1. Status of n-XYTER read-out chain at GSI
Rahul Arora
GSI, Darmstadt
GEM-TPC Meeting,18th November 2009

2. n-XYTER : Neutron- X, Y, Time, Energy Readout ASIC
Front-End:
128 channels
Front end for either polarity input signals
Charge sensitive pre-amp and peak detector
Time stamping with 1 ns LSB, 2ns resolution
Peak detection and analogue storage (10 bit electronic resolution)
Purely data driven, autonomous hit detection (self triggered)
Average per channel hit rate 160kHz with 10% dead time
(determined by pile-up on slow channel)
Readout:
Per channel analogue energy and digital time stamp FIFO (1ns resolution)
De-randomizing, sparcifying Token Ring readout at 32 MHz

3. Data Driven Front-End: Asynchronous Channel Trigger
Detection of Statistical, Poisson distributed signals
trigger timestamp reg.
comparator
Time Walk Compensation circuit
FAST shaper 18.5 ns
peaking
PDH
reset
charge preamp
dig. FIFO
charge input
SLOW shaper (2 stages)
140 ns peaking time
Peak detector &
hold,
free running
pulse height
output
analogue FIFO
Asynchronous registry and storage in 4-level fifo guarantees data loss < 4%
when read-out through token ring

4. n-XYTER Front End Topology

5. Power Consumption preamplifier 7.4 mW fast shaper 2.5 mW
slow shaper stage mW
slow shaper stage mW
discriminator mW
peak detector and hold mW
analogue FIFO mW
Overall we find about mW/channel
 air-cooling needed and installed for the tests

6. Experimental Built-in Safety-Belts with First Submission
Testability and Diagnostics
Individual analogue test channel
Built in test pulse generator
Programmable mask for every channel
Programmable, forced trigger of PDH for every channel (check signal pedestal)
Programmable dead time
Diagnostic counters for pile-up and token statistics
Backup Previsions / Safety
Every individual channel may be shut off
Clock signals derived on chip may be fed in separately
Time stamp clock may be reduced without change of readout clock
Various parts may be shut off
In addition to global threshold, bit programmable local threshold

7. N-XYTER FEB
Dimensions: 91 x 95 mm
8 layers
Revision C

8. Readout chain
The readout chain starts with the Revision C board having 50 micron silicon strip detector on it having detector capacity around pF.
The source for the detector is Am140
The next step is the ROC board connected to the FEB by flat cable.
The DC voltage supplied to the ROC and FEB is as follows
For ROC : Voltage - 5 V Current - 3 Amps
For FEB : Voltage - 5 V Current – 2.0 Amps
The versions of software and hardware used are
ROC hardware :
ROC software :
The ROC is communicated using ROCsoft software in a PC running linux.
The analysis is done using go4 sofware 4.3.1
The FEB is maintained at a constant temperature of 20 °C using air cooler.

9. Testing of one chip board
The pulse shapes are studied from the slow and fast
shaper using the oscilloscope.
The one chip board with silicon strip detector with pitch
of 50 micron is tested using Am140 .
The results are analyzed using go4 software.

10. Go4 plots for ADC count and channels
ADC count for all channels

11. Event signal with baseline subtraction and test pulse signal
noise
noise
Test Pulse
Am140

12. Overall status & Known bugs
Operational tests:
Full chain is operational
Drift with temperature, but if stabilized works for days
Dedicated tests (with developer)
Cross talk (?) may be present (mixed layout?)
Temperature dependency of E-output (work below 60 °C)

13. Outlook 2-chip board will be attacked as for as possible
Input to be changed to gas-detector
Data for the engineering run nearly complete
Submission foreseen before end of 2009