The problem with double

event patterns

(M. Brusa, K. Dennerl – MPE)

EPIC CAL/OPS meeting - MPE

Classification of doubles

read

out

dir

ect

ion

split right(SAS: „2“)

split left(SAS: „4“)

split forward(SAS: „3“)

split backward(SAS: „1“)

SAS 2Right

SAS 3Forward

SAS 4Left

SAS 1Backward

Forward/Backward doubles:superposition of “true” doublesand “false” doubles (re-emissionduring read-out) cause shifts in energy calibration

SAS 2/4: (Left/Right doubles)

resemble singles in illumination

SAS 1/3: (Forward/Backward doubles) different illumination

the amount of forward and backward doubles vary across the detector

11 CALCLOSED observations

(PN + FF + expo > 20 ks) spanning ~1000 revolutions from #84 to #1105

Spectra extracted in 120 different positions

(30x4 quadrants) for - SINGLES (PATTERN=0) - DOUBLES (PATTERN=1-

4)

XSPEC: fit of the MnKα line (5.896

keV) and Al line (1.486 keV) tested against:

- different matrices or models used - singles vs. doubles - backward vs. forward - MnKα vs. Al

Q0 Q1

Q3 Q2

Examples of spectra (MnKα, Rev. #572, Q1)

Singles (black)

D-backward (red)

D-forward (green)

readout

dir

ect

ion

Singles, Q1Single gaussian fit to MnKα

REV #84

Mn line (5.896 keV)

Singles, Q1

REV #125

Mn line (5.896 keV)

Singles, Q1

REV #249

Mn line (5.896 keV)

Singles, Q1

REV #429

Mn line (5.896 keV)

Singles, Q1

REV #981

Mn line (5.896 keV)

Singles: different MATRICES used

Best fit energy line does not depend on the actual matrix used

Singles: different MATRICES used

REV #84

Singles: different MODELS used

Best fit energy line does not depend on the model used

REV #84

Singles vs. Double (1 – backward)

REV #84

Systematic trendPosition of SAS”1”inconsistent with values for the singles

Singles (blue)

D-backwards (red)

readout

dir

ect

ion

Singles vs. Double (1 – backward)

REV #125

Systematic trendPosition of SAS”1”inconsistent with values for the singles

Singles (blue)

D-backwards (red)

readout

dir

ect

ion

Singles vs. Double (1 – backward)

REV #572

Singles (blue)

D-backwards (red)

readout

dir

ect

ion

Singles vs. Double (1 – backward)

REV #857

Singles (blue)

D-backwards (red)

readout

dir

ect

ion

Singles vs. Double (1 – backward)- “detector representation” -

REV #84

“Curved shape”wrt singles

Singles (blue)

D-backward (red)

Singles vs. Double (1 – backward)

REV #125

Systematic in allobservations

Singles vs. Double (1 – backward)

REV #249

Systematic in allobservations

Singles vs. Double (1 – backward)

REV #309

Systematic in allobservations

Singles vs. Double (1 – backward)

REV #429

Systematic in allobservations

Singles vs. Double (1 – backward)

REV #572

Systematic in allobservations

Singles vs. Double (1 – backward)

REV #605

Systematic in allobservations

Singles vs. Double (1 – backward)

REV #709

Systematic in allobservations

Singles vs. Double (1 – backward)

REV #857

Systematic in allobservations

Singles vs. Double (1 – backward)

REV #981

Systematic in allobservations

Singles vs. Double (1 – backward)

REV #1105

Systematic in allobservations

Singles vs. Double (backward) vs. Double (left)

REV #125

Singles (blue)

D-backward (red)

Singles (blue)

D-left (red)

Singles vs. Double (backward) vs. Double (forward)

REV #125 No clear trend seen!

Singles (blue)

D-backward (red)

Singles (blue)

D-forward (red)

Al lineSingles vs. Double (1 - backward)

REV #125

Singles (blue)

D-backward (red)

Mn vs. Al lines (singles vs Double 1- backward)

REV #125

Smaller amplitude ..but similar shape!

MnKα lineAl line

Conclusions/Future developments

Singles: - Mn & Al line energy quite stable (in single observation) - Matrices/models adopted does not affect energy

determination

Doubles: - most of problems caused by BACKWARD (systematic

trend wrt to singles) - LEFT/RIGHT: similar to singles - FORWARD: no systematic trend…

Amplitude in Al line smaller than in Mn line - Energy AND spatial corrections needed