1 Performance of a CCD tracker at room temperature T. Tsukamoto (Saga Univ.) T. Kuniya, H. Watanabe (Saga Univ.); A. Miyamoto, Y. Sugimoto (KEK); S. Takahashi, N.Tamura (Niigata Univ.); K. Abe, T. Nagamine, Y. Shirasaki (Tohoku Univ.); T. Aso (Toyama National College of Maritime Technology)

2 Outline Introduction HPK CCD Experimental setup Response to charged particles –S/N, detection efficiency, energy resolution –Position resolution Comparison with EEV CCD Summary

3 Advantage of CCD for tracking device Pixel detector –unambiguous reconstruction/high granularity Thin  extremely low capacitance –less multiple scattering Serial readout –small number of channels Continuously sensitive –no intrinsic limitation as regards trig. rate Other R&D –driven by commercial interest (video) as well as X-ray astronomer, etc.

4 Vertex detector application in future LC Low repetition rate ~150Hz  serial r/o Highly collimated jets  pixel detector Backgrounds  pixel detector to reduce material to keep mechanically stable to avoid interference with the beam monitor Operation at room temp. (~0ºC)  compact cooling system

5 Hamamatsu (HPK) CCD Feature –Full frame transfer type –2phase CCD –MPP operation to reduce dark current Developed for scientific researches –Low light level measurements (e.g. spectroscopy) –X-ray astronomy Application for high energy physics  How about MIP detection? especially at higher temperature

6 Structure of CCD HPK S5466: Full Frame Transfer Type (2phase)

7 MPP(Multi Pinned Phase) Operation Holes are accumulated under Si/SiO 2 interface. Thermal excitation of electrons is significantly suppressed. “Inverted Operation” in other words  Reduction of the dark current by one order of magnitude

8 Specification CCD: Hamamatsu S5466 Driver: Hamamatsu C

9 Experimental setup 4 layers –to reduce random hits –minimize multiple scatterings a special package w/ a hole CCD2 & CCD3 as close as possible KEK PS T1 line –4 sec/cycle –2.0GeV, 1.0GeV, 0.5GeV (–)(–)

10 ＢＥＡ Ｍ 2nd layer Setup Standard CCD Special CCD w/ a hole 1.2mm Al 2 O 3 behind the chip

11 Response to Charged Particles 2x2 clustering S/N

12 S/N as a function of temperature 4sec readout cycle 1.3sec readout cycle

13 Detection Inefficiency for MIP Detection inefficiency assume Gaussian shape in the low energy side of Landau

14 Energy Resolution for MIP Energy resolution

15 Position Resolution After the careful alignment... Position resolution Two components seen  can fit to double Gaussian

16 Charge sharing  Position resolution Charge sharing As “ratio” Position resolution component increases gets close to 1, gets worse.

17 Momemtum dependence of position resolution Position resolution as a function of p Fits well to the formula (multiple scattering) Resolution  0.20  0.01 pixel

18 Intrinsic Resolution Assuming all the sensors have the same resolution,  intrinsic = 3.0  0.2  m (weighted  w/ double Gaussian)  intrinsic = 3.6  0.2  m (RMS) x１x１x１x１ x2 x3 d1 d2

19 EEV CCD CCD –#pixels: 385(H)  578(V) –pixel size: 22  m  22  m –active depth: 20  m Two operation modes –normal mode –“inverted mode” =“MPP mode” in HPK

20 EEV normal mode v.s. inverted mode Dark current Suppression factor ~25 Normal mode Inverted mode Ratio

21 Comparison of the dark current HPK(MPP) vs EEV(inverted) Similar in mV EEV = HPK  1.3 But measured gain EEV = HPK  0.5 Dark current in electrons for CCD’s under our study EEV = HPK  2.5

22 Summary MIP’s are successfully detected using HPK CCD Operation at room temperature ~0ºC –S/N >10 up to +5ºC –efficiency very close to 100% –position resolution: 3.0µm Comparison with EEV CCD –Both “MPP” and “inverted” mode suppress the dark current by one order of magnitude

23 Future prospects Tracking performance of EEV CCD will be examined in June. Radiation damage –affects CTE(Charge Transfer Efficiency) –CTE measurements are on-going. –Irradiation with a strong 90 Sr will take place in the near future.