EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Origin of gain offsets: new insights from eROSITA calibration Mallorca, Spain, 2008 April EPIC Calibration & Operations Meeting

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Gain/temperature correlation: earlier investigations

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Mn-K α position vs. temperature: CCD 3 & 4

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Deviations of the Al-K and Mn-K α positions

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Mn-K α position vs. Al-K position

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 “CCD offsets”

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 ART-XC (Ru) eROSITA (D) Calorimeter (NL,US,J) LWFT (UK) "LOBSTER" Spacecraft "Navigator" (Ru) Spektr-Rentgen-Gamma (SRG) to be launched in 2011 from Baikonur into 600 km / 30° orbit with Soyuz-Fregat Спектр-рентген-гамма

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 eROSITA

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 eROSITA / TRoPIC calibration Energy [keV] x = x = Energy [keV] adu

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 eROSITA / TRoPIC calibration Energy [keV] peak position: deviation from nominal value [adu] x = x = Energy [keV]

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Deviations of the Al-K and Mn-K α positions

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 eROSITA / TRoPIC calibration “charge loss” independent of energy simulation Energy [keV] peak position: deviation from nominal value [adu] Energy [keV] - 25 adu- 35 adu

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 eROSITA / TRoPIC calibration “charge loss” dependent on energy simulation Energy [keV] peak position: deviation from nominal value [adu] Energy [keV] - 25 adu · exp(-E/keV)- 35 adu · exp(-E/keV)

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 “Gain offsets” are observed at EPIC pn and eROSITA Due to the enhanced spectral capabilities towards lower energies, they can be better studied with eROSITA..

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 eROSITA / TRoPIC input: 6 long flatfield exposures at B-K, C-K, Cu-L, Al-K, Cr-K, Cu-K selection of all singles in the 20 CCD rows closest to the CAMEX no corrections applied peak positions determined separately for CAMEX-1 and CAMEX- 2

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 offset: ~ eV 0 ~ 14 eV

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 eROSITA / TRoPIC Application of the cti and gain correction derived for singles

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 HK Al-K monochromator (1.486 keV), NLL=0A00 (10s), SPLT=0028 (40a)

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Cu-K (8.040 keV) high threshold (~130 adu)  overcorrection of doubles not due to noise collection

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Cr-K (5.410 keV)

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 B-K Cr-K Cu-K Al-K

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8  Patterns cannot be corrected by any gain(E) function which is applied to their components individually, even if this function is made dependend on (x,y) and the pattern type.  If correction for singles is applied, then patterns become overcorrected, with the amount of overcorrection monotonically increasing with pattern size What is the reason ? why offset ? why overcorrection for patterns ? eROSITA/TRoPIC Gain Correction

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 nonlinear amplification ? offset calculation ? common mode ? pileup with noise ? frame store ? partial events ? why offset ? why overcorrection for patterns ? eROSITA/TRoPIC Gain Correction

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 E = 0.1 keV E < 0.1 keV E = 6.0 keV 5.9 keV E = 5.9 keV 0.1 keV E = 0.1 keV Charge Loss due to Partial Events

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 nonlinear amplification ? offset calculation ? common mode ? pileup with noise ? frame store ? partial events ? why offset ? why overcorrection for patterns ? threshold ! eROSITA/TRoPIC Gain Correction

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 General consequences Low Energy Threshold 6.1 million events data corrected with gain derived from singles data set: HK Macor, 15 kV, 4.2 V, EPIC-Filter, 5 Sigma, 20 adu

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Dependence of the peak position derived from singles on the low energy threshold Low Energy Threshold 6.1 million events data corrected with gain derived from singles data set: HK Macor, 15 kV, 4.2 V, EPIC-Filter, 5 Sigma, 20 adu

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 20 adu 30 adu 40 adu 50 adu 60 adu 70 adu 80 adu 90 adu 100 adu 110 adu 120 adu 130 adu 140 adu 150 adu 160 adu 170 adu 180 adu 190 adu

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 HK

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Threshold Induced Charge Loss zero level threshold

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Threshold Induced Charge Loss zero level threshold

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 offset: ~ eV 0 ~ 14 eV eROSITA/TRoPIC Gain Correction

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 eROSITA / TRoPIC calibration Energy [keV] peak position: deviation from nominal value [adu] x = x = Energy [keV]

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 deviations of the Al-K and Mn-K α positions XMM-Newton / EPIC pn

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Single: 4 borders Double: 6 borders 2 singles: 8 borders  border filling factor: 6/8 Triple: 8 borders 3 singles: 12 borders  border filling factor: 8/12 Quadruple: 8 borders 4 singles: 16 borders  border filling factor: 8/16 Patterns, Borders, and Threshold Induced Charge Loss

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Single: 4 borders correction for 4 borders  predicted overcorrections: d : t : q = 3 : 4 : 6 Double: 6 borders but: correction for 8 borders  overcorrection: -6/8 + 8/8 = +2/8 = Triple: 8 borders but: correction for 12 borders  overcorrection: -8/ /12 = +4/12 = Quadruple: 8 borders but: correction for 16 borders  overcorrection: -8/ /16 = +8/16 = Patterns, Borders, and Threshold Induced Charge Loss

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Cu-K: doubles: +67 eV triples: +95 eV quadruples: +157 eV measured: d : t : q = 2.6 : 3.6 : 6.0 predicted: d : t : q = 3 : 4 : 6 ratios somewhat different for lower energies: partial event effect ?

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 eROSITA / TRoPIC calibration “cutoff” gain “cutoff” gain + “electronic” gain nonlinear “electronic” gain

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Implications for the gain correction algorithm for pn CCDs: 1.apply first the “electronic” gain correction to all events (i.e., singles and pattern components) 2.recombine the events to photons 3.apply then the “cutoff” gain correction (depending on energy and pattern size) to all photons in order to recover the lost charge and to linearize/adjust the energy scale  first results: eROSITA/TRoPIC Gain Correction

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Macor B-K (0.183 keV) keV keV keV keV singles doubles triples quadruples

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Al-K (1.486 keV)Cu-K (8.040 keV) keV keV keV keV keV keV keV keV singles doubles triples quadruples singles doubles triples quadruples

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 The situation for EPIC pn While there is clear evidence for an offset in the gain, there is no overcorrection of the energy for patterns observed

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 EPIC pn

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 EPIC pn

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8... EPIC pn

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Implications for the gain correction algorithm for pn CCDs: 1.apply first the “electronic” gain correction to all events (i.e., singles and pattern components) 2.recombine the events to photons 3.apply then the “cutoff” gain correction (depending on energy and pattern size) to all photons in order to recover the lost charge and to linearize/adjust the energy scale For EPIC pn, this is important because it can be considered as a justification for introducing an additive term in the gain correction. It is less important for patterns, because no overcorrection of the pattern energy is observed.

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8 Comparison: eROSITA  EPIC pn Specific properties of eROSITA compared to EPIC pn: CTI correction less important non-linearities of the gain more important lower energies accessible smaller pixels  edge effects more important smaller pixels  increased number of patterns improved charge transport  artificial pattern creation during readout (‘vertical doubles’) suppressed threshold induced gain changes easier detectable Specific properties of eROSITA compared to EPIC pn: CTI correction less important non-linearities of the gain more important lower energies accessible smaller pixels  edge effects more important smaller pixels  increased number of patterns improved charge transport  artificial pattern creation during readout (‘vertical doubles’) suppressed threshold induced gain changes easier detectable

EPIC Calibration Meeting, Mallorca Origin of gain offsets K. Dennerl, 2008 April 8