002919248 001__ 2919248
002919248 005__ 20241211041835.0
002919248 0248_ $$aoai:cds.cern.ch:2919248$$pcerncds:FULLTEXT$$pcerncds:CERN:FULLTEXT$$pcerncds:CERN
002919248 037__ $$9arXiv$$aarXiv:2412.04686$$cphysics.ins-det
002919248 035__ $$9arXiv$$aoai:arXiv.org:2412.04686
002919248 035__ $$9Inspire$$aoai:inspirehep.net:2856801$$d2024-12-10T20:07:45Z$$h2024-12-11T03:00:29Z$$mmarcxml$$ttrue$$uhttps://inspirehep.net/api/oai2d
002919248 035__ $$9Inspire$$a2856801
002919248 041__ $$aeng
002919248 100__ $$aKoch, Simon Florian$$uOxford U.$$vDepartment of Physics, Oxford University, Oxford, UK.
002919248 245__ $$9arXiv$$aMeasuring the ATLAS ITk Pixel Detector Material via Multiple Scattering of Positrons at the CERN PS
002919248 269__ $$c2024-12-05
002919248 300__ $$a12 p
002919248 500__ $$9arXiv$$a12 pages, 12 figures
002919248 520__ $$9arXiv$$aThe ITk is a new silicon tracker for the ATLAS experiment designed to increase detector resolution, readout capacity, and radiation hardness, in preparation for the larger number of simultaneous proton-proton interactions at the High Luminosity LHC. This paper presents the first direct measurement of the material budget of an ATLAS ITk pixel module, performed at a testbeam at the CERN Proton Synchrotron via the multiple scattering of low energy positrons within the module volume. Using a four plane telescope of thin monolithic pixel detectors from the MALTA collaboration, scattering datasets were recorded at a beam energy of $1.2\,\text{GeV}$. Kink angle distributions were extracted from tracks derived with and without information from the ITk pixel module, and were fit to extract the RMS scattering angle, which was converted to a fractional radiation length $x/X_0$. The average $x/X_0$ across the module was measured as $[0.89 \pm 0.01 \text{ (resolution)} \pm 0.01 \text{ (subtraction)} \pm 0.08 \text{ (beam momentum band)}]\%$, which agrees within uncertainties with an estimate of $0.88\%$ derived from material component expectations.
002919248 541__ $$aarXiv$$chepcrawl$$d2024-12-09T04:03:18.343428$$e8596240
002919248 540__ $$3preprint$$aCC BY 4.0$$uhttp://creativecommons.org/licenses/by/4.0/
002919248 65017 $$2arXiv$$ahep-ex
002919248 65017 $$2SzGeCERN$$aParticle Physics - Experiment
002919248 65017 $$2arXiv$$aphysics.ins-det
002919248 65017 $$2SzGeCERN$$aDetectors and Experimental Techniques
002919248 690C_ $$aCERN
002919248 690C_ $$aPREPRINT
002919248 693__ $$aCERN PS
002919248 693__ $$aCERN LHC$$eATLAS
002919248 700__ $$aMoser, [email protected]$$uCERN$$uOxford U.$$vDepartment of Physics, Oxford University, Oxford, UK.$$vCERN, Geneva, Switzerland.
002919248 700__ $$aLindner, Antonín$$uCERN$$vCERN, Geneva, Switzerland.
002919248 700__ $$aDao, Valerio$$uCERN$$uSUNY, Stony Brook$$vDepartments of Physics and Astronomy, Stony Brook University, Stony Brook, NY, USA.$$vCERN, Geneva, Switzerland.
002919248 700__ $$aAsensi, Ignacio$$uCERN$$vCERN, Geneva, Switzerland.
002919248 700__ $$aBortoletto, Daniela$$uOxford U.$$vDepartment of Physics, Oxford University, Oxford, UK.
002919248 700__ $$aBrekkum, Marianne$$uCERN$$vCERN, Geneva, Switzerland.
002919248 700__ $$aDachs, Florian$$uCERN$$vCERN, Geneva, Switzerland.
002919248 700__ $$aJoos, Hans Ludwig$$uCERN$$uGottingen U., II. Phys. Inst.$$vCERN, Geneva, Switzerland.$$vII. Physikalisches Institut, Georg-August-Universität Göttingen, Göttingen, Germany.
002919248 700__ $$avan Rijnbach, Milou$$uCERN$$uOslo U.$$vCERN, Geneva, Switzerland.$$vDepartment of Physics, University of Oslo, Oslo, Norway.
002919248 700__ $$aSharma, Abhishek$$uCERN$$vCERN, Geneva, Switzerland.
002919248 700__ $$aSiral, Ismet$$uCERN$$vCERN, Geneva, Switzerland.
002919248 700__ $$aSolans, Carlos$$uCERN$$vCERN, Geneva, Switzerland.
002919248 700__ $$aWei, Yingjie$$uOxford U.$$vDepartment of Physics, Oxford University, Oxford, UK.
002919248 8564_ $$82694785$$s75279$$uhttp://cds.cern.ch/record/2919248/files/fig_03.png$$y00013 Comparison between the measured and expected radiation length map. The largest differences are seen at the connectors and the SMD components, related to both their material budget as well as their placement on the PCB.
002919248 8564_ $$82694786$$s62789$$uhttp://cds.cern.ch/record/2919248/files/fig_02.png$$y00012 : Estimate : Measured and estimated fractional radiation length $x/X_0$ for an ITkPix v1.1 pixel quad module, populated with a $150\,\mu\text{m}$ planar sensor and a quad flex v2.4. For the measured map, the inverse Highland formula has been used to convert the measured $\theta$ RMS values into $x/X_0$ values. The areas of largest radiation length correspond to the power and data connectors, the high voltage (HV) decoupling capacitor and the SMD components.
002919248 8564_ $$82694787$$s80140$$uhttp://cds.cern.ch/record/2919248/files/fig_01.png$$y00011 : Measurement
002919248 8564_ $$82694788$$s27793$$uhttp://cds.cern.ch/record/2919248/files/telescope.png$$y00002 MONSTAR telescope configuration and trigger scheme. Multiple scattering within the DUT produces track kinks, which are analysed to derive the radiation length of the DUT.
002919248 8564_ $$82694789$$s46763$$uhttp://cds.cern.ch/record/2919248/files/fig_05.png$$y00007 : Double sided crystal ball (DSCB) fit
002919248 8564_ $$82694790$$s69680$$uhttp://cds.cern.ch/record/2919248/files/fig_04.png$$y00009 Measured radiation length $x/X_0$ for an ITkPix v1.1 pixel quad modue. The radiation length is extracted from the multiple scattering angle of $1.2\,\text{GeV}$ positrons in the quad module using the inverse Highland formula. The radiation length map is shown before subtraction of the air and the module holder contributions.
002919248 8564_ $$82694791$$s237828$$uhttp://cds.cern.ch/record/2919248/files/module_holder.png$$y00004 : Photograph of installation in telescope.
002919248 8564_ $$82694792$$s193795$$uhttp://cds.cern.ch/record/2919248/files/monstar.png$$y00003 MONSTAR telescope setup during the CERN PS testbeam measurement.
002919248 8564_ $$82694793$$s43404$$uhttp://cds.cern.ch/record/2919248/files/dscb_response.png$$y00010 Simulation of the measured scatter angle RMS for various assumed true $x/X_0$ values of a homogeneous silicon DUT. The bands obtained from simulation are shown before (blue) and after the air + telescope subtraction (orange). The latter is compared to the to expectation from Highland and Fr\"uhwirth-Regler (dashed lines). Both unsubtracted and subtracted simulations are compared to the reference measurement with a $50\,\mu$m thick MALTA plane as the DUT. On the left plot of the figure, the Highland and Fr\"uhwirth-Regler lines overlap. Their difference is only visible in the ratio plot on the right of the figure.
002919248 8564_ $$82694794$$s31282$$uhttp://cds.cern.ch/record/2919248/files/module_holder_2.png$$y00005 : Design render. : Custom mounting plate used to provide mechanics and cooling for the ITkPix module, annotated with the relevant components. The location of the Peltier elements between the holder and heatsink is denoted by the blue shaded regions. The window size beneath the module used during the measurement was $35 \times 25\,\text{mm}^2$.
002919248 8564_ $$82694795$$s146139$$uhttp://cds.cern.ch/record/2919248/files/module.png$$y00000 Annotated render of an ITkPix quad module, with a cutaway revealing the main layers. The high voltage (HV) capacitor and the data and power connectors have been highlighted as these are substantial contributions to the material budget of the module.
002919248 8564_ $$82694796$$s9974897$$uhttp://cds.cern.ch/record/2919248/files/2412.04686.pdf$$yFulltext
002919248 8564_ $$82694797$$s136088$$uhttp://cds.cern.ch/record/2919248/files/scattering_behaviour.png$$y00001 Relationship between beam energy and multiple scattering distribution width predicted for electrons/positrons for varying spacing distances between a subject with $x/X_0 = 0.8\%$ and the furthest downstream plane. The RMS of the scatter distribution $\sigma$, which equals $\theta^{\text{RMS}}$ in Equation \ref{eq:highland}, is shown in units of $\mu \text{m}$ (left) and the FWHM of the distribution is shown in units of Malta pixel pitches (right). The red and blue color backgrounds indicate the energy range where the PS T9 beam is dominated by positrons and pions, respectively. The intensity of the color is indicative for the expected rate. The horizontal blue line marks the upper limit where the scatter FWHM equals the sensor width, the horizontal red line marks the lower limit where the scatter FWHM equals the pixel pitch. The area highlighted in yellow indicates the expected telescope geometry and beam energy constraints for such measurements. The measurement presented in this paper is indicated as a violet point.
002919248 8564_ $$82694798$$s28712$$uhttp://cds.cern.ch/record/2919248/files/global_angle_divide.png$$y00006 Transformation of the global angle $\theta_g$ to a pseudo-projected angle.
002919248 8564_ $$82694799$$s39779$$uhttp://cds.cern.ch/record/2919248/files/c2_violins.png$$y00014 Violin plots comparing the estimated $x/X_0$ distribution of the ITk pixel module with three different extraction methods, based on the Highland formula, the Fr\"uhwirth-Regler formula and a GEANT4 based mapping of the measured $\theta$ to the underlying $x/X_0$ values.
002919248 8564_ $$82694800$$s47354$$uhttp://cds.cern.ch/record/2919248/files/fig_06.png$$y00008 : Single sided crystal ball (SSCB) fit : Example $\theta_x$ and $\theta_g$ distributions and fit functions for one bin of one position of the DUT. The uncertainties on the quoted $x/X_0$ values include only statistical uncertainties.
002919248 960__ $$a11
002919248 980__ $$aPREPRINT