n-XYTER for diamond detectors - GSI · nXYTER chip. Simulation model doesn't match exactly to...

NoRHDia Workshop 2008, GSI Darmstadt, June 10th 2008

n-XYTER for diamond detectors

Rafał [email protected]

UST-AGH Cracow, GSI Darmstadt

mailto:[email protected]


Contents

(1) Introduction to nXYTER

(2) Overview of requirements for diamond detector

(3) Simulations

(4) Conclusions and possible future developments


n-XYTER: The DETNI Neutron Detector Readout ASIC

Neutron – X, Y, Time and Energy ... RFrontEnd: 128 channels Ready for different popular input signals Charge sensitive preamp and peak detector Time stamping with 1ns LSB and 2ns resolution Peak detection and analogue storage (10 bit electronic storage) Purely data driven, autonomous hit detection (self triggered) Average per channel hit rate 160 kHz with 10% dead time

(determined by pile up on slow channel)

Readout: Per channel analogue energy and digital timestamp FIFO (1ns res.) Derandomizing, specifying Token Ring readout at 32 MHz


Input side of nXYTERWire connectionsshould be well definedbefore tests.

Photo: U. Trunk


n-XYTER architecture


Analogue Signal Sequence (Test channel)

Trigger pulse

Slow channel

Fast channel

Comparator output

It really works!


General Purpose

nXYTER is designed to use for neutronmeasurements, but also can be used with:➔ Silicon strip detectors (STS)➔ Gas detectors (GEMTPC)➔ Other applications

Do we can use nXYTER forSingle and PolyCrystal Diamond Detectors?

Lets investigate it!


Questions and input data

NXYTER is designed for 30 pF input (detector) capacitance. DD give us the order of 1 pF.

Questions are:

➔ signal response for so low capacitance

➔ noise

➔ Discrimination Time and TimeWalk

Tested DD has pixel configuration and 5x5 mm of total area (3 pF):

➔ 9 pixels 1.67x1.67 mm, 0.33 pF each pixel➔ 16 pixels 1.25x1.25 mm, 0.187 pF each pixel


Simulations

Simulation model of nXYTER exist. It is very good approximation to real electrical model.

Simulations have been done by Mircea Ciobanu.

Simulations include:

➔ Simulation model of nXYTER

➔ Noise source

➔ Simulation model of detector.


Simulation model od n-XYTER

pics and data: M. Ciobanu


Noise parameters

0.0000000 0.0000005 0.0000010 0.0000015 0.0000020

-0.02

-0.01

0.00

0.01

0.02

0.03

Y A

xis

Titl

e

X Axis Title

noise1.dat

-0.03 -0.02 -0.01 0.00 0.01 0.02 0.03 0.04

0

500

1000

1500

2000

2500

3000

Data: Bin2_Counts1Model: GaussEquation: y=y0 + (A/(w*sqrt(PI/2)))*exp(-2*((x-xc)/w)^2)Weighting: y No weighting

Chi^2/DoF = 1110.57988R^2 = 0.9991

y0 -3.53921 ±12.47874xc -0.00071 ±0.00004w 0.01121 ±0.00011A 40.14697 ±0.45182Y

Axi

s T

itle

X Axis Title

noise1.dat

σn=5.65 mVRMS

6σn

0.00E+000 1.00E+009 2.00E+009 3.00E+009 4.00E+009 5.00E+009 6.00E+00910-20

10-19

10-18

10-17

10-16

10-15

10-14

10-13

10-12

10-11

10-10

10-9

10-8

Frequency (Hz)

Po

wer

-10000-8000-6000-4000-2000

02000

0.00E+000 1.00E+009 2.00E+009 3.00E+009 4.00E+009 5.00E+009 6.00E+009Frequency (Hz)

An

gle

(deg

)

1GHz


Noise model used in simulations.


Step Pulse Response➔ 1 fC Step Pulse response

➔ CDET

= 1, 2, 4, 8, 16, 32, 64 pF

S-voltage vs. timePZ-voltage vs. timeE-voltage vs. time


Noise

0 10 20 30 40 50 60 700

500

1000

1500

2000

No

ise

[e]

CDET

[pF]

E PZ S


Step Pulse Response

1 fC Step Pulse response pics and data: M. Ciobanu

E-out

PZ-out

S-outCDET=1pF CDET=30pF

Sensitiv. tPK tR Slope[mV/fC] [ns] [ns] [V/μs]

Eout 9.95 9.09 1.49 24.5 0.5 10.2 16.3 0.71PZout 9.63 6.61 1.03 11.4 0.44 6.2 17.6 0.88Sout 103.9 89.67 11.6 18.3 6.1 10 13.8 7.4


Electrical noise

1 fC Step Pulse response pics and data: M. Ciobanu

1pF Sensitiv. Noise (500ns) Slope σT

[mV/fC] [mVRMS] [e] [V/μs] [ps]Eout 9.95 0.290 182 16.3 18PZout 9.63 0.289 188 17.6 17Sout 103.9 0.856 52 13.8 62

30pF Sensitiv. Noise (500ns) Slope σT

[mV/fC] [mVRMS] [e] [V/μs] [ps]Eout 9.09 1.472 1012 0.711 2070PZout 6.61 1.396 1320 876 1590Sout 89.7 11.49 800 7.11 1640

Adjust input serial noise as to obtain shaper equivalent outputnoise of 800 ENC corresponding to nXYTER performance.


Electrical noise


CDET=1pF CDET=30pF

1 MIP = 22000 e (0.3mm Si) = ~ 3.5 fC

with noise

without noise

The response to Si equivalentcurrent generator (0.8 MIP)


Discrimination Time

pics and data: M. Ciobanu1 MIP = 22000 e (0.3mm Si) = ~ 3.5 fC

Cdet = 1 pF Cdet = 30 pF

2 4 8 16 32 64 128 2560

1

2

3

4

5

6

7

LE

Dis

crim

inat

ion

time

[ns

]

Qinp [fC]

E PZ S

1 2 4 8 16 32 64 128 2560

5

10

15

20

25

30

LE D

iscr

imin

atio

n tim

e [n

s]Qinp [fC]

E PZ S

Discrimination time for two extreme cases: Cdet = 1 pF and 30 pF


Time Walk

pics and data: M. Ciobanu1 MIP = 22000 e (0.3mm Si) = ~ 3.5 fC

Cdet = 1 pF Cdet = 30 pF

Time resolution for two extreme cases: Cdet = 1pF and 30pF

2 4 8 16 32 64 128 256

0.025

0.05

0.1

0.2

Tim

e r

eso

lutio

n [n

s]

Qinp [fC]

E PZ S

1 2 4 8 16 32 64 128 256

0.0625

0.125

0.25

0.5

1

2

4

8

Tim

e r

eso

lutio

n [

ns]

Qinp [fC]

E PZ S


Future developmentIn next step we can start to do tests

with existing/being developednXYTERs boards, ie.

nXYTER GEMTPC board.

Advantages:

➔ 2 nXYTER chips on board.

➔ Very short connection (~10mm) on middle channels –low input capacitance!

➔ ADC (10 or 12bits) on board.

➔ Existing ROC – we can automate the measurements process.


Conclusions

➔ Simulations works and gives us very interesting informations about data proceedings on the nXYTER chip. Simulation model doesn't match exactly to nXYTER electrical schematic – but is very good approximation.

➔ Simulated noise on fast shaper output is 52 EMC (for 1 MIPS input signal and 1 pF detector capacidance) – excelent S/N ratio!

➔ Signal processing is very fast – of the order of few ns.

➔ It looks like nXYTER is very good readout chip for Diamond Detectors, maybe even better than for Silicon Detectors ;)

➔ Beware! It is very important to keep total input capacitance (pixel+connection cables) lower than 1 pF – for 16 pixels detector (5x5 mm) suggested is 0.8 pF of total input capacidance.


Contact

➔ Rafał LalikAGH-UST Cracow, Faculty of Physics and Applied Computer ScienceGSI Darmstadt - [email protected]

➔ Christian J. SchmidtGSI Darmstadt - [email protected]

➔ Mircea CiobanuGSI Darmstadt - [email protected]





References

➔ Mircea CiobanuIs a Shaper Amplifier needed in the time branch after a CSA?


Questiontime

Thank you for your attention.

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