Selection of the silicon sensor thickness for the Phase-2 upgrade of the CMS Outer Tracker

During the operation of the CMS experiment at the High-Luminosity LHC the silicon sensors of the Phase-2 Outer Tracker will be exposed to radiation levels that could potentially deteriorate their performance. Previous studies had determined that planar float zone silicon with n-doped strips on a p-doped substrate was preferred over p-doped strips on an n-doped substrate. The last step in evaluating the optimal design for the mass production of about 200 m$^{2}$ of silicon sensors was to compare sensors of baseline thickness (about 300 μm) to thinned sensors (about 240 μm), which promised several benefits at high radiation levels because of the higher electric fields at the same bias voltage. This study provides a direct comparison of these two thicknesses in terms of sensor characteristics as well as charge collection and hit efficiency for fluences up to 1.5 × 10$^{15}$ n$_{eq}$/cm$^{2}$. The measurement results demonstrate that sensors with about 300 μm thickness will ensure excellent tracking performance even at the highest considered fluence levels expected for the Phase-2 Outer Tracker

Beam test performance of a prototype module with Short Strip ASICs for the CMS HL-LHC tracker upgrade

The Short Strip ASIC (SSA) is one of the four front-end chips designed for the upgrade of the CMS Outer Tracker for the High Luminosity LHC. Together with the Macro-Pixel ASIC (MPA) it will instrument modules containing a strip and a macro-pixel sensor stacked on top of each other. The SSA provides both full readout of the strip hit information when triggered, and, together with the MPA, correlated clusters called stubs from the two sensors for use by the CMS Level-1 (L1) trigger system. Results from the first prototype module consisting of a sensor and two SSA chips are presented. The prototype module has been characterized at the Fermilab Test Beam Facility using a 120 GeV proton beam

Comparative evaluation of analogue front-end designs for the CMS Inner Tracker at the High Luminosity LHC

The CMS Inner Tracker, made of silicon pixel modules, will be entirely replaced prior to the start of the High Luminosity LHC period. One of the crucial components of the new Inner Tracker system is the readout chip, being developed by the RD53 Collaboration, and in particular its analogue front-end, which receives the signal from the sensor and digitizes it. Three different analogue front-ends (Synchronous, Linear, and Differential) were designed and implemented in the RD53A demonstrator chip. A dedicated evaluation program was carried out to select the most suitable design to build a radiation tolerant pixel detector able to sustain high particle rates with high efficiency and a small fraction of spurious pixel hits. The test results showed that all three analogue front-ends presented strong points, but also limitations. The Differential front-end demonstrated very low noise, but the threshold tuning became problematic after irradiation. Moreover, a saturation in the preamplifier feedback loop affected the return of the signal to baseline and thus increased the dead time. The Synchronous front-end showed very good timing performance, but also higher noise. For the Linear front-end all of the parameters were within specification, although this design had the largest time walk. This limitation was addressed and mitigated in an improved design. The analysis of the advantages and disadvantages of the three front-ends in the context of the CMS Inner Tracker operation requirements led to the selection of the improved design Linear front-end for integration in the final CMS readout chip

Test beam performance of a CBC3-based mini-module for the Phase-2 CMS Outer Tracker before and after neutron irradiation

The Large Hadron Collider (LHC) at CERN will undergo major upgrades to increase the instantaneous luminosity up to 5–7.5×10$^{34}$ cm$^{-2}$s$^{-1}$. This High Luminosity upgrade of the LHC (HL-LHC) will deliver a total of 3000–4000 fb-1 of proton-proton collisions at a center-of-mass energy of 13–14 TeV. To cope with these challenging environmental conditions, the strip tracker of the CMS experiment will be upgraded using modules with two closely-spaced silicon sensors to provide information to include tracking in the Level-1 trigger selection. This paper describes the performance, in a test beam experiment, of the first prototype module based on the final version of the CMS Binary Chip front-end ASIC before and after the module was irradiated with neutrons. Results demonstrate that the prototype module satisfies the requirements, providing efficient tracking information, after being irradiated with a total fluence comparable to the one expected through the lifetime of the experiment

Pilot Phase of the Randomized PlanB Trial: Prospective Comparison of Molecular Classification, Oncotype DX (R) and Clinical-Pathological Characteristics in Hormone-Receptor (HR) Positive Primary Breast Cancer

Abstract Background: Despite progress in adjuvant breast cancer (BC) treatment, overtreatment due to decisions based on conventional prognostic factors (lymph nodes (LN), grade, tumor size) alone remains an important clinical problem. Recurrence Score®, RS is validated using pre-specified analyses, genes, cutt-offs in several randomized patient collectives as a potent prognostic and predictive marker in HR positive BC. Here, we present the first WSG-Plan B trial preplanned correlation analysis of central grade, nodal status, RS, and luminal A/B subtypes. Material and Methods: The West German Study Group (WSG) Plan B trial (planned n=2,448) is a randomized Phase-III-trial evaluating anthracyline-free adjuvant chemotherapy (Cht) (6x TC) vs. standard 4xEC-4xDOC in high-risk N0 and N+ HER2-negative BC. In HR+ BC with 0-3 LN, RS is the decision criterion for (&amp;gt;11) or against (≥11) Cht randomization. Tumor blocks are prospectively evaluated by a central pathologist for grade, histology and Ki-67. In HR+ disease, molecular subtypes (luminal A vs. B) are grouped using a Ki-67 cut-off of 13.25% (Cheang et al, JNCI 2009) and 20% (Penault-Llorca et al JCO 2009). Exploratory analysis with Elston-Ellis central grade and Ki-67 based (mitosis measured by Ki-67) grade will be performed. Results: As of June 2010, 1375 patients in 96 centers have been registered and 1067 randomized into Plan B. In 298 patients, RS results and clinical-pathological characteristics were available. In 266 patients complete information on all factors was available (132 N0, 134 N+). RS groups using the pre-specified trial cut-offs of 0-11, 12-25 and &amp;lt;25 were 21%, 59%, and 20%, respectively, with a median of 18. RS groups using the standard cutt-offs (&amp;lt;18/18-30/&amp;gt;30) were 48%, 38%, 14%. Central grade 1, 2, or 3 was observed in 4%, 50%, and 46% of cases. We observed a modest (Spearman) correlation between central grade and RS (e.g 83.8% of G3 tumors with RS &amp;gt;25, rs=0.331, P&amp;lt;0.001), Ki-67 based grade (rs=0.34, P&amp;lt;0.001), and Ki-67 as continuous variable (median 20), (rs=0.438, P&amp;lt;0.001). No significant correlation was observed between nodal groups (0 vs. 1-3 vs. 4+) and RS groups (e.g. RS≥11 in N0/1-3/4+: 17.8%/22.6%/25.0%; p=0.253) Modest correlations were found for luminal A/B subtypes by both Ki-67 cut-off's (13.25%; 20%) and RS groups using our conservative trial cut-off (12/12-25/&amp;gt;25), and guideline-recommended &amp;lt;18/18-30/&amp;gt;30 (see table 1).Discussion: For the first time, we demonstrate a modest but significant correlation between centrally assed tumor grade, molecular classes by IHC Ki-67 cutt offs, and RS, particularly in the high RS group. However, our data also indicate that there is substantial discordance between the methods and thus an urgent need for optimzing risk-stratification classifiers. Table 1. Association of RS and molecular subtypes Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-10-12.</jats:p