Amoroso, Antonio

Baldini, R.

Bertani, M.

Bettoni, D.

Bianchi, Fabrizio

Calcaterra, A.

Carassiti, V.

Cerioni, S.

Chai, J.

Cibinetto, G.

Cotto, Giorgio

De Mori, Francesca

Destefanis, Marco Giovanni Maria

Dong, J.

Dong, M.

Farinelli, R.

Fava, L.

Felici, G.

Fioravanti, E.

Garzia, I.

Gatta, M.

Greco, Michela

Hu, Jifeng

Ji, X.

Johansson, T.

Leng, C.

Li, H.

Liu, Z.

Maggiora, Marco

Marcello, Simonetta

Marciniewski, P.

Melchiorri, M.

Mezzadri, G.

Morello, G.

Ouyan, Q.

Pacetti, S.

Patteri, P.

Rivetti, Angelo

Rosner, C.

Savri&#233

Sosio, Stefano

Spataro, Stefano Giovanni

Tskhadadze, E.

Wang, K.

Wang, L.

Wu, L.

Ye, M.

Zallo, A.

Zhang, Y.

Zotti, Laura

English

Institutional Research Information System University of Turin

This full text was downloaded from iris - AperTO: https://iris.unito.it/iris - AperTOUniversity of Turin’s Institutional Research Information System and Open Access Institutional RepositoryThis Accepted Author Manuscript (AAM) is copyrighted and published by Elsevier. It isposted here by agreement between Elsevier and the University of Turin. Changes resultingfrom the publishing process - such as editing, corrections, structural formatting, and otherquality control mechanisms - may not be reflected in this version of the text. The definitiveversion of the text was subsequently published in NUCLEAR INSTRUMENTS &METHODS IN PHYSICS RESEARCH. SECTION A, ACCELERATORS,SPECTROMETERS, DETECTORS AND ASSOCIATED EQUIPMENT, 824, 2015,10.1016/j.nima.2015.11.082.You may download, copy and otherwise use the AAM for non-commercial purposesprovided that your license is limited by the following restrictions:(1) You may use this AAM for non-commercial purposes only under the terms of theCC-BY-NC-ND license.(2) The integrity of the work and identification of the author, copyright owner, andpublisher must be preserved in any copy.(3) You must attribute this AAM in the following format: Creative Commons BY-NC-NDlicense (http://creativecommons.org/licenses/by-nc-nd/4.0/deed.en),10.1016/j.nima.2015.11.082The publisher's version is available at:http://linkinghub.elsevier.com/retrieve/pii/S0168900215014564When citing, please refer to the published version.Link to this full text:http://hdl.handle.net/2318/1636171A Cylindrical GEM Detector with Analog Readout for1the BESIII Experiment2A. Amorosoa,b, R. Baldinic, M. Bertanic, D. Bettonid, F. Bianchia,b,3A. Calcaterrac, V. Carassitid, S. Cerionic, J. Chaia,g, G. Cibinettod,∗, G.4Cottoa,b, F. De Moria,b, M. Destefanisa,b, J.Dongc,g, M.Dongg, R. Farinellid,e,5L. Favaa,b, G. Felicic, E. Fioravantid, I. Garziad, M. Gattac, M. Grecoa,b, J.F.6Hua,b, T. Johanssonh, C. Lenga,g, H. Lia,g, Z. Liug, M. Maggioraa,b, S.7Marcelloa,b, P. Marciniewskih, M. Melchiorrid, G. Mezzadrid,e, G. Morelloc, Q.8Ouyang, S. Pacettif, P. Patteric, A. Rivettia, C. Rosneri, M. Savrie´d,e, S.9Sosioa,b, S. Spataroa,b, E.Tskhadadzej, K. Wangg, L. Wangg, L. Wug, X. Jig,10M. Yeg, A. Zalloc, Y. Zhangg, L. Zottia,b11aNFN-Turin, Italy12bUniversity of Turin, Italy13cLNF-INFN, Frascati, Italy14dINFN-Ferrara, Italy15eUniversity of Ferrara, Italy16fNFN and University of Perugia, Italy17gInstitute of High Energy Physics, Beijing, PRC18hUpsala University, Sweden19iUniversity of Mainz, Germany20jJoint Institute for Nuclear Research, Dubna, Russia21Abstract22A cylindrical GEM detector with analog readout is under development forthe upgrade of the Inner Tracker of the BESIII experiment at IHEP (Bei-jing). The new detector will match the requirements for momentum resolution(σpt/pt ∼ 0.5% at 1 GeV) and radial resolution (σxy ∼ 120µm) of the exist-ing drift chamber and will improve significantly the spatial resolution along thebeam direction (σz ∼ 150µm) with very small material budget (less than 1.5%of X0). With respect to the state of the art the following innovations will bedeployed: a lighter mechanical structure based on Rohacell, a new XV anodereadout plane with jagged strip layout to reduce the parasitic capacitance, andthe use of the analogue readout inside a high intensity magnetic field to havegood spatial resolution without increasing the number of channels.Keywords: Tracking detectors, GEM, Micro-pattern Gas Detectors, BESIII23∗Corresponding authorPreprint submitted to Elsevier July 8, 2015experiment24PACS: 29.40.Cs, 29.40.Gx251. Introduction26The BESIII spectrometer and the BEPCII e+e−collider offer an unique ex-27perimental setup to investigate Particle Physics [1, 2]. The excellent perfor-28mances of the spectrometer and the unprecedented luminosities of BEPCII have29already allowed to collect in the last few years world record statistics at different30center of mass energies in the Charmonium and Open Charm mass range, and31more will come in the next years. BESIII is in fact expected to take data until32at least 2022 and more likely until 2024. Due to the very high BEPCII luminosi-33ties, the current Inner Tracker of the BESIII spectrometer, a drift chamber, is34starting to show aging effects that in few years could affect significantly the de-35tector performance. A possible solution would be to build a new Inner Tracker36(IT) composed of Cylindrical Gas Electron Multiplier (CGEM) detectors.372. The CGEM Project38The new IT will be composed by three layers of triple cylindrical GEM [3, 4];39each layer will be assembled with five cylindrical structures: one cathode, three40GEMs and the anode readout (see Fig. 1). To minimize the material, no sup-41port frames are used inside the active area and the GEM foils are mechanically42stretched being glued to fiberglass rings at their ends.4344Such a detector will match the requirements for momentum resolution (σpt/pt ∼450.5% at 1 GeV) and radial resolution (σxy ∼ 120µm) of the existing drift cham-46ber and will improve significantly the spatial resolution along the beam direction47(σz ∼ 150µm) with very small material budget (less than 1.5% of X0).48A new Rohacell [5] based technique will be adopted to manufacture the anode49and cathode structures in order to minimize the material budget with respect to50the state of the art. Building supports for the sub-layers composed of Rohacell512Figure 1: Cross-section of the triple GEM detector used for the BESIII CGEM-IT.instead of the standard Honeycomb allows to significantly reduce the total radi-52ation length of detector, down to almost 50% compared to equivalent structure53composed of Honeycomb.54The readout anode circuit is manufactured by EST-DEM CERN Workshop55starting from the 5 µm copper clad, 50 µm thick polyimide substrate, the same56used for GEM foils. Two such a foils with copper segmented in strips will be57used to have the two dimensional readout. The strip pitch will be 650 µm,58570 µm wide X-strips are parallel to CGEM axis, providing the rϕ coordinates;59while the V-strips, having a stereo angle with respect to the X-strips, are 13060µm wide and, together with the other view, gives the z coordinate. The stereo61angle depends on the layer geometry. A jagged-strip layout has been developed62to minimize the capacitance couplings: the inter-strip capacitance reduction63w.r.t. the standard strip configuration is about 30%. The anode design has64been studied by means of Maxwell and Garfield simulations and will be tested65on a small-scale planar prototype.6667Due to the relatively strong BESIII magnetic field (1 T), a digital readout elec-68tronic cannot be suitable to match the requirements of the BESIII CGEM-IT.693This would require a high segmentation and a prohibitive number of channels.70Therefore, an innovative readout based on analogue information and data push-71ing architecture will be developed. Analogue readout allows identifying the72charge centroid with a moderate strip pitch (650 µm). While data pushing73architecture allows to move the overall apparatus readout synchronization to74the off-line farms using the time-tag approach. The charge will be measured75by a time-over-threshold technique and the new ASIC chip will be based on76UMC-110nm technology.773. Beam Test on a Planar Prototype78A beam test has been performed at CERN in order to measure the perfor-79mance of a detector GEM prototype suitable for BESIII. The prototype was80instrumented by a XY anode plane, with 650 µm strips, readout by means of81APV25 analog hybrid cards [6]. Tracks were reconstructed with an external82telescope composed by four additional GEM chambers. Efficiency, cluster size83and spatial resolution have been measured with different gas mixtures. Fig. 284reports the tracking efficiency as function of the gas gain with Ar/Isobutane85(90/10) gas mixture; the plateau starts at a gain of about 6000. The efficiency86in the plateau region is above 97%. Spatial resolution has been preliminarily87evaluated from the residual distribution of the test chamber clusters with re-88spect to the reconstructed track; in the plateau region the resolution does not89depend on the gain. Fig. 3 shows the σ of the residual distributions as function90of the gas gain: the average value is about 90 µm. Such preliminary results are91very encouraging, nevertheless a new beam test is required in order to study the92GEM behaviour inside a high magnetic field where the Lorentz force is expected93to distort the electron avalanche.944. Conclusions95We are developing a cylindrical GEM detector with analog readout to up-96grade the BESIII IT. The project has been funded within the Executive Pro-9742000 4000 6000 8000 10000 12000 14000 16000 18000 200006065707580859095100Efficiency (%) vs gain (V)•  X Cluster•  Y Cluster•  X AND YGainEfficiency (%)Figure 2: Efficiency of GEM planar prototype as function of the gas gain.2000 4000 6000 8000 10000 12000 14000 16000 18000 200008090100110120Spatial resolution (micron) vs gain (V)•  X View•  Y ViewGainresolution (µm)Figure 3: Spatial resolution of GEM planar prototype as function of the gas gain.5gramme for Scientific and Technological Cooperation between Italy and P.R.C.98for the years 2013-2015, and and with the acronym BESIIICGEM has been se-99lected as one of the project funded by the European Commission within the call100H2020-MSCA-RISE-2014..101References102[1] The construction of the BESIII experiment, Nuclear Instruments and Meth-103ods in Physics Research A 598 (2009) 711.104[2] Physics at BES-III, arXiv:0809.1869.105[3] F. Sauli, GEM: A new concept for electron amplification in gas detectors,106Nucl. Instrum. Meth. A386 (1997) 531–534.107[4] Progress on large area GEMs, S. Duarte Pinto et al., JINST 4 (2009)108P12009.109[5] http://www.rohacell.com/product/rohacell/ en/about/properties/pages/default.aspx.110[6] M. Raymond et al., The APV25 0.25 m CMOS readout chip for the CMS111tracker, IEEE Nucl. Sci. Symp. Conf. Rec. 2 (2000) 9/113.1126

A cylindrical GEM detector with analog readout for the BESIII experiment

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A cylindrical GEM detector with analog readout for the BESIII experiment

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