FIRST RESULTS FROM PROTOTYPE MEASUREMENTS Susanna Costanza Pavia

FIRST RESULTS FROM PROTOTYPE MEASUREMENTS Susanna Costanza Pavia Group & IKP-Jülich PANDA Collaboration Meeting, GSI – 9 Mar 2010

Outline S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010 Description of the experimental setup Aim of this work TDC spectra analysis Tracking method steps Results – Mean residuals distribution – Residuals in dr intervals – Resolution curve • Summary & Outlook • • •

STT prototype @ FZJ Designed for COSY-TOF and PANDA (P. Wintz) DESIGN 4 x (16 x 2) = 128 straws (4 self-supporting double-layers, 32 tubes each) 1. 5 m long 30 mm wall thickness (aluminised mylar) 20 mm anode wire Different gas mixtures (Ar. CO 2 (90/10) - Ar. C 2 H 6 (80/20)) Operating at overpressure PANDA Collaboration Meeting – GSI, 9/03/2010 Standard existing electronics 64 channels with CMP 16 + F 1 -TDC 64 channels with Fast QDC (160 MHz, 240 MHz in prep) from WASA @ COSY S. Costanza ELECTRONICS: ELECTRONICS

STT prototype @ FZJ (III) Aim: Ar. CO 2 (90/10) 16 tubes s < 15 % K. Pysz, Pysz H. Ohm, V. Serdyuk, P. Kulessa, P. Wintz PANDA Collaboration Meeting @ FZJ – Sept 2009 PANDA Collaboration Meeting – GSI, 9/03/2010 Beta particles from Sr source S. Costanza Measurement of particle energy losses Construction of d. E/dx curves Experimental check of the achievable energy resolution for the PANDA STT Hints for optimal selection of the final read-out electronics for STT Knowledge about “environmental” conditions (noise suppression, pressure stability, …)

Aim of the present work: S. Costanza First results for d. E/dx are already promising Deeper investigation of these data 2 different readout information: TDC and QDC Data sets: Ar. CO 2 (90/10) Ar. C 2 H 6 (80/20) Comparison between TDC and QDC information i. e. isochrone parametrization PANDA Collaboration Meeting – GSI, 9/03/2010 Work packages: calibration of the straw (position and isochrone parametrization) reconstruction of cosmic tracks d. E/dx analysis using full QDC information (time signal, signal amplitude and integrated charge) track length information in the gas

Typical TDC spectrum S. Costanza 1 tube with TDC Ar. CO 2 (90/10) 1 bar overpressure 1700 V PANDA Collaboration Meeting – GSI, 9/03/2010

From TDC spectra… 1 ch = 0. 130 ns ATLAS Coll. , NIM A 523 (2004) Offset correction for single spectra Sum of all the spectra PANDA Collaboration Meeting – GSI, 9/03/2010 P 1: uncorrelated noise P 3 & P 4: describe the spectrum shape P 5: t 0 P 6: tmax P 7: slope of the leading edge P 8: slope of the trailing edge S. Costanza Conversion TDC counts ns Fitting of the single spectra

… to isochrone calibration r-t relation obtained in the hypotesis of uniform illumination over the tube volume: S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010 3 rd order polynomium p 0 1. 824190 e-01 p 1 6. 377422 e-02 p 2 -3. 092456 e-04 p 3 5. 535298 e-07

Tracking method PREFIT: S. Costanza minimization of the perpendicular distances of a set of N points (xi, yi) from the best-fit line The function to be minimized is: Since the absolute value function does not have continuous derivatives, minimizing R is not amenable to analytic solution. The square of the perpendicular distances is minimized instead: PANDA Collaboration Meeting – GSI, 9/03/2010 where (xi, yi) = centres of the firing tubes

Tracking method (II) FILTERING after the prefit: Fit of the following c 2: where: are the residuals are the drift radii obtained from the r-t relation previously derived FILTERING after the Minuit fit: Filter for spurious hits: cut on the residual value PANDA Collaboration Meeting – GSI, 9/03/2010 MINUIT FIT: S. Costanza Filter for bad events: Cut on the number of hits (5 minimum required) Cut on the mean distance of the centres of the firing tubes to the prefit line Filter for spurious hits: cut on the distance from the prefit

From the event. Display… S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010

Mean residuals distribution S. Costanza ! ! ! S m = 25. 86 mm s = 187. 5 mm PANDA Collaboration Meeting – GSI, 9/03/2010 T L U S E on R Y ati R A ter N I 1 i IM st L E Ju R P

Residual distributions in single intervals S. Costanza s = 143. 7 mm PANDA Collaboration Meeting – GSI, 9/03/2010 s = 152. 5 mm

Resolution curve Data Fit ! ! ! S PANDA Collaboration Meeting – GSI, 9/03/2010 T L U S E on R Y ati R r A e t IN 1 i IM st L E Ju R P S. Costanza §

Summary & Outlook Thank you! PANDA Collaboration Meeting – GSI, 9/03/2010 • • • Track length correction to be used in d. E/dx analyses Set up the QDC analyses Determine the d. E/dx resolution Compare different data sets Comparison of experimental results with simulations S. Costanza Isochrone calibration from TDC spectra Track reconstruction implemented Preliminary mean resolution of ~ 190 mm already after the first iteration With non-dedicated time resolution readout (CMP 16)