Measurements at LNLS with Thin Timepix assemblies

Mathieu Benoit

Outline

• Experimental facilities

• Measurements

• Data Analysis and impact on Calibration

LNLS Experimental facilities

15 beam lines in operation : • X-Ray diffraction (XRD)• Crystallography (MX)• Small Angle X-Ray Scattering (SAXS)• X-Ray Absorption and Fluorescence

(XAFS)

For our measurements we use 3 beam lines : • SAXS1 (Pinhole experiment)

• Energy Resolution 10% (8 +-0.8 keV)• 1E12 photons/s• Divergence 900 x32 urad @ 8keV

• XAFS1 (Energy scan for single pixel calibration)• Energy range 4-15 keV Resolution : 0.0001%• Beam Size 1x1 mm2• 1e9 photons /s @ 7 keV

• MX1 (Pinhole and Fluorescence calibration)• Energy = 7.7keV + harmonics • 1e12 photons /s • Various targets for calibration

Fluorescence measurements (MX1)

Target Co Cr Cu Fe Mn Ni Ti V Zn

E (kα) in keV

4.51 4.95 5.414 5.89 6.4 6.93 7.47 8.04 8.63

X-Ray beam (7.9,15.8 keV)1e12 photons/ s

Target

Fluorescent photons field

~ 1000 single pixel clusters per pixel / 50k frames (1ms integration) -> ~30-45 min per fluoOnly tested with one assembly (A06-W0110) but possibility to run multiple assemblies at the same time (Large Fluorescence radiation field )

Timepix+FITPix

Single Pixel TOT Spectrum

First Harmonic scattered

Calibration Curve

Single Pixel Energy Spectrum

First Harmonic scattered

Application to testbeam data

Old Calibration New Calibration

By Sophie Redford

Application to testbeam data

Old Calibration New Calibration

By Sophie Redford

Impact on resolution

• Resolution in X, 2 hit cluster: 5.124 um -> 4.893 um

• Resolution in Y, 2 hit cluster: 4.986 um -> 5.265 um

• Resolution in X 4 hit cluster: 6.269 um -> 6.166 um

• Resolution in Y 4 hit cluster: 6.211 um -> 6.481 um

Energy Measurements with monochromator (XAFS1)

X-Ray incident beam goes to Crystal Monochromator and is then delivered to the experimental area. Energy can be selected with 0.1keV accuracy along the 5-15 keV range. 2 sensors (C04-W0110,D09-W0126) were tested in this beamline to obtain single pixel calibration for a subset of pixel (beam 2.5x3mm2)

Analysis on one of the sample will be presented by Mateus Vincente for UFRJ

Single Pixel TOT Spectrum

I cant see the 5-8 keV photon peak,Double count peaks are however visible

Global Surrogate Fit

Global calibration seems to work nicely with C04-W0110 , however it is not the case for the two assemblies tested with the monochromator.

Next steps : • Feedback to LNLS to understand better

the X-Ray content of the beam

• Pixel per pixel analysis to see if results can be improved

• Use better fit method with convolution of the surrogate and gaussian as the data point are in the lower energy region

Issues with current measurements and further steps

Conclusion• First measurements at LNLS were conducted successfully,

and 3 set of measurements were performed– Fluorescence– Pinhole experiment – X-Ray spectroscopy with monochromator

• First results already brought improvement to our calibration and gave more insight on the behavior of the device. More work is needed to refine the results and extract single pixel information

Thanks to the test beam team from LNLS and UFRJ !!