Kaori Hattori 1,2 Chihiro Ida 1,2, Kazuki Ito 2, Kotaro Fujii 3, Hidetoshi Kubo 1,2, Kentaro Miuchi 1,2, Masaki Takata 2,4,5, Toru Tanimori 1,2, Hidehiro

Kaori Hattori1,2

Chihiro Ida1,2, Kazuki Ito2, Kotaro Fujii3, Hidetoshi Kubo1,2, Kentaro Miuchi1,2, Masaki Takata2,4,5, Toru Tanimori1,2, Hidehiro Uekusa3

1Department of Physics, Kyoto University, Japan2 Structural Materials Science Laboratory, RIKEN Harima Institute/SPring-8 Center, Japan3 Department of Chemistry and Materials Sicence, Tokyo Institute of Technology, Japan4 SPring-8/JASRI, Japan5 Department of Advanced Materials Sciences, Graduate School of Frontier Sciences, The University of Tokyo*2008/8/30

IUCr 2008 Osaka, Japan

OUTLINEDevelopment of detectors for structural determinationRequirements for photon counting detectorsNovel photon counting detector, mico-pixel chamber (m-PIC)Time resolved experimentsSmall angle X-ray scattering (SAXS) experimentsSummaryIUCr 2008 Osaka, Japan*2008/8/30


IUCr 2008 Osaka, Japan*To provide powerful methods for structural determination High speed Structural analysis of biological macromolecules (protein materials radiation within a couple of minutes High precision wide dynamic range of >107realize high precision measurementsStructural determination of materials with light elements Time resolved active dynamics photon-induced phase transitionrecord continuum transition with a time resolution of sec to sub-msec repeated measurements will provide better time resolution

To satisfy these conditionsPhoton counting detectors with good position resolutions are suitable2008/8/30


IUCr 2008 Osaka, Japan*1. Position resolution better than 100 m2. Counting rates > 107mm-2, >1000 MWPC (irradiated locally)3. Large active area of > 150150 mm24. No dead region (ex. junctions)5. Efficiency difference < 1 %6. Image distortion < 1 %7. Operation at room temperature, low power consumption8. Easy maintenance9. Low costs

A photon counting area detector based on a Micro Pixel Chamber (m-PIC)has realized 4, 6, 7, 8, and 9.1, 2, and 5 are in progress.3. A n active area of a m-PIC currently in use is 100100 mm2 A m-PIC with an active area of 300 300 mm2 has proved stable runs. Verification experiments at a synchrotron radiation facility are being planned.Readouts without intervalsCRP (continuous rotation photograph) methodHigh gainsensitivity to low energy X-rays of about 1 keVAnomalous X-ray scattering of sulfur (2.3keV2008/8/30


IUCr 2008 Osaka, Japan*100 mm GEMgas electron multiplier)140um70umMechanism for photon detectionPhotoelectric effect in a gasEmitted electron runs until it loses a kinetic energyIonizes atomsElectron clouds are amplified by a GEM(gas electron multiplier, F. Sauli, 1997) , and -PICPixel pitch400 mGas gainm-PIC : 3104 GEM: 3


IUCr 2008 Osaka, Japan*m-PIC is kept in the sealed vesselThe m-PIC is contained in a sealed vessel with a polyimide entrance window of 0.1-mm thickness.The vessel is filled with Xe-C2H6(70:30) gas.Stable operation without freshgas supply for > 1 monthSealed vesselAnode 256ch + cathode 256chSignals from the -PIC are sent via the printed circuit boards100 mm2008/8/30


*IUCr 2008 Osaka, JapanThe output charges of the 256+256 channels are parallel pre-amplified, shaped, and discriminated by the ASD chips completely digitizedDigital signals are sent to the position encoding module with an internalclock of 100 MHz, allowing the recording of position (X or Y) and the timing Tin the memory module2008/8/30


SimpleLow costEasy adjustments for detectors with large active areaFast readout Characteristic less depends on counting ratesGood counting rate capabilitiesm-PIC > 1 MHz charge division < 1 MHz delay line

IUCr 2008 Osaka, Japan*2008/8/30


*the best fit of exponential functionx1.038Error0.7%Irradiated scattering froma piece of glassy carbon 0.9 IUCr 2008 Osaka, Japangood linear correlation from 20 cps to 5 Mcps

Dynamic range of > 105No saturation

counting rates are limited by a high voltage module 2008/8/30


*400m10cm2-dimensional imaging gaseous detectorpitch 400m,size 100 mm100 mm, 300 mm300 mmposition resolution ~ 120mX-ray image of test chart and the projected image along 0.5 mm slitsProjected image of the test chart edge and the best fit of the error functionTakeda et al., IEEE Transactions on nuclear science, Vol. 51, No.5, (2004) Theoretical limitKnife edge test2008/8/30IUCr 2008 Osaka, Japan


2008/8/30IUCr 2008 Osaka, Japan*CRP (continuous rotation photograph) methodMovie of diffraction spots from rotating crystals a crystal rotated by a goniometer timings of incident photons converted to rotation angles of diffraction spots

Reducing the measurement timeStrong background reduction using a new parameter, rotation angle


integrated diffraction spots

IUCr 2008 Osaka, Japan*Movie varying 2q continuously Time resolution of ~ 100 ns for each X-ray Much Information -> quick online analysisTimeMSGC(Micro Strip Gas Chamber)Reciprocal lattice2008/8/30

Crystal Ref. #R-factor (I > 2s ) time (sec.) C4H9NO61,4067.9%2.1C20H37CoN6O44,3619.8% 300C25H26O44,5658.4% 80


Applying the noise reduction using 2q information rotation speed : 4.89 sec/cycle mesurement time : 3716 sec counting rate : 1.05104 cpsTakeda et al.J. Synchrotron Rad. (2005)12, 820-8253716s 2q

IUCr 2008 Osaka, Japan*BL14A17.5keVPICcrystal 2008/8/30


IUCr 2008 Osaka, JapanhydratedehydrateKEK Photon Factory 0.7Dehydration reaction of a pyromellitic acid hydrate occurs while heat is applying (140)65 secChange in a diffraction pattern in 7 sec2008/8/30*


*0 sec1.95 sec3.90 sec6.50 secThe intensity I(2, t) is expressed as I = xId (2)+ (1-x)Ih (2),where Id (2), Ih (2) is the intensity of the dehydrate, the hydrate, respectively, including a background4.3104 events / 0.65 secTime resolution will be expected to about 4 msec with a count rate of 10MHz


IUCr 2008 Osaka, Japan*Camera length 0.63.5mbeamtarget2008/8/30


*Diffraction patterns of collagen with a -PIC X-ray imaging system with an accumulation of 106 events, 105 events, and 104 events, respectively.Signal-to-noise ratio in the background of the diffraction pattern was improved0.9 , 1.2 105 cps2008/8/301122


solution scattering from polystyrene latex(110 nm, 5 mg / ml), 1.5 IUCr 2008 Osaka, JapanNo spatial distortion was observed100 mm2008/8/30*irradiating a grid mask with scattering from a piece of glassy carbon, 1.5 The peaks observed at the holes on the mask moved < 10 mm when the beam intensity was varied from 8 to 200 kcpsHoles were perpendicularly arrangedThe deviation from the perpendicular was

IUCr 2008 Osaka, Japan*q-4Polystyrene latex0.04 weight %solid spheres of 110-nmdiameter1.5 exposure time : 154 sec

Incident photon flux1.5 1011 photons / s

dynamic range Six orders of magnitudeCCD: 104Imaging Plate: 105-6106Close to edge of the detectorLow detection efficiency2008/8/30


*IUCr 2008 Osaka, JapanApo-Ferritin1.5 exposure time : 436 sec

Solution (m -PIC)Water (m -PIC)Solution water (m-PIC)R-AXIS (IP)

Incident photon flux1.5 1011 photons / s

Deviation from IP was seen in high-q region.Signal to noise ratio stronglyeffects on low-countingrates region.Further studies are necessary.2008/8/30


2008/8/30*Achieved by Gamma-ray camera based on a -PIC

currentgoalpitch400 m200 mNumber of electrodes256 2561500 1500Active area100 100 mm2300300 mm2Gas gain5103 104 > 104Dynamic Range> 106107Intensity Range(Global)< 5MHz10MHzEfficiency uniformityseveral %< 1%distortionNoNo


good linear correlation > 105 (20 cps 5 Mcps)Position resolution of 120 umCRP method : Rint (internal agreement factor)3.7% Time resolved measurementsImage without distortionDynamic Range of > 106

2008/8/30IUCr 2008 Osaka, Japan*


IUCr 2008 Osaka, Japan*A photon anode : a few signals for 100 ns cathode : a few signals for 100 ns

coincidence

To avoid accidental coincidence Further improvements are necessaryanode20 ns20 nscathodeChoose between two possibilities:One is correctThe other causes accidental coincidence

Cut events when another event comeswithin approximately 20 ns 2008/8/30


Small-angle neutron scattering at JRR-3, Japan in SeptemberSolution scattering experimentsat Spring-8, Japan in October

Increase detection efficiencydyamic rangeConfirm consistency underhigh and low-count rate environmentsLarge m-PIC with an active areaof 300300 mm2 in developmentIUCr 2008 Osaka, Japan*2008/8/30


*First, Im going to refer structural determination and what are necessary for improving it.Next, Im going to talk about requirements for photon counting detectors.****The micro-pixel chamber, we call it u-PIC, is being developed at Kyoto University.This is a schematic of our detector. The detector is contained in a sealed vessel, as shown in this photo,and filled with a xenon gas. The detection area is here. When a photoelectric effect occurs here,emitted electron runs unitil it loses a kinetic energy. During this process, atoms in the gas are ionized.Electron clouds move toward a gas electron multiplier placed above the u-PIC.And then they amplified by the GEM and the u-PIC.

*The detectors data-acquisition system consists of amplifier-shaper-discriminator (ASD) chips (Orito et al., 2004), a position encoding module (Kubo et al., 2005), and a memory module on the VME bus. A block diagram of the data acquisition system is shown in Fig. 3. The output charges of the 256+256 channels are parallel pre-amplified, shaped, and discriminated by the ASD chips whose integration time constant is 80 ns. The time constant of signals integrated by the ASD chips was determined by the integration time of charges generated in the m-PIC. A reference threshold voltage was commonly supplied to all the ASD chips. All discriminated digital signals are sent to the position encoding module consisting of Field Programmable Gate Arrays (FPGA) with an internal clock of 100MHz, allowing the recording of the anode and cathode coincident position= (X, Y) and the timing (t) in the memory module. Thus, the position encoding is completely executed by digital processing. ***Obtained by knife edge test*Time resolved X-ray crystal structure analysis has been succeeded using other gas detector, a micro strip gas chamber.**The CRP method provides a new parameter, a rotation angle, so we can display diffraction spots in a three-dimensional space. As shown in these figures, it gets easier to apply good noise reduction. The diffraction spots cluster. So, events outside clusters should be noises. The change in the diffraction pattern is clearly recognized.*You can see the diffraction pattern changes as heat is applying.The weight fraction of hydrate decreased from 1 to 0 within 7 sec.We records the weight fraction every 0.65 sec using 4.3 times 10 to the forth events.The X-ray intensity was low, so the time resolution was not good, but when a counting rate is 10 mega hertz,the time resolution would be deduced 4 mili seconds from this experiment.*

Documents

Kaori Hattori 1,2 Chihiro Ida 1,2, Kazuki Ito 2, Kotaro Fujii 3, Hidetoshi Kubo 1,2, Kentaro Miuchi 1,2, Masaki Takata 2,4,5, Toru Tanimori 1,2, Hidehiro