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SIDDHARTA Status Report: Recent Results, Data Analysis, and Outlook

This report provides an overview of the work done by the SIDDHARTA collaboration, including the rebuilding of SDDS mounts, replacement of SDD modules, and improvement of shielding. It also discusses recent results in Kaonic Helium and data analysis.

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SIDDHARTA Status Report: Recent Results, Data Analysis, and Outlook

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  1. SIDDHARTA: Status report   Michael Cargnelli Stefan Meyer Institute Austrian Academy of Sciences, Vienna Work supported by TARI-INFN Contract No. RII3-CT-2004-506078 On behalf of: The SIDDHARTA collaboration Garching Munich Vienna Bucarest 39th Meeting of the LNF Scientific commitee, 26-27 Oct 2009

  2. Content  Reminder Siddharta from installation untill the last Scientific Commitee Work done since last Sci. Com. rebuilding of the sdds mounts replacement of sdd modules new upper kaon detector improved shielding Recent results Kaonic Helium publication 1 accepted by PRB Accumulated data Data analysis general Signal and Signal-to-background improvement hydrogen spectrum deuterium helium first shift and width analysis Summary Outlook 2

  3. New X-ray detectors (SDD silicon drift detectors) timing capability  background suppression by using the kaon - X ray time correlation excellent energy resolution high efficiency, large solid angle performance in accelerator environment SIDDHARTA - What is it ? Goal: measure the shift and broadening of the X ray transition of kaonic atoms. The ground state is affected by the strong interaction of the kaon and the nucleus. Delivers input for effective theories in low energy QCD SDDs SDDs X K- Scint F e+ e- Scint Triple coincidence: SDDX * ScintK * ScintK K+ E (2-1) el.mag. = 6.480 keV 3

  4. From installation untill the last Scientific Commitee Installation of the setup at DAFNE (including shielding) Tests and debug: (in parallel with the DAFNE restart), calibration study, trigger tests Degrader optimization by measurement of kaonic helium-4 In-beam calibration procedure – sliding mechanism (exchange degrader vs. calibration foil), stability test Study of systematic errors using a Fe-55 source inside the setup, data for KHe publication 1 Hydrogen filled, KH measurement started Sept. 2008 2009 March 38 Sci.Com May 2009 4

  5. Since May: setup improvements during summer shutdown - rebuilding of the sdds mounts: gain of solid angle of X ray detectors - replacement of sdd modules: 144 cm2 detectors operational - new upper kaon detector: less material in vicinity of target, clean trigger - improved shielding: new multimaterial and more narrow collimator 5

  6. Collimator 6

  7. Collimator old new 7

  8. Shielding around target old new 8

  9. Shielding around beam pipe old new these pieces were removed, could be radiation sources visible from target 9

  10. Kaon trigger tdc3 adc3 kaons dE > 3 MeV mips: dE ~ 100 keV tdc1 adc1 kaon trigger scintillators v.3 new small scintillator (tdc3+4)/2 meantime up low adc thresholds to cut mips, leave kaons tdc4 adc4 tdc start = DAFNE bunch frequency / 2 adc3,4 geom. mean tdc2 adc2 TOF kaons kaons (tdc1-tdc2) = PosA 900 ps mips mips (tdc3-tdc4) = PosB (tdc1+2+3+4) / 4. 10

  11. Recent results - Kaonic Helium publication accepted (confirming the KEK E570 result using a gaseous target - 2nd KHe publication concerning yields of the transitions under preparation 11

  12. Luminosity siddharta can work only between injections (blue dots, yellow line) under good conditions during siddharta DAQ ~ 2.8e32 – 1.0e32 cm-2 s-1 luminosity compare to 2002 DEAR experiment: ~ 3.0e31 cm-2 s-1 now up to 10 times higher ! siddharta integrated luminosity on 23 Oct 2009: ~ 8 pb-1 ! calibration 12

  13. Accumulated data After summershutdown the experimentel apparatus and DAFNE work very fine, we hope to acquire in the remaining time (until 9 Nov) additional data from >100 pb-1 Please note that 100 pb-1 in setup 2 configuration is much more valuable then data before the change. We plan to dedicate ~10 pb-1 to a measurement of K3He which was never measured before and is important for a comparison with the 4He data. 1 siddharta in total ~ 1.5 TB data stored 13

  14. Data analysis What the Data Aquisition System stores: - Energies and detector numbers of X ray hits - event id-number, time-tag if a kaontrigger happend: - the time correlation between X-ray and kaon - the kaon detector parameters - DAFNE current values From this we can derive in off-line analysis: - the kaondetector TOF to discriminate against MIPS - kaondetector position information from the timedifference of the PMs at both ends - sdd rates (e.g. counts during last second) - kaon rates ( -- „ --) - number of hits without vs. hits with kaon coincidence - multiplicity of hits - kaons per Xray Analysis task: select cuts on above listed parameters periodically update calibration and selection of best sdds 14

  15. Kaonic Helium, no Fe-55 source KHe used for gasstop optimization + physics interest1) Calibration: periodic xray-tube switch on during beam Ti + Cu Ka lines transition energy events (3-2) 6.464 1047 ± 37 (4-2) 8.722 154 ± 21 (5-2) 9.767 91.8 ± 19 (6-2) 10.333 82.4 ± 25 higher < 11.63 131 ± 41 KHe (3-2) p r e l i m i n a r y Counts / bin KC (5-4) KHe (4-2) Ti Ka KC (6-5) KHe (5-2) KAl (7-8) KHe Lhigh KC (6-4) KN (5-4) 1) compare KEK E570 KHe L lines in liquid He, consistent result, first measurement in gas X ray energy (keV) 15

  16. Signal- and S/B- improvement ! setup 1 kaon-X time window KHe La accidental background kaonic Helium, normalized for equal luminosity setup 2, after summer shutdown KHe La accidental background 16

  17. untriggered background spectrum, setup 1 and 2 Ti Ka setup 1 Au Lb Cu Ka Au La Pb Lb Ti Ka Cu Ka Au Lb Au La Pb Lb setup 2 normalized for equal luminosity background reduction due to improved shielding + DAFNE optimisation energy (keV) 17

  18. kaonic hydrogen – data since 12 October KH KC (5-4) Ti Ka Region of kaonic hydrogen lines KC (6-5) KO (6-5) previous exp. e 200-320 eV G 250-410 eV KC (7-5) KN (5-4) Pb Lb Pb La KC (6-4) KAl (6-4) 18

  19. kaonic deuterium KD positions KC (5-4) expectation: e ~ 0.7 keV G ~ 1.2 keV Region of kaonic hydrogen lines Ti Ka KO (6-5) KC (6-5) KO (7-6) KN (6-5) Ti Kb KC (7-5) Cu Ka KN (5-4) KC (6-4) KAl (6-4) expected KD pattern 19

  20. kaonic hydrogen fit from the kaonic hydrogen spectrum the KD specturm was subtracted to get rid of the kaonic background lines KO, KN. 290 pb-1 KH For the signal 8 voigtians with given gauss resolution and free identical lorentz width are used for (2-1),.. (9-1) The position pattern is fixed by the QED values. The intensities of (2-1),(3-1) and (4-1) are free, those of the higher transitions are coupledmaccording to theoretical expectatuions (cascade calculation, e.g. Koike) KH (4-1),.. (9-1) KH (2-1) KH (3-1) p r e l i m i n a r y Note: Khigh yield pattern energy (keV) In the final analysis the backgound can be determined from fitting the KD data and then include the pattren in the KH fit.

  21. Summary SIDDHARTA well under way.beam time NOW, until 9 November 2009 K-p considerably higher precisionthen in DEAR expected K-d first measurement ever, exploratory measurement

  22. Outlook In case we might get kaons again (in FINUDA pit, with KLOE in place?) We are ready for a siddharta-2 ! .. our SDDs proved their ability. .. we have learned a lot during the experiment .. have ideas how to further reduce the background Remeasure deuterium other light kaonic atoms 22

  23. We want to expess our special Thanks ! to: Director of LNF, Mario Calvetti DAFNE machine staff G. Corradi, D. Tagnani (Electronics group) B. Dulach, C. Capoccia, Mechanical design, installation Staff of the mechanical workshop, M.A. Franceschini, G. Bisogni 23

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