PHENIX RPC review

1
RPC Front End Electronics

• On chamber discriminator
• The strips
• The CMS discriminator chips
• The discriminator board
• Test results
• The TDC board
• The TDC and Crate block diagram
• The TDC board test result
• The trigger board
• The board counts
• Status

2
RPC Strip

• Our chamber is closely follow the CMS design. Our
  on-chamber electronics will try to follow their
  electronics too.
• The CMS barrel strips is 1.3m long, 4 cm or 2cm
  wide.
• 15/40 ohms impedance. 420pf/160pf capacitance.
• Fully terminated strips.
• CMS endcap RPC
• Cover 5/16 degree in phi, 7 to 38mm in width and
  22 to 55 cm in length
• Un-terminated.
• Lemo cables are used to connect strip to the
  discriminator board
• PHENIX RPC strip width range from 11.4 mm by
  141mm to 64.6 mm by 554.2mm.
• The smallest one has 46 ohms impedance and 16 pf
  of capacitance.
• The largest one has 10 ohms impedance and 286 pf
  of capacitance.

3
CMS RPC preamp/discriminator chip
Build on AMS 0.8 um BiCMOS process, 5V device.
15 ohms input impendence. 45mW/channel. 8
channels per chip. It is designed in Bari, Italy.
It has preamp, gain stage, zero crossing
discriminator, monostable (cover the dead time)
and LVDS driver. The chip is designed to deal
with 20 fC up to 20 pC with1.7fC ENC noise. Zero
crossing is necessary to deal with large dynamic
range. The time walk is about .6ns except for
very large charge. Testing show that threshold
level could be as high as 100fc without loosing
efficiency. All the chips has been fabricated.
Two wafers has been packaged and tested.
4
RPC 32 channel discriminator board
Cable adapter board
LVDS discriminator output
Serial download
32 channels per board Fused 6V input
analog/digital power supply .46A (use 5V, 3V
through low drop regulators) Serial download is
used to set 10 bits 4 channel threshold DAC (4mv
per bin) and Fire test pulse.
5
Connection diagram
Half octant Module edge
3M (Gray) 3432-5302
RPC TDC 64 ch
RPC disc 32 ch
3M (Gray) 3417-6640
Adapter Board
16 short RG174 cables
2-3 m cable ?
8 meters cable ?
3M N3432-L302RB
3M 6834-4500PL Or 8534-4500pl
3M 4640-7300
3M (gray) 3431-5302
2-3 m cable?
8 meter cable ?
Adapter Board
3M (Black) D89140-????
3M (Black) 3432-5302RB
Signal Cable 40 conductors twist flat ribbon
cable
3M 1700/40 Twisted Pair, Flat Cable, .050" 28 AWG
Stranded Fire rating VW-1
6
On board test pulse vs. threshold study
The discriminator is moving 4mv per step. The
test pulse is feed to the input amplify through
1pf cap. (not for calibration, functional check
only)
Channel 14 TDC distribution, DAC step 80
TDC
step
7
Direct pulse injection (threshold effect)
CMS Disc threshold
Channel 26
Channel 26
Channel 28
TDC
Channel 32
Channel 30
Channel 32
Threshold (8 mv per step)
TDC distribution at step 20 (160mv)
Test pulse is set around 4mv input
8
Direct Pulse Injection (fixed threshold)
Channel 45
Channel 46
Channel 44
TDC
disc. fired
Input (steps)
Inject test pulse through the cable adapter card
10pf capacitance (channel 45) 2mv per step,
160mv threshold (80fc) Cross talk seen at round
100mv.
9
DISC LVDS output at discriminator board
1.4V
DISC output after 10 meter cables
1.63V
69 ns time difference 1.61ns/ft ? 42 ft
Digitally subtracted pulse between and side
of discriminator LVDS output 500mv per division
Long output cable study
10
RPC TDC MODULE
Interface Chip Collects 64 Channel Of Data
L1 trigger primitives
TDC serial download
Trigger window
L1 trigger primitives
Event Data
32 channel digitizer
D I S C
Disc Serial download
LVDS Transmitter
MASK
Digitized Data
LVDS Receiver
Serial Download Timing etc.
L1 trigger etc
Event Data
44X BC
Test Pulse
Serial download
PLL
Test Pulse
44X BC
4x beam clock
11
TDC Module
TDC Use 44X beam crossing clock to digitized the
discriminated LVDS pulse, 2.5ns for 9.6MHz RHIC
clock Test Pulse Generated internally with the
FPGA with the same 44x beam crossing
clock Trigger Window The lower and upper limits
be can set channel by channel Mask Mask bits
can be set to turn off individual channel. Serial
data to Discriminator Board Control test pulse
firing and discriminator threshold ( chip by
chip)
The TDC Internal Test Pulse Scan
average TDC value
Sigma on the TDC
test pulse step
test pulse step
12
RPC FEM crate
L1 primitives
XMIT
T D C
T D C
Output To L1
Clock fanout
Clock Master
TDCs
Slow Control
GTM
DCM
L1
RPC(HBD) crate/BUS structure 6Ux160 mm VME size
13
RPC Trigger Board
Transceiver blocks
Arria FPGA De-serialized FEM data format
trigger data
Optical transmitter
2.8 Gbits/sec
Optical transmitter
Trigger data from FEM 1 pair of cable per FEM
RPC triggers is being designed. Schedule for
prototype around Sept. The module can receive up
to 6FEMs trigger data The optical trigger data
contains, idle, clock numbers and up to 12 16bits
FEM trigger data every beam crossing.
14
Channel count etc (one side)
Station 1ab 2 3 total
Channel 3072 3848 2872 9792
Channel per FEM (TDC) 64 64 64 65
FEM (TDC) 48 64 48 190
Disc Board 96 128 96 380
L1 trigger Fibers 8 16 8 32
FEM/ fibers 6 4 6
Support board/crate 3 4 3
FEM/crate 12 16 12
Crates 4 4 4 12
The crate size is like 6U VME crate. I would like
to limit the length discriminator cable to 10
meters. (to be tested about jitters) The RPC2,
3, we will need to find the crate space near the
detector. Crate need to be recess in the rack.
Cable routing space needed in front of the crate.

15
Channel count etc with RPC2/3 strips combined
(one side)
Station 1ab 2 3 total
Channel 3072 3848/2 2872/2
Channel per FEM (TDC) 64 64 64
FEM (TDC) 48 32 24 104
Disc Board 96 64 48 208
L1 trigger Fibers 8 16 8 32
FEM/ fibers 6 2 3
XMIT to DCM 4 5 4
L1 boards 8 8 4
FEM/crate 12 10 12
Crates 4 3 2
The crate size is like 6U VME crate. I would like
to limit the length discriminator cable to 10
meters. (to be tested about jitters) The RPC2,
3, we will need to find the crate space near the
detector. Crate need to be recess in the rack.
Cable routing space needed in front of the crate.

16
STATUS

• The discriminator and TDC modules has been
  successfully prototyped.
• Waiting for on chamber testing.
• Grounding issue need to be resolved with chamber
  testing
• CMS 32 channel board has been tested in both
  Colorado and BNL factory.
• We are building, 40 discriminator modules, 20 TDC
  boards, 3 sets of crates clock master modules
  for the coming run and individual factory
  readout/test stand.
• Trigger modules is being designed.