1

xCAL monitoring

Yu. Guz, IHEP, Protvino

I.Machikhiliyan, ITEP, Moscow

2

Histogram analyzing algorithmsThe prototypes of the following algorithms foreseen are being prepared:

✜ gain monitoring (or calibration) procedure: follows gain variations, updates CondDB when necessary. Works on “summary” histograms, relatively few events per saveset (≤100) sufficient

✜ histogram analyzer: analyzes positions and shapes of signal and pedestal peaks, issues warnings. Works on histograms for individual channels with several K events

The calibration farm and some software components are not available yet (coming soon) still algorithm development on stored LED data. Should be transformed then into “farm-ready” versions.

HistogramAnalyzer

HistogramAnalyzer

Histogram Database

ROOThistograms

Histogram producer(ORWELL task)

Calibration Farm

Histogram adder

Saver

Histogram presenter

Alarms to ECS

CondDB updates

ECAL LED DATA available

only timing scan data available (according to Twiki) “default” (bad) time alignment, too few signal events (20÷30) (see the next page) ok for pedestal studies

ECAL LED DATA (cont)

Prev2 Prev1 T0

Next1

Next2

5

HCAL LED data available

Several short runs with LEDs taken, in order to study the gain monitoring (“calibration”), with “almost” nominal HV (Et_max=15GeV) and LED intensity corresponding to ~3000 ph.el. in each PM. The amplitude varies from ~200 ADC counts in the centre to ~3000 at the periphery. Only LEDs #1 of each module were used. Half of LEDs were fired in each event: the TSB patterns 101010… and 010101…TAE events with 5 BX.

Runs with slightly deviating settings in some cells (namely, module 14) were taken, in order to study the gain monitoring procedure.

Histogram analyzer - I

Tasks: determine pedestal and LED signal position and width; classify channels according to their spectra; produce summary DQ histograms;

Preliminary algorithm has been developed (using root files produced by Orwell v1r3) and now under polishing

Histogram analyzer - II

HCAL: pedestal positionNB note the difference between Inner and Outer parts

HCAL: LED signal amplitudebad channel

Histogram analyzer - III

ECAL: pedestal position ECAL: pedestal widthNB crate 8 FEB 3

ONLINE Histogram binning

ONLINE processing: minimize amount of data to transfer; Instead of one 4096-bin histogram per channel, Orwell produces three, ~100…200 bins each:

xCal/Signal (detailed spectrum, 1 ADC count/bin) xCal/SignalBis (full ADC range / ~100 bins) xCal/Pedestal (detailed spectrum, 1 ADC count/bin)

ONLINE processing: histogram parameters have to be taken from DB for each individual channel; ✔ A set of histogram parameters for ECAL/Pedestal, HCAL/Signal and HCAL/Pedestal was produced;

ONLINE Histogram binning

HCAL: pedestal range HCAL: Signal range

ECAL: pedestal range

Histogram analyzer - IV Current classification (both for PM and PIN):

1. Channel OK2. Empty Channel (no ADC readings or no histogram available)3. Bad number of peaks in the distribution (bit errors, timing lost, etc)4. Bad pedestal distribution shape (by Chi^2 of the fit)5. Bad pedestal position / width6. Absent LED signal7. Bad LED distribution shape (by Chi^2 of the fit)8. Bad LED position / width (i.e. ADC overflow)

Control sum

2

3,4,5

6

7,8

%

Histogram analyzer - V

χ2/n.d.f. of the Gaussian fit of pedestal and signal peaks turned out to be a good parameter to monitor

HCAL Pedestal (all C-side cells) HCAL LED (all C-side cells)

Histogram analyzer - VI

Signal in ECAL: no reliable χ2/n.d.f. distribution, very limited statistics

ECAL, χ2/n.d.f for pedestal

Worse fit than in HCAL, because of the noise tails

Histogram analyzer - VII

HCAL Pedestal fit Chi^2 / ndf

Pedestal spectrum in the bad channel (see prev. slides) is not Gaussian (ATI connector problem, now fixed)

Histogram analyzer - VIII

ECAL Pedestal fit Chi^2/ndf

R/O crate 8, FEB 3 – all pedestal distributions have non-Gaussian shape

Histogram analyzer - IX

ECAL: it may be useful to monitor the noise sweep

one ‘noisy’ power line is clearly seen (plot from ‘C-W noise’ note)

17

Outer cell mod #14 Inner cell mod #14

The procedure was tested on the sequence of all runs (06,07,08,09) (for the moment, as an algorithm in Orwell). The amplitude was averaged over 50 events; PINs: “T0”+”Next1”; PMs: “Prev1”+”T0” (emergency measure, because of not perfect time alignment). “Update” threshold was 4% (for the moment, just types to the screen).

PIN mod #14

run06

run07

run08

run09

Outer cell mod #12

run06

run07

run08

run09

LED calibration procedure: test on HCAL

18

In the meanwhile, a very unstable PM was found (very high rate effect, to be fixed), and few less unstable ones, to be investigated

LED calibration procedure: test on HCAL

19

Check of the PIN correction for the LED intensity variation: 26% 2.7% -- not perfect, but maybe satisfactory for HCAL (for ECAL – to be studied)

26%

2.7%

run06

run09

run06

run09

LED calibration procedure: test on HCAL

20

Pedestals: nonzero in crate 22 (Outer section + PINs) crosstalk ~1% ;negligible in crate 23 (Inner section) : to be investigated (study the crosstalk pattern)

Outer cells crate 22

PINscrate 22

Inner cells crate 23

LED calibration procedure: test on HCAL

21

● Take more data for ECAL and HCAL:

● long runs (several hours), to study the stability, and measure the stabilization time after HV ON in various conditions

● vary PM HV and LED flash intensity, in order to take regulation curves

● vary LED firing sequence, to study the crosstalk pattern; choose optimal sequence

● etc…

● Prepare “farm-ready” versions of the procedures.

Plans for the nearest future