Silicon Drift Detectors for the kaonic atom X-ray measurements in the SIDDHARTA experiment

1. Silicon Drift Detectors for the kaonic atom X-ray measurements in the SIDDHARTA experiment T. Ishiwatari Stefan Meyer Institut, Vienna, Austria SIDDHARTA Collaboration Silicon Drift Detector for Hadronic Atom Research by Timing Applications LNF- INFN, Frascati, Italy Stefan Meyer Institut, Vienna, Austria Politecnico, Milano, Italy MPE, Garching, Germany PNSensors, Munich, Germany IFIN – HH, Bucharest, Romania Univ. Victoria, Canada RIKEN, Japan The 11th VCI 2007 Feb 19-24,2007

2. 1. Kaonic atom X-rays 2. Kaonic hydrogen with CCDs (DEAR, LNF) 3. Silicon Drift Detectors 4. Kaonic helium with SDDs (E570,KEK) 5. Kaonic hydrogen & deuterium with SDDs by Monte Carlo (SIDDHARTA, LNF) Silicon Drift Detectors for the kaonic atom X-ray measurements in the SIDDHARTA experiment

3. Shift (e) and width (G) of K-p and K-d gives isospin dependent KN scattering lengths(a0and a1) Kaonic atom X-rays and KN scattering lengths Difficulty 1. High-background in kaon beams 2.Small X-ray yields (a few% K-p, below 1% K-d) 3.Precise determination of X-ray energy and width X-ray detector with 1. high background rejection, 2. large-area, 3. good resolution in energy and time These scattering lengths provide Low-energy SU(3) QCD: SU(3) chiral symmetry, KN s-term, nature ofL(1405), S0 ( 3115 ) S + (3140)

4. KpX DEAR Iwasaki et al, 1997 -500 0 500 Experimental results of kaonic atoms Results of kaonic hydrogen repulsive attractive 1000 800 600 width G1s [eV] Izycki et al, 1980 400 Accuracy for K-p, First for K-d (as well as 4He,3He) are badly needed! 200 Bird 1983 Davies 0 shift e1s [eV] Phys. Rev. Lett. 94, 212302 (2005)

5. DEAR DEAR experiment at DAFNE DAFNE e+e- collider optimized to produce f-meson at rest (1.020 GeV) • K- beam at DAFNE • Monochromatic • Low-energy • No hadronic background

6. DEAR experimental setup APD Cryo-Cooler Kaon Monitor TMP CryoTiger CCD Cooling CCD Electronics Vacuum Chamber CCD Pre-Amplifier CCD55-Chips • 16 CCD55-30 (EEV) • 1242 x 1152 pixels • pixel size 22.5 x 22.5 mm • total area 7.24 cm2 per chip • depletion depth ~30 mm • read-out time 1 min. • energy resolution ~150 eV @ 6keV • temperature at 165 K

7. X-rays CCD X-ray detector X-ray events 1 and 2 pixel events Charged particles  large pixel events background suppression by pixel analysis

8. NIMA 556(2006)509 X-ray events S/N~1:70 Parts of MIPs ~1,2 pixels X-rays : 1,2 pixels MIPs :~ 8 pixels, Some MIPs: ~ 1,2 pixels background events on X-ray spectra Timing needed! K-p energy spectrum by DEAR CCDs PRL 94, 212302 (2005) DEAR results 1s = - 193 ± 37 (stat.) ± 6 (syst.) eV 1s = 249 ± 111 (stat.) ± 30 (syst.) eV

9. electrode type Si(Li) SDD anode cathode SDD (Silicon Drift Detector) X-ray detector small anode  large-area, high energy resolution, Thin depletion  reduce background caused by electron/gamma Low capacitance Q = CV = (ε0S / d ) V

10. Comparison of X-ray detectors used for kaonic X-ray experiments SDD Si(Li) These values are obtained during the beam times.

11. Kaonic Helium X-rays with SDDs (E570, KEK) K-4He La X-rays KETEK 1 cm2 SDD

12. 3) Reconstruction of K and charged particles 1) 8 Silicon Drift Detectors “SDDs” E570 experimental setup Drift chamber (PDC,VDC) Charged particles K- X-ray BDC LHe target

13. 104 times less Kaonic 4He Energy spectra with SDDs Self trigger KHe 3-2 KHe 4-2 Counts/30 eV KHe 5-2 Ti Ka Events from target cell Ni Ka

14. SIDDHARTA experiment (LNF, Italy) Silicon Drift Detectors for Hadronic Atom Research by Timing Application New SDDs specially designed for SIDDHARTA 200 SDDs with 1cm2 per SDD on-chip preamp

15. K+ K- F Φ K+ + K- X-ray Triple coincidence technique e+ Triple coincidence: SDDX * ScintK * ScintK Scintillator SDD Target Scintillator e- S/N =1:70 (CCD)10:1 (SDD) for kaonic Hydrogen

16. Temperature 22 K Pressure max. 5 bar 200 SDDs with 1cm2 per SDD Side wall: Kapton 75 µm Kaon entrance Window: Kapton 150 mm

17. SDDs electronics Cryogenic target cell Kaon entrance window

18. Background suppression >103 Monte Carlo for SIDDHARTA W/o coincidence MIPs (e+/e-) in SDD Kaon decays With coincidence of K+, K-, X-ray Energy (keV) Signal rate ~ 2.2x10-3 /s 130 /d (duty cycle=2/3 of d.)

19. Energy spectra in SIDDHARTA (Monte Carlo) Kaonic deutrium Kaonic hydrogen S/N=1:1 Kβ Kα S/N=10:1 Kg, ... Energy (keV) K-p: ε1s = 193 eV, Γ1s = 249 eV, Y(Kα)=2% precision: ε1s± 3 eV Γ1s± 5 eV K-d: ε1s = 325 eV, Γ1s = 630 eV, Y(Kα)=0.2% precision: ε1s± 18 eV Γ1s± 45 eV Signal rate ~ 2.2x10-3 /s 130 /d (duty cycle=2/3 of d.) 30 days data taking

20. Summary • Application of SDD X-ray detectors in the field • of kaonic atoms is given. • SDDs have good Energy resolution as well as good Time resolution. • Prototype of Large-area SDDs are tested with a kaon beam at • KEK successfully. • High performance on Energy resolution, Time resolution, • Background rejection capability was measured. • We are now developing new type of Large-area SDDs specially • designed for SIDDHARATA experiment. • SIDDHATA will obtain • the most accurate for kaonic hydrogen X-rays, • and the first observation of kaonic deuterium X-rays. • The physics runs start from 2007. Part of the work was supported by "Transnational Access to Research Infrastructure" (TARI), HadronPhysics I3, Contract No. RII3-CT-2004-506078.

21. Silicon Drift Detector electrode type Q = CV = (eS / d ) V Si(Li) SDD anode cathode Small capacitance UBACK high energy resolution at fast shaping times, due to the small anode capacitance GND UIR UOR

22. 3) Reconstruction of K and charged particles 2) Ti and Ni foils p-(or K-) 1) 8 Silicon Drift Detectors “SDDs” E570 experimental setup Drift chamber Charged particles K- Ti,Ni X-rays X-ray Scint LHe target