First results from prototype measurements Susanna Costanza Pavia Group & IKP-Jülich PANDA Collaboration Meeting, GSI – 9 Mar 2010

S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010 Outline 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 S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010

S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010 STT prototype @ FZJ Designed for COSY-TOF and PANDA (P. Wintz) ELECTRONICS: Standard existing electronics 64 channels with CMP16 + F1-TDC 64 channels with Fast QDC (160 MHz, 240 MHz in prep) from WASA @ COSY S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010 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 (ArCO2 (90/10) - ArC2H6 (80/20)) Operating at overpressure

STT prototype @ FZJ (III) Aim: Measurement of particle energy losses Construction of dE/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, …) Beta particles from Sr source ArCO2 (90/10) 16 tubes S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010 Sr90 radioattivo, decade beta con decay energy = 0.546 MeV s < 15 % K. Pysz, H. Ohm, V. Serdyuk, P. Kulessa, P. Wintz PANDA Collaboration Meeting @ FZJ – Sept 2009

Aim of the present work: First results for dE/dx are already promising Deeper investigation of these data 2 different readout information: TDC and QDC Work packages: calibration of the straw (position and isochrone parametrization) reconstruction of cosmic tracks dE/dx analysis using full QDC information (time signal, signal amplitude and integrated charge) track length information in the gas Data sets: ArCO2 (90/10) ArC2H6 (80/20) Comparison between TDC and QDC information i.e. isochrone parametrization S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010 Sr90 radioattivo, decade beta con decay energy = 0.546 MeV

S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010 Typical TDC spectrum 1 tube with TDC ArCO2 (90/10) 1 bar overpressure 1700 V S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010

S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010 From TDC spectra… Conversion TDC counts  ns Fitting of the single spectra Offset correction for single spectra Sum of all the spectra 1 ch = 0.130 ns ATLAS Coll., NIM A 523 (2004) P1: uncorrelated noise P3 & P4: describe the spectrum shape P5: t0 P6: tmax P7: slope of the leading edge P8: slope of the trailing edge S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010 fit t0, tmax Noise level

… to isochrone calibration r-t relation obtained in the hypotesis of uniform illumination over the tube volume: 3rd order polynomium p0 1.824190 e-01 p1 6.377422 e-02 p2 -3.092456 e-04 p3 5.535298 e-07 S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010

Tracking method PREFIT: minimization of the perpendicular distances of a set of N points (xi, yi) from the best-fit line The function to be minimized is: where (xi, yi) = centres of the firing tubes S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010 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:

S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010 Tracking method (II) FILTERING after the prefit: 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 MINUIT FIT: Fit of the following c2: where: are the residuals are the drift radii obtained from the r-t relation previously derived S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010 FILTERING after the Minuit fit: Filter for spurious hits: cut on the residual value

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

Mean residuals distribution PRELIMINARY RESULTS!!! Just 1 iteration m = 25.86 mm s = 187.5 mm S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010

Residual distributions in single intervals s = 143.7 mm S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010 s = 152.5 mm

S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010 Resolution curve Data Fit PRELIMINARY RESULTS!!! Just 1 iteration S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010

S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010 Summary & Outlook 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 (CMP16) Track length correction to be used in dE/dx analyses Set up the QDC analyses Determine the dE/dx resolution Compare different data sets Comparison of experimental results with simulations S. Costanza PANDA Collaboration Meeting – GSI, 9/03/2010 Thank you!