lav front-end threshold study

LAV front-end threshold studyMauro RaggiFrancesco Gonnella

5th February 2013

Photon Veto Working Group Meeting

Mauro Raggi - I.N.F.N. - Laboratori Nazionali di Frascati - Italy

Outline Noise studies

Inside Wiener crate Outside wiener crate

Threshold offset studies Using different gain G=5. Threshold offset fine tuning technique Noise at G=5

MIP efficiency studies


Noise tests @ LNF We get two different runs for each test

No signal: all final conditions but pulser is Off Signal: 100mV signal and pulser On

We performed a lot of test: In Crate thr 0 mV nominal In Crate thr 2 mV nominal In Crate thr 5 mV nominal In Crate thr 7 mV nominal

Board moved outside the crate powering it with linear PS We immediately concluded that the situation is improving We did test in the Owen with power from outside


Noise in WIENER crate 2mV thr

No signal 100mV signal

Rate in Hz extrapolated using the total effective acquired time:Tacq = 3.5E3 * 0.5E-6 * 7 = 1.2E-2sThe noise rate goes to ~Hz if the nominal Thr is higher than 7mV (nominal)


Noise linear PS 2mV thr

The board has been moved out from the crate to a table and the ±7.5V power is provided by an external linear power supply.

No signal 100mV signal


Block time resolution examplesOutside crate G=5Inside crate G=3

The uniformity of the time resolution is excellent in the outside crate situation while shows problems due to noise inside the crate.

The noise itself! On top: noise shape

taken from sums outputs

Bottom: output of FEE digital signal after LVDS to NIM converter

Noise frequency 594KHz which seems to match the operating frequency of different low voltage switching regulators

The noise is coming from the wiener power supply.

Suspect improper grounding in the LNF lab. Test at CERN is foreseen


Thr offset and amplification We changed the the board 26 amplification setting up 16

new mezzanines modified to get gain=5. The thr offset have been measured using both G=3 and G=5

with the same procedure in the Front End Test stand

The values of mean offsets scale in reasonable way: Model needed to compensate for amplification

Threshold linearity scan performed

G=5G=3


Equalization quality tests Using just the measured values of the offset with LavFeeTest

We equalized at 10 mV DAQ(Thr (95%))= required value – Offset Measured the new thr offset with the usual method

The quality of the equalization is very good s = 0.15 mVThe absolute value has to be corrected for amplification (G=5) 1.43 factor which leads to ~13. mV at the comparator level


Noise conditions G=5 2mV out

Some extra hits observed in presence of the signal with G=5;No extra activity with pulser Off


Threshold linearity test G=3

All the thr are linear over the explored range

Lines have almost the same slope: (1.16 ± 0.02)(mV pulser)/(mV DAQ)

0 5 10 15 20 250.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

f(x) = 1.16702275769746 x + 6.75353949129853R² = 0.99995180493508f(x) = 1.16178982597055 x + 6.36419410977242R² = 0.999952774678281f(x) = 1.16926773761714 x + 5.6715234270415R² = 0.999936709022736

f(x) = 1.15593172690763 x + 8.77838152610442R² = 0.999952409514456

Pulse

hei

ght [

mV]

@ 9

5%

Programmed DAQ value [mV]


Threshold linearity test G=5

Lines have almost the same slope: (0.70 ± 0.01)(mV pulser)/(mV DAQ)

0 5 10 15 20 250.00

5.00

10.00

15.00

20.00

25.00

f(x) = 0.708447121820616 x + 3.8703641231593R² = 0.999857869758641f(x) = 0.708447121820616 x + 3.8703641231593R² = 0.999857869758641

f(x) = 0.690963855421687 x + 5.1760843373494R² = 0.999782545592171f(x) = 0.683215528781794 x + 3.40375635876841R² = 0.999498139272081

Pulse

hei

ght [

mV]

@ 9

5%

Programmed DAQ value [mV]


The MIP efficiency measurement

We mounted the LAV FEE026 on the oven and get an acquisition with the following scheme:

We set the thresholds to equalized values using DB Offset values

Using the channel with the single column signal (12-15) we got the efficiency of the 12 equalized blocks at different thresholds More stringent trigger is also used for the analysis

0

1

2

3

4

5

6

7

8

9

10

11

12 13 14 15Trigger

Trigger 12 13 14 15


Triggers performance

Only trigger column coincidence signal Added the request for at least 1 other block in the column


MIP efficiency oven triggers

The average MIP efficiency is quite different:

Is that due to different muon sample or to noisy oven triggers?

1 more blockOven Trg

Spurious effect due to trigger request and inefficiency in last channel


Block time resolution

Resolution order 2ns with no slewing correction and unknown trigger time resolution included!

Strange peaks in the distribution.

s ~ 0.5ns/√E


Leading and leading-trailing EffLeading and trailingLeading only

The leading and trailing difference seems not so big as we could expect! Investigating…

5mV 10mV


Threshold scan results: 1 more block in the trigger

Thr = 5mV

Thr = 10mV

Thr = 7.5mV

Both boards thr and oven equalization look reasonably good for low thrsSecond order fine tuning can be obtained using HV or thr adjustments


The ToT puzzle


Conclusions Status:

We discovered the origin of noise (Wiener PS) The quality of equalization procedure seems good We obtained a first estimate of muon efficiency to

be ~90% at 5mV thr with G=5 in the board. First look at time resolution seems Ok.

Things to do: Check the effect of oven extra cables on signal shape and

efficiency Finish trigger optimization (time cuts) Try to further increase the amplification G=6 G=9? Fix an amplification value on the basis of g data spectrum (data

and MC)

Thank you for your attention

lav front-end threshold study

Documents

crate g

mv thr

mv nominalin crate thr

laboratori nazionali

mv nominalmauro raggi

mv outmauro raggi

amplification g

mv nominalboard