Number of signals usedType of signalsTests with regular and irregular gridsLast resultsNew idea for minimization function

Roberto VenturelliRoberto Venturelli University of Padova and INFN,University of Padova and INFN,

ITIS “G.Marconi”-VeronaITIS “G.Marconi”-Verona

PSA team, Orsay, June 28, 2007

GRID SEARCH – last newsGRID SEARCH – last news

5

5.2

5.4

5.6

5.8

6

6.2

6.4

6.6

6.8

7

0 5 10 15 20 25 30 35

#Transients

FW

HM

at

1762

keV

(ke

V)

I suggest to have available all the segment signals, then every PSA code will get those significant transients with a proper mask

Number of signals usedNumber of signals used

Number of neighbour transients at the net charge signal assuming a simple geometrical point of view (about 10)

Number of neighbours obtained from a statistics of transients when the hit occurs in the segment base (about 18)

Analysis done using:• preamplifier signals • MWD signals (a first electronic response correction at LLP)

+ raw calculated signals

Type of signals used:Type of signals used:preampl. signals, MWD signals, currents, DWT coeff.,… ?preampl. signals, MWD signals, currents, DWT coeff.,… ?

preamplifier signalspreamplifier signals

MWD signalsMWD signals

current signalscurrent signals

MWD: how many poles needs to be corrected?MWD: how many poles needs to be corrected?

500ns 47s2nd pole 1st pole

preamplifier signals

MWD signals

The analysis with MWD signals improves the PSA performance

This format is already available at the local level processing, the calculated signals require an equivalent AA filter

All the signals need to be calibrated at every fold, with a time zero reference, possibly, time shifts between channels can be managed

I’m NOT confident with this minimization !!!

34416 26391 4164 32056

Tests with grids: regular and irregular Tests with grids: regular and irregular

At the moment the best result with my method is obtained with regular grid of 2mmWe have to continue the investigation to an irregular grid close to 1mm because there is something to gain ! (…limiting the processing time)

Tests with grids: regular and irregular Tests with grids: regular and irregular

Irregular Regular

1380

1380.5

1381

1381.5

1382

1382.5

1383

0 5 10 15 20 25 30

RUN#

Ene

rgy

peak

(keV

)

ge2

ge1

ge0C

AL

IBR

AT

ION

S

Improvements in Doppler Correction Improvements in Doppler Correction

Analysis restricted to a subset of events for change of position during calibrations

Improvements in Doppler Correction Improvements in Doppler Correction Internal calibration with segments

Core energyF=1 (4.4)F=2 (4.3)F=3 (4.3)

Segment energy 1st calibr.Energy shift

Segment energy 2nd calibr. F=1 (4.2)

Segment energy calibr. atF=2 (4.8)Not good!

At low energies and with high counting rate segments energy is preferable at core energy

The sum energy correction at fold 2 and more needs to be verified

These tests are PSA independent

The full calibration of the segments is a relevant step that has to be done before PSA

Other misunderstood problems are still present in the frontal part

Improvements in Doppler Correction Improvements in Doppler Correction

1.5

2

2.5

3

3.5

4

4.5

5

5.5

6

6.5

0 500 1000 1500 2000

FW

HM

(k

eV

)

energy (keV)

First experimental results AW

Subset analyzedInternal segments calibrationPSA with MWD signals

Last results

1381

Improvements in Doppler Correction Improvements in Doppler Correction

Subset analyzedSegments calibrationPSA with MWD signals

Doppler Correction versus ZDoppler Correction versus Z

3.6

3.8

4

4.2

4.4

4.6

0 1 2 3 4 5 6 7 8 9 10

FW

HM

(ke

V)

Z axis

These tests could help to study the quality of the calculated signals at different z and also the capability of the PSA method to identify positions

New chiNew chi22 minimization function minimization function

tminA

tmaxA tmaxA

tminA

Three different transient shapes

New chiNew chi22 minimization function: minimization function: ii

tt

aa

Measured signalsSignals associated at the 1st point in the base

Signals associated at the point in the base thatminimizes the function

After the first tests this method gives Dc of 4.5 keV @ 1382 keV