LHC CMS
Detector
Upgrade
Project
Design of the He and HB ODU
M. McKenna, M. Wayne
Notre Dame
1
LHC CMS
Detector
Upgrade
Project
●
Schedule Highlights
The ODU project is done in two stages
●
●
Preproduction of up to 32 ODUs (16 HB and 16 HE)
●
Mechanical unit design for HB/HE completed by 26-June-2014
●
Assembly of HE begins 28-July-2014, assembly of HB begins 25-Aug-2014
●
HE (HB) units at CERN and ready for mounting in RMs by 15-Feb-2015 (15-Mar-2015)
Full production of 360 ODUs (180 HB and 180 HE)
●
Design modifications based on test beam results completed by 04-Sep-2015
●
Assembly (done in 5 batches) of HE begins 28-Dec-2015, ends 18-May-2016
●
Last batch of HE checked out at CERN, ready to mount on 12-Sep-2016
●
Assembly (done in 5 batches) of HB begins 19-May-2016, ends 10-Oct-2016
●
Last batch of HB checked out at CERN, ready to mount on 8-Feb-2017
2
LHC CMS
Detector
Upgrade
Project
Initial design assumptions
●
●
Mechanical dimensions for both HE and HB ODU does not
change from 2011-2012 test beam designs
Patch panel, brackets, etc. are not changed, cookie design
accommodates different numbers of SiPMs on HE/HB and new
SiPM package dimensions
●
Threading of fiber pigtails changes accordingly
●
HE ODU will have 48 channels
●
●
●
Depth segmentation based on scheme developed by Vitaly Smirnov
HB ODU will have 64 channels
●
Depth segmentation based on 4 depth segments per tower
●
Interleaving of back two segments for some redundancy
Optical mixers – not sure if needed, would simplify design and
fabrication if these are not necessary (more on this later)
3
LHC CMS
Detector
Upgrade
Project
18
L-1
First prototype of the HE ODU
17
L0
18
L0
19
L0
20
L0
17
L1
18
L1
19
L1
20
L1
17
L2
18
L2
19
L2
20
L2
16
L3
17
L3
18
L3
19
L3
20
L3
16
L4
17
L4
18
L4
19
L4
20
L4
16
L5
17
L5
18
L5
19
L5
20
L5
16
L6
17
L6
18
L6
19
L6
20
L6
16
L7
17
L7
18
L7
19
L7
20
L7
16
L8
17
L8
18
L8
19
L8
20
L8
17
L9
18
L9
19
L9
20
L9
17
L10
18
L10
19
L10
20
L10
17
L11
18
L11
19
L11
20
L11
17
L12
18
L12
19
L12
20
L12
17
L13
18
L13
19
L13
20
L13
18
L14
19
L14
20
L14
18
L15
19
L15
20
L15
19
L16
20
L16
19
L17
20
L17
21
L0
22
21
L1
22
21
L2
22
21
L3
22
21
L4
22
21
L5
22
21
L6
22
21
L7
22
21
L8
22
21
L9
22
21
L10
22
21
L11
22
21
L12
22
21
L13
22
21
L14
22
21
L15
22
21
L16
22
21
L17
22
L0
23
L0
24
L0
25
L0
26
L0
27
L0
28
L0
29
L0
L1
23
L1
24
L1
25
L1
26
L1
27
L1
28
L1
29
L1
L2
23
L2
24
L2
25
L2
26
L2
27
L2
28
L2
29
L2
L3
23
L3
24
L3
25
L3
26
L3
27
L3
28
L3
29
L3
L4
23
L4
24
L4
25
L4
26
L4
27
L4
28
L4
29
L4
L5
23
L5
24
L5
25
L5
26
L5
27
L5
28
L5
L6
23
L6
24
L6
25
L6
26
L6
27
L6
28
L6
L7
23
L7
24
L7
25
L7
26
L7
27
L7
28
L7
L8
23
L8
24
L8
25
L8
26
L8
27
L8
28
L8
L9
23
L9
24
L9
25
L9
26
L9
27
L9
28
L9
L10
23
L10
24
L10
25
L10
26
L10
27
L10
28
L10
L11
23
L11
24
L11
25
L11
26
L11
27
L11
28
L11
L12
23
L12
24
L12
25
L12
26
L12
27
L12
28
L12
L13
23
L13
24
L13
25
L13
26
L13
27
L13
28
L13
L14
23
L14
24
L14
25
L14
26
L14
27
L14
28
L14
L15
23
L15
24
L15
25
L15
26
L15
27
L15
28
L15
L16
23
L16
24
L16
25
L16
26
L16
27
L16
28
L16
L17
23
L17
24
L17
25
L17
26
L17
27
L17
28
L17
Eta
16
Eta
5° 16
5°
1.305
17
5° 17
5°
1.392
18
5° 18
5°
1.479
19
5° 19
5°
1.566
20
5° 20
5°
1.653
Eta
21
10°
1.740
22
10°
1.830
23
10°
1.930
24
10°
2.043
25
10°
2.172
26
10°
2.322
27
10°
2.500
28
10°
2.650
29
10°
2.868
Up to 7 layers in
depth
96 channels for
each pair of ODU
3.000
Depth1
Depth2
Depth3
Depth4
Depth5
Depth6
Depth7
Threading a bit tricky but achievable
With drawings and color-coding, can
be done in “mass production” by
students and techs
But there are a few issues to resolve
4
LHC CMS
Detector
Upgrade
Project
HE ODU design issues
●
●
●
With the current design for depth segmentation, one ODU of each
pair requires 49 SiPMs while the other requires 47 SiPMs
●
Consequence of how cables bring in the fibers to the patch panels
●
We propose combining L-1 with L0,L1,L2 in tower 18 - open to other suggestions
●
Will result in 2 unused SiPM channels per pair of HE ODU
The patch panel has a connector for “Layer 00”
●
Second sigma loop in the 0th layer (?)
●
Not clear if these fibers are actually brought to the ODU – eliminate?
●
We propose threading fibers from Layer 00 together with Layer 0
●
There is no input for tower 17, L0 – we will use L00 instead
In 44 of the 48 channels the SiPM receives 4 fibers or less (2.8 mm
device), the other 4 channels receive 5-7 fibers (3.3 mm device)
vs
vs
We propose this
5
LHC CMS
Detector
Upgrade
Project
Other HE ODU points, questions
●
●
●
The “cookie” will have 44 holes with 2.37 mm diameter (for 2,3,4
fibers) and 4 holes with 2.87 mm diameter (for 6,7 fibers)
The holes for attaching the patch plate and bottom plate to the
cookie holder have been moved to provide increased clearance
for a v-groove needed for the polishing fixture
Calibration inputs
●
We propose 7 calibration channels with 8 fibers per channel
●
Calibration fibers are 0.25 mm clear PMMA, one fiber to each SiPM with 8 extra fibers
●
Will springs be used to press the cookie to the SiPMs?
●
Will black anodizing be required?
●
●
If “yes” we need to know which areas to keep clear for electrical ground contact
There are unused connector slots – do we need blank connectors
to cover them up?
6
LHC CMS
Detector
Upgrade
Project
Optical Mixers
Optical mixers are designed to spread
large amounts of light across the SiPM
active area
Effectively increases the dynamic range at
the high end, but fast recovery time can
also increase the dynamic range
Do we need the mixers for HE and/or HB?
We propose instrumenting half the
preproduction ODU with mixers, test in the
beam and on the bench, then make the
final decision for full production
Optical Mixer plate
4 mm thick – 3.2 mm diameter fiber
elements
Note: overall design must account for
additional thickness of mixer plate
7
LHC CMS
Detector
Upgrade
Project
HB ODU Design issues
●
To our knowledge, no real study of the depth segmentation has
been done yet – only design is the following:
4 segments in depth per tower
Identical for towers 1-15, tower 16
a bit different
Interleaving of back two segments,
then combined in the electronics
ODUs will require 64 SiPM each –
32 small, 32 large diameter
Threading looks to be challenging
because of the interleaving
8
LHC CMS
Detector
Upgrade
Project
HB ODU – 1st attempts at threading
This is doable but fibers are tight once the ODU is compacted to
appropriate size
The threading above was done using the same “hybrid” package
as in the HE ODU
Might be easier with 4 packages with all smaller diameter, 4 with
all larger diameter
9