ted Liu, July 18,00, idea on Ztrigger

18. Ted Liu, July 18,00, idea on Ztrigger
Other related issues:
Drift Chamber
How to bring the fine phi information for
stereo SLs? First look at how current TSF
pass the information to downstream (BLT&PTD).
TSF engine
for axial SLs To
backplane
hits from
axial layers
Trigger data
24 Gbits/s
PTD data
formatter
16 bits
@clk30
Input formatters
what’s missing
BLT data
formatter
4 bits
@clk30
hits from
stereo layers
TSF engine
for
Stereo layers
Ted Liu, July 18,00, idea on Ztrigger
Track Segment Finder (x24)

19. Ted Liu, July 18,00, idea on Ztrigger
Drift Chamber
If we remake all TSFs, then it is straight forward:
add traces from TSF stereo engine FPGA to PTD
formatter FPGA(use bigger component, more pins),
and use more pins on backplane
TSF engine
for axial SLs To
backplane
hits from
axial layers
Trigger data
24 Gbits/s
PTD data
formatter
16 bits
@clk30
Input formatters
Add traces
BLT data
formatter
4 bits
@clk30
hits from
stereo layers
TSF engine
for
Stereo layers
Pros: well defined simple hardware modifications
Cons: have to remake all TSFs
Ted Liu, July 18,00, idea on Ztrigger
Track Segment Finder (x24)

20. Ted Liu, July 18,00, idea on Ztrigger
Drift Chamber
If we DON”T remake all TSFs, then life is more complicated:
One possibility (as I mentioned long ago) is to give up some
fine phi info for axial SLs and pass fine phi info for stereo layers.
This can be done in Input Formatters (VHDL code change).
TSF engine VHDL code needs some modification as well.
TSF engine
for axial SLs To
backplane
hits from
stereo layers
Trigger data
24 Gbits/s
PTD data
formatter
16 bits
@clk30
Input formatters
BLT data
formatter
4 bits
@clk30
hits from
axial layers
TSF engine
for
Stereo layers
Pros: can use all existing TSF hardware
Cons: need new simpler algorithm, performance issues? Uncertainties….
Ted Liu, July 18,00, idea on Ztrigger
Track Segment Finder (x24)

21. Ted Liu, July 18,00, idea on Ztrigger
A possible simpler algorithm: with only stereo SL fine phi info available
This means no more DOCAD,
but one can try to improve the
current BLTz algorithm.
With much finer information
on SL2&3, one should be able to
do much (?) better than current BLTz.
Maybe outer stereo SLs fine phi info
can also be helpful.
Close to IP in z
Cosmic ray events
use SL2&3 separation in fine phi
I haven’t thought much
along this line, need more
investigation…
Off IP in z
Ted Liu, July 18,00, idea on Ztrigger
For details on BLTz, see

22. Ted Liu, July 18,00, idea on Ztrigger
Summary of what I have said
a new algorithm for a possible DOCAZ,
assuming fine phi information for all SLs are available
to the DOCAZ boards;
(2) one possible way to modify TSF hardware
to make fine phi information available for all SLs
(3) Some thoughts on a possible simpler algorithm
(improved BLTz) …
Personal view: (1) + (2) is most promising
Note: I came up with the idea (1) shown here on 4th of July while watching fireworks. Since then I have been busy with moving, so by no means this is a detailed design. Just some random thoughts in a few hours. Hopefully you will find them useful… I wish I had the time to do the TSF data analysis to finalize the new algorithm, but I am now paid to do other things….. I will be more than happy to help if someone is willing to give a try…
Ted Liu, July 18,00, idea on Ztrigger

23. Ted Liu, July 18,00, idea on Ztrigger
Drift Chamber
One possible scenario
DAQ
Level 3 Filter
DAQ
All track
segments
found
Trigger data
24 Gbits/s
A,B
Supercell
hits
GLT
DZ?
Fine phi info
for all(?) SLs
DOCAZD ??
Ted Liu, July 18,00, idea on Ztrigger
Track Segment Finder (x24)

24. Ted Liu, July 18,00, idea on Ztrigger
LER
Ted Liu, July 18,00, idea on Ztrigger
HER

25. Ted Liu, July 18,00, idea on Ztrigger
Drift Chamber
Upon a L1 Accept ...
DAQ
Using segments found by TSFs as
seeds, fast algorithm applied to DCH
data to further reject background...
reduce the rate from 2 kHz to 100 hz.
Level 3 Filter
DAQ
Trigger data
Track
segments
found
24 Gbits/s
Ted Liu, July 18,00, idea on Ztrigger
L3 Event Display
Track Segment Finder (x24)

26. Ted Liu, July 18,00, idea on Ztrigger

27. Ted Liu, July 18,00, idea on Ztrigger

28. The Drift Chamber ( DCH )
10 superlayers of 4 layers each
Axial and stereo alternate
Ted Liu, July 18,00, idea on Ztrigger

29. Ted Liu, July 18,00, idea on Ztrigger
Trigger Line Definition/Convention
DCT Objects:
B: short track reaching SL5, Pt ~120 MeV
A: long track reaching SL10, Pt ~180 MeV
A’: high Pt track reaching SL10, Pt > 800 MeV
EMT Objects:
M: minimal ionizing cluster, E >100 MeV
G: intermediate energy cluster, E >300 MeV
E: high energy cluster, E >700 MeV
Y: backward barrel cluster, E >1 GeV
IFT Objects:
1U: 1 high P muon in backward endcap o
B*,M*...* means back-to-back objects(>120 )
D2 = 2B&1A, D2* = B*&1A
D2*+ = B*&1A&1A’ , A+ = A&A’
Ted Liu, July 18,00, idea on Ztrigger

30. Ted Liu, July 18,00, idea on Ztrigger
Drift Chamber
Upon a L1 Accept ...
DAQ
Using segments found by TSFs as
seeds, fast algorithm applied to DCH
data to further reject background...
reduce the rate from 2 kHz to 100 hz.
Level 3 Filter
DAQ
Fine position
info for
segments
found for all
superlayers
Trigger data
24 Gbits/s
Currently TSF provides fine position info
for all SuperLayers to L3, only axial SLs
info passed to PTD.
Ted Liu, July 18,00, idea on Ztrigger
Track Segment Finder (x24)

31. Ted Liu, July 18,00, idea on Ztrigger
Trigger Lines for Hadronic Events
run9304
Requirements:
B Physics
Pure DCT
CP Channels: high eff.
Non-CP channels:
high + precise eff.
DCT + EMT
Continuum
High & precise eff.
for background sub.
Pure EMT
Strategy for eff. Measurements:
orthogonal lines
redundant lines
record all trigger DAQ data
prescaled lines
Ted Liu, July 18,00, idea on Ztrigger

32. Ted Liu, July 18,00, idea on Ztrigger
Use orthogonal DCT-EMT lines to study eff.
From Su Dong
Total eff for hadron skim: (EMT OR DCT) > 99.3%
Ted Liu, July 18,00, idea on Ztrigger

33. Ted Liu, July 18,00, idea on Ztrigger
run9304
Trigger Lines for non-physics Events
Requirements:
Luminosity, calibration:
2-prong ee,
High + precise eff.
Pure DCT
Calibration, beam monitor:
1-prong ee,
DCT + EMT
 only
Pure EMT
Background monitoring
Background&Trigger studies
Ted Liu, July 18,00, idea on Ztrigger

34. Ted Liu, July 18,00, idea on Ztrigger
Trigger Lines for  and 2 Events
Requirements:
 Physics
Pure DCT
Rare & Asy.: high eff.
Branch Ratios:
precise eff.
DCT + EMT
2 Physics
precise eff.
Pure EMT
Shortcomings:
All unprescaled lines have high Pt
cut (800MeV) and with back-to-back
requirement. No unprescaled orthogonal lines.
All high eff. Lines have to be prescaled.
high background rate, will try to improve…
add 2BM+1AM, lower Pt cut?
Ted Liu, July 18,00, idea on Ztrigger

35. Ted Liu, July 18,00, idea on Ztrigger
L1 Strategy to improve performance
Better Combination of trigger lines:
DCT+EMT phi matching
Give up some orthogonal lines
...
Improve trigger objects:
Short-term: PTD ---> DOCAD
Long-term: DOCAD --> DOCAZD?
Need good understanding of
background --> next
Ted Liu, July 18,00, idea on Ztrigger

36. Ted Liu, July 18,00, idea on Ztrigger
LER
HER
Single beam
LER
HER
L1 pass thr.
events
Z distribution
From S. Petrak
Ted Liu, July 18,00, idea on Ztrigger

37. Ted Liu, July 18,00, idea on Ztrigger
LER
HER
LER
HER
Single beam
L1 pass thr.
events
x-z view
Ted Liu, July 18,00, idea on Ztrigger
Many tracks from beampipe: off Z --> off IP in x-y

38. Ted Liu, July 18,00, idea on Ztrigger
Drift Chamber
DCT Trigger Hardware
Binary Track Linker (BLT x1)
Coarse data
for all
supercell
hits
Trigger data
24 Gbits/s
A, B 16
GLT 16 A’
Fine position
data for
segments
found for
axial SLs
PT Discriminator
PTD (x8)
New idea
Ted Liu, July 18,00, idea on Ztrigger
DOCAD
Track Segment Finder (x24)
(only firmware change)

39. Ted Liu, July 18,00, idea on Ztrigger
Drift Chamber Trigger ( DCT )
The heart of DCT is the Track Segment Finder
TSF continuously live image processor
A novel method: using both occupancy
and drift-time information, to find track
segments continuously with:
time resolution of ~ 100 ns,
event-time jitter window ~ 100 ns
spatial resolution ~ 1 mm
used for track Pt Discrimination
(1) send segment patterns downstream for
L1 trigger decision making
Upon a L1 accept:
(2) send segment patterns to the DAQ
system for use in Level 3 ...
Track Segment Finder
Ted Liu, July 18,00, idea on Ztrigger
Use 24 TSF modules

40. Ted Liu, July 18,00, idea on Ztrigger

41. Ted Liu, July 18,00, idea on Ztrigger

42. Ted Liu, July 18,00, idea on Ztrigger
Current PTD algorithm
New DOCAD algorithm
(baseline design: simple algo.)
A10 seed x x
800MeV
Pt threshold (800MeV)
850MeV
SL7
900MeV
SL7
1 GeV
SL4
SL4
SL1
SL1 x x IP IP
4 hits on one track with ~1mm,
should be able to tell whether the
track is from IP
Tracks (above threshold) coming from IP
should leave all the hits in one of the slices
Tracks not coming from IP will most likely
leave hits in different slices
Ted Liu, July 18,00, idea on Ztrigger

43. Ted Liu, July 18,00, idea on Ztrigger
Apply DOCAD algorithm to TSF data
Hadron skim: signal
Effect on Signal:
PTD on
Use hadron skim (~10% bkg)
~ 4% loss at turn on
DOCAD on
Effect on Background:
Use single beam run
L1 pass thr events
Max Pt in the event
40% rejection on A’ line
with simple algorithm
PTD on
Background rejection: 40%
The goal here is not to find the
best algorithm possible, but one
which is easy to be implemented
and with good performance
DOCAD on
Ted Liu, July 18,00, idea on Ztrigger
LER single beam run: background

44. Ted Liu, July 18,00, idea on Ztrigger
Require
3/3 in ALL slices
DOCAD algorithm: possible improvement
TSF can determine segment
location with 1 mm resolution
only for 4/4 patterns
But 20% signal loss
The resolution is degraded
for 3/4 patterns:
Due to cell ineff.  1 2 x x x x x = x x + x x x x
3/4
4/4
4/4
1 <  < 2
calibrating 3/4 patterns should help
70% bkg rejection!
using the  information should help
(baseline design ignored )
Ted Liu, July 18,00, idea on Ztrigger
Currently 3/4 pattern LUT is derived from 4/4 patterns