PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer1 Spectrometer Performance H. Feuchtgruber, T. Müller, A. Poglitsch

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer2 Overview Thermal behaviour Spectral coverage Wavelength calibration Spectral resolution and instrumental profile Sensitivity NEP Relative spectral response Leakage and Ghosts Photoconductor Arrays !! Mostly draft results, no final reports yet !!

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer3 Boundary Conditions Limited Time Apply best guess values for detector biases and heater Measurements have been carried out in few flux regimes with mostly smallest capacitor. Optics misaligment and the significant amount of time spent to investigate it Blue and Red spectrometer had to be operated separately

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer4 Thermal Behaviour (1) Results from CUS Observation: “SPEC_thermal_OBS” Test of all spectroscopy components within one single measurement Illustrate the temperature behaviour of PACS during typical spectrometer and photometer operations Determine FPU temperature upper limits during heat dissipation Measure temperature transients in the individual sub-units Assess overall thermal conductances and heat fluxes Verify proper thermal strapping to cryostat thermal reservoirs Identify possible problem areas

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer5 Thermal Behaviour (2) Results from CUS Observation: “SPEC_thermal_OBS” Test of all spectroscopy components within one single measurement Illustrate the temperature behaviour of PACS during typical spectrometer and photometer operations Determine FPU temperature upper limits during heat dissipation Measure temperature transients in the individual sub-units Assess overall thermal conductances and heat fluxes Verify proper thermal strapping to cryostat thermal reservoirs Identify possible problem areas

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer6 Spectral coverage  Available grating range = degrees working range = 43.1 degrees (low grating output) order “measured”specification [45000 – ] n=3 73.2µm – 34.8 µm 72µm - 56µm n=2109.8µm – 52.2µm* 105µm - 72µm n=1219.6µm – 104.3µm 210µm - 105µm * Nominal 72-56µm band can be measured in grating order 2 and 3

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer7 Wavelength Calibration (1)  Sources and available measurements: - FIR-Methanol-Laser provided by LENS Tested spectral lines: , , , µm - OGSE vapor cell Tested spectral range scans: 58-60µm and µm  =  ;  =  ; g LHe = ; n=[1,2,3] ; pix=[1..16]  =  0 -gratpos/dgratwith dgrat=23301[steps/  ] So far just:  0 (FM) =  0 (CQM)  (no detailed analysis and no module dependence yet !)

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer8 Wavelength Calibration (2) Laser: µm Grating order = 3 Filter A Pixel:11,7 Laser setup in front of cryostat

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer9 Wavelength Calibration (3) Laser: µm Grating order = 3 Filter A Pixel:11,7 Signals beyond cut level in white Measured Gaussfit

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer10 Wavelength Calibration (3) Blue spectrometer, Grating order 3, single pixel Vapor cell p = 20-28mbar Red spectrometer, grating order 1,single pixel Vapor cell p = 8.5 mbar Measured Model Measured Model

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer11 Spectral Resolution & Instrumental Profile 3 laser lines confirm predictions from design on central pixels Instrumental profile is “gaussian” at least down to a residue at 3% level

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer12 Staring measurement at fixed grating position and given OGSE BB input flux has been analyzed (no dark current and straylight considerations yet !): CRE setting: Nominal bias, smallest capacitor, 64 readouts per ramp Sensitivity: System NEP Map blue red  88µm; T BB =30K; P pix =3.96e-14W  194µm; T BB =22.5K; P pix =1.15e-14W

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer13 Relative Spectral Response n=3 n=2 n=1 C int =140fF C int =230fF Draft analysis of different spectral scans on OGSE BB at 30K. Single pixel only Probably saturation effects for red detector at 30K Leakage effects seen at longwave band edges Not yet measured with n=1 57µm105µm72µm leakage

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer14 Leakage and Ghosts (1)

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer15 Leakage and Ghosts (2)

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer16 - Plot of Ghost Responses in 1st Order 0thorder0thorder Leak 2nd order Ghost 2nd order 2pass Ghost 1st order 2pass Normal Signal Ghost 1st order 3pass From SVR 1

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer17 - Plot of Ghosts, 1st Order, with Baffles Leak 2nd order Ghost 2nd order 2pass Ghost 1st order 2pass Normal Signal From SVR 1

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer18 Leakage and Ghosts (3) CQM “ghosts” “clean” FM Successful baffling implemented

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer19 - Leakage effects are within expectations from order sorting filter performances - ECR-011, baffle modifications were successful in removing the sharp spectral ghosts seen during CQM - Tests with the strongest laser line at µm did not show leaking features in the blue bands - No ghosts seen during all laser tests Leakage and Ghosts (4)

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer20 Photoconductor Arrays (1) PACS-ME-NCR-236: “2 pixels low response” PACS-ME-NCR-237: “crosstalk in supply group 2”

PACS SVR 2 18 Jan 2007 FM ILT: Spectrometer21 Photoconductor Array (2) PACS-ME-NCR-237: “crosstalk in supply group 2” (few x 100mV/s up to several V/s) Crosstalk is also present in supply group 1, however much less (few x 10mV/s) Measured “Model” Dummy resistor !