AIDA-2020-D15.1 AIDA-2020 Advanced European Infrastructures for Detectors at Accelerators Deliverable Report CERN pixel beam telescope for the PS Dreyling-Eschweiler, J (DESY) et al 25 March 2017 The AIDA-2020 Advanced European Infrastructures for Detectors at Accelerators project has received funding from the European Union s Horizon 2020 Research and Innovation programme under Grant Agreement no. 654168. This work is part of AIDA-2020 Work Package 15: Upgrade of beam and irradiation test infrastructure. The electronic version of this AIDA-2020 Publication is available via the AIDA-2020 web site <http://aida2020.web.cern.ch> or on the CERN Document Server at the following URL: <http://cds.cern.ch/search?p=aida-2020-d15.1> Copyright c CERN for the benefit of the AIDA-2020 Consortium
Grant Agreement No: 654168 AIDA-2020 Advanced European Infrastructures for Detectors at Accelerators Horizon 2020 Research Infrastructures project AIDA -2020 DELIVERABLE REPORT CERN PIXEL BEAM TELESCOPE FOR THE PS DELIVERABLE: 15.1 Document identifier: AIDA-2020-D15.1 Due date of deliverable: End of Month 24 (April 2017) Report release date: 25/03/2017 Work package: Lead beneficiary: WP15: Upgrade of beam and irradiation test infrastructure DESY Document status: Final Abstract: This deliverable report describes the commissioning of the seventh copy of the EUDET-type beam telescope [1]. This seventh copy is called AZALEA. Its overall performance including the performance of the pixel sensors as well as the trigger devices is briefly given. Further details on the hardware components and the timing of this delivery can be found AIDA-2020 Milestone Report Pixel Telescope Hardware Assembled. AIDA-2020 Consortium, 2017 Grant Agreement 654168 PUBLIC 1 / 10
AIDA-2020 Consortium, 2017 For more information on AIDA-2020, its partners and contributors please see www.cern.ch/aida2020 The Advanced European Infrastructures for Detectors at Accelerators (AIDA-2020) project has received funding from the European Union s Horizon 2020 Research and Innovation programme under Grant Agreement no. 654168. AIDA-2020 began in May 2015 and will run for 4 years. Authored by Delivery Slip Name Partner Date J. Dreyling-Eschweiler H. Jansen H. Wilkens DESY DESY CERN 26/02/17 Edited by J. Dreyling-Eschweiler [Task coordinator] DESY 06/03/17 Reviewed by M. Stanitzki [WP coordinator] F. Ravotti [WP coordinator] F. Sefkow [Scientific coordinator] DESY CERN DESY 20/03/17 Approved by Steering Committee 23/03/17 Grant Agreement 654168 PUBLIC 2 / 10
TABLE OF CONTENTS 1. INTRODUCTION... 4 2. COMMISSIONING AT DESY... 5 2.1. MEASUREMENTS IN THE LABORATORY... 5 2.1.1. Sensor characterisation... 5 2.1.2. Dark count test of trigger devices... 6 2.2. TEST BEAM RESULTS... 6 2.2.1. Replacing noisy sensors... 6 2.2.2. Adjusting control voltages of trigger devices... 6 3. COMMISSIONING AT CERN PS... 7 3.1. HIT CORRELATIONS... 7 3.2. RESIDUAL WIDTHS... 7 4. CONCLUSION... 8 REFERENCES... 10 Grant Agreement 654168 PUBLIC 3 / 10
Executive summary This report completes the delivery of the 7th EUDET-type beam telescope. The hardware components and the timing of the delivery are described in the AIDA-2020 Milestone Report Pixel Telescope Hardware Assembled. Here, we focus on the performance of the telescope and its sensors. The characterization of the Mimosa26 sensors is briefly described as well as the performance of the trigger devices. 1. INTRODUCTION Within the AIDA-2020 project, one upgrade task of test beam facilities was to install a beam telescope for CERN PS beam lines. Thus, a seventh copy of the EUDET-type beam telescope [1, 2], called AZALEA, was assembled and installed in September 2016. The hardware components, the timing of purchasing and production, and the assembly phases at DESY II and CERN PS are described in the Milestone Report MS32 [3]. In this report, we focus on the commissioning of the telescope in the laboratory, at the DESY test beam and finally at the CERN PS test beam area. This covers the performance of the Mimosa26 sensors, the trigger devices, and the data acquisition (DAQ) of the entire setup. Grant Agreement 654168 PUBLIC 4 / 10
2. COMMISSIONING AT DESY 2.1. MEASUREMENTS IN THE LABORATORY After the calibration of the sensors (Sec. 2.1.1), the production of the trigger devices (Sec. 2.1.2) and the assembly of all hardware [3], the DAQ system of the telescope was tested in FH E-Lab at DESY (June 2016). Therefore, all six sensor planes were successfully programmed (daisy chained JTAG) in order to run synchronously with a common 80 MHz clock. Using the internal auto-trigger mode with 1 khz of the EUDET Trigger Logic-Unit (TLU) [4] has shown the expected event rate of the DAQ indicating the serviceability of the telescope. 2.1.1. Sensor characterisation To operate the Mimosa26 sensors at a chosen threshold in terms of noise, every sensor has to be characterised [5]. The characterization requires scanning the threshold voltages for each of the 4 sub-arrays of each sensor and measuring the active pixels of these binary sensors. The expected result of this transfer function is shown in Fig. 1a. A noisy sub-array is shown in Fig. 1b, which necessitate a replacement in order to ensure a proper performance for track finding (Sec. 2.2.1). Figure 1: The transfer function of a sub-array (288x576 pixels) of a Mimosa26 sensor. Each colour represents a pixel, and each data point is the mean out of 1000 measurements for a certain threshold voltage. Left: (a) Sub-array C of sensor 101 shows the expected performance having most of the pixels around the 0 mv value (middle point). The second bunch around -5 mv is due to the substructure of the Mimosa26. Right: (b) Sub-array C of sensor 104 shows that some pixels are always active due to the horizontal line even for high threshold voltages. The analysis provided in the total noise of each sensor, which is defined as the quadratic sum of the temporal noise and the fixed pattern noise. This is given in the following for each sensor: Plane 0: Sensor ID 101: σ = 1.068 mv Plane 1: Sensor ID 102: σ = 1.068 mv Plane 2: Sensor ID 103: σ = 1.067 mv Plane 3: Sensor ID 104: σ = 1.055 mv (including one deactivated column and one row of hot pixels) Plane 4: Sensor ID 105: σ = 0.981 mv Grant Agreement 654168 PUBLIC 5 / 10
Plane 5: Sensor ID 106: σ = 1.084 mv (including one row of hot pixels) Furthermore, according to the results individual JTAG files are created for thresholds from 3 to 12. These files are available for the user in order to operate the telescope. 2.1.2. Dark count test of trigger devices After mounting the scintillator to the PMT, the whole unit is wrapped with 2-3 layers of black tape to shield the device against environmental light. Each trigger device was operated at a standard control voltage of 800 mv, and the signal output was connected to an oscilloscope. By shining light directly on the device and setting a trigger level to -40 mv (due to negative pulses), the dark count rate was estimated. A sufficient light tightness was concluded as the dark count rate was found to be << 1 count per second, which is close to the cosmic rate. 2.2. TEST BEAM RESULTS After the successful baseline test in the laboratory, the telescope was set up in the test beam area 22 in 4 th /5 th of July 2016. Here the functionality of the trigger-driven event building of the telescope s DAQ was confirmed using an electron beam and the 4 trigger devices in coincidence. According to the first test beam, optimizations for the sensors (Sec. 2.2.1) and the trigger devices (Sec. 2.2.2) were performed 2.2.1. Replacing noisy sensors Although hot pixels can be excluded by the track reconstruction used in the EUTelescope software, they slow down the total analysis process and create significantly larger files. Thus, the two noisy sensors 104 and 106 were exchanged with sensors having no column or row with hot pixels (see Sec. 2.1.1). Accordingly, the JTAG files were updated. This is the final arrangement of the six Mimosa26 sensors for the AZALEA beam telescope: Plane 0: Sensor ID 101: σ = 1.068 mv Plane 1: Sensor ID 102: σ = 1.068 mv Plane 2: Sensor ID 103: σ = 1.067 mv Plane 3: Sensor ID 6b: σ = 1.015 mv Plane 4: Sensor ID 105: σ = 0.098 mv Plane 5: Sensor ID 69: σ = 1.061 mv JTAG files are stored online on GitHub [6]. 2.2.2. Adjusting control voltages of trigger devices The control voltage of each PMT was optimized subsequently by measuring the coincidence rate of the 4 trigger devices. The identification of the lowest control voltage, which does not show a further increase of the coincidence rate, was performed by setting a trigger level of -40 mv and scanning the control voltage in steps of 25 mv. In Table 1, the final arrangement of the trigger devices including the proper PMT control voltage is shown. Grant Agreement 654168 PUBLIC 6 / 10
Dev. # Scintillator geometry, width [cm] x length [cm] PMT H11901-110 Serial No. Control Voltage [mv] 0 vertical, 2 x 1 A0720019 800 1 horizontal, 1 x 2 A0720017 800 2 horizontal, 1 x 2 A0720018 800 3 vertical, 2 x 1 A0720020 850 Table 1: Trigger devices for the AZALEA telescope. 3. COMMISSIONING AT CERN PS After the transport to CERN and the installation in PS T10 [3], all commissioning tests were repeated without any problems at a beam energy of 5 GeV. 3.1. HIT CORRELATIONS The correlation plots provided by the Online Monitor of EUDAQ v1.6 [1] indicated that the telescope was aligned in respect to the particle tracks of the PS test beam. In Figure 2, two exemplary correlations are shown. In both plots, the diagonal line indicates sensor hits generated by particles; horizontal and vertical lines indicate single noisy pixels. The thickness of the diagonal line depends on the beam spread, which is more distinctive for the right plot, since more scattering material is traversed when particle induce hits on the telescope plane 5. Figure 2: Both plots show the correlation of hits projected to the row-axis of a sensor, thus, the x- and y-axis represent a 576 columns of a sensor. The hit frequency is given by the colour map, which is given in a logarithmic scale. On the left, the correlation between telescope plane 0 and 1 is given, on the right, between plane 0 and the last plane 5. 3.2. RESIDUAL WIDTHS One data set using the CERN PS T10 beam was analysed using EUTelescope [1]. As a figure of merit, the biased residual distribution, which includes the hit information of all 6 planes for track reconstruction, was calculated for each telescope plane along the x- and y-axis. The residual of a track is the distance between the measured hit and the biased track fit and depends on the intrinsic sensor resolution, the telescope geometry, the amount of material budget and the beam energy [1]. In Figure 3, the biased residual resolution is shown resulting from a general Grant Agreement 654168 PUBLIC 7 / 10
broken line (GBL) [7,8] track fit which includes correction for multiple scattering for particle tracks and was already applied for the performance analysis of EUDET-type telescopes [1]. The width, which is given as a RMS value here, is similar to the results of the detailed performance analysis [1]. Figure 3: As an example, the biased residual distribution is plotted for telescope plane 0, on the left for the x-direction (sensor rows), on the right for the y- direction (sensor columns). In Table 2, RMS values for all telescope planes are given. The results are comparable with the results from [1]. Plane No. res. width (RMS) in x [μm] res. width (RMS) in y [μm] 0 3.16 3.10 1 3.36 3.35 2 3.75 3.76 3 3.77 3.76 4 3.38 3.39 5 3.22 3.23 Table 2: Biased residuals widths (RMS) of an exemplary PS run using the AZALEA telescope. 4. CONCLUSION The AZALEA beam telescope was successfully delivered to CERN PS beam line T10 [3], see Figure 4. The telescope performance shows expected results and is comparable to the performance of the DATURA telescope, which represents EUDET type telescopes [1]. Finally, the most important steps to operate and maintain these devices can be found in a technical note [9]. Grant Agreement 654168 PUBLIC 8 / 10
Fig. 4: Top: In front of T10 at CERN PS, the yellow control hut on the right. Bottom: The telescope hardware in the beam line of T10. Grant Agreement 654168 PUBLIC 9 / 10
REFERENCES [1] Jansen, H. et al. (2016), Performance of the EUDET-type beam telescopes, EPJ Techniques and Instrumentation 20163:7, DOI: 10.1140/epjti/s40485-016-0033-2 [2] Dreyling-Eschweiler, J. et al. (2016), EUDET-type beam telescopes [online], https://telescopes.desy.de/ [Accessed: 1 February 2017]. [3] Dreyling-Eschweiler, J. et al. (2016), Pixel telescope hardware assembled, AIDA2020 Milestone Report MS32, https://cds.cern.ch/record/2228501 [4] Cussans, D., (2009), Description of the JRA1 Trigger Logic Unit (TLU), v0.2c, Tech. Rep. EUDET-Memo-2009-04 http://www.eudet.org/e26/e28/e42441/e57298/eudet-memo-2009-04.pdf [5] Hu-Guo C, et al (2010), First reticule size MAPS with digital output and integrated zero suppression for the EUDET-JRA1 beam telescope, Nucl Instrum Methods Phys Rev A 623(1): 480 482. 1st International Conference on Technology and Instrumentation in Particle Physics. [6] Dreyling-Eschweiler, J. et al. (2016), Mimosa26 JTAG files, GitHub online repository https://github.com/eudaq/eudaq-configuration/tree/master/azalea/jtag_azalea [Accessed: 1 February 2017]. [7] Blobel V, Kleinwort C, Meier F (2011), Fast alignment of a complex tracking detector using advanced track models, Comput Phys Commun 182(9): 1760 1763. Computer Physics Communications Special Edition for Conference on Computational Physics Trondheim, Norway, June 23 26, 2010. [8] Kleinwort C (2012), General broken lines as advanced track fitting method, Nucl Instr Meth Phys Res A 673: 107 110. [9] Dreyling-Eschweiler, J. and Jansen, H. (2017), Checklists for using and maintaining EUDET beam telescopes, AIDA-2020-Note-2017-003, http://cds.cern.ch/record/2254682 Grant Agreement 654168 PUBLIC 10 / 10