Detector Alignment Activities

Tapio Lampén 22nd May 2006, page 1

Detector Alignment Activities

Evaluation of HIP CMS Software and Physics Project

22nd May 2006

T. Lampén

Tapio Lampén 22nd May 2006, page 2CMS Pixel

Overview

Alignment with tracks with HIP algorithm

Helsinki Silicon Beam Telescope

Cosmic Rack setup

CMS Pixel

Misalignment simulation of CMS

participated to sw development: tools and ready-made misalignment scenarios

Quality control of Tracker Outer Barrel (TOB)rod manufacturing

hands-on insight to misalignments

Cosmic Rack

SiBT

Tapio Lampén 22nd May 2006, page 3

Timeline of Alignment Activities

200620052004200320022001 2007

Px alignment, CMS reconstruction sw

CMS misalignments

2000

2008 2009

supportingactivities

22.5.2006

SiBT Alignment

Rod measurements

Px alignment, stand-alone

Cosmic Rack Alignment

Tapio Lampén 22nd May 2006, page 4

Alignment with tracks – background

begun 1998: Silicon Beam Telescope (SiBT)2-parameter alignment of individual modules

Alignment algorithm developed further (and published)all 3+3 parameters for individual modulesnamed as HIP algorithm (Hits and Impact Points)

Applied toSiBT, several timesCMS Pixel 2002, standalone swCMS Pixel alignment, official sw (on-going)Alignment of Cosmic Racks (on-going)

CMS TOB CRack (CERN)FinnCRack (Helsinki)

Cosmic Rack

Tapio Lampén 22nd May 2006, page 5

Alignment with Tracks - status

A high-priority issue for start-up & long-term operation!

3 Alignment algorithms studied within CMS (see also Physics TDR 1):HIP algorithm, Helsinki (CMS-Note 2006/018)

Millepede, Hamburg (CMS Note 2006/011)

Kalman filter, Vienna (CMS Note 2006/022)

HIP algorithm most robust and computationally light,a promising candidate for Pixel alignment,(no optical alignment system for Pixel)

HIP algorithm currently most developed algorithm

3 CMS Notes in 2005/2006, Physics TDR 1 contribution, active reporting in conferences

Tapio Lampén 22nd May 2006, page 6

Alignment with Tracks – future plans

Currently studying Pixel alignment with HIP algorithm withminimum bias eventscosmics, beam halo eventsJ/Psi eventsmuons from Z,W

Production of min. bias events with computer cluster in Helsinki

Goal in near future: refine alignment strategy for pixel

Goal in longer term: active part in track-based alignment of CMS Tracker before and during operation

Co-operation with HIP Tracker project: FinnCRack

Manpower: VK + TL, summer students

Tapio Lampén 22nd May 2006, page 7

ideal strip detector used100k m.b.

eventsindividual pixel

modules aligned with HIP algorithm20 iterationsconverges to

level of few tens of umencouraging

results

Alignment with tracks – example of HIP algorithm with min. bias

events

u v w

zyx

Misalignments in local coordinates of all individual pixel moduls

In global coordinates

Loca

iteration

mis

alig

nmen

tm

isal

ignm

ent

iteration iteration

Tapio Lampén 22nd May 2006, page 8

Example of Cosmic Rack alignment(Physics TDR)

Track Chi^2 convergence

A particular moduletranslation rotation

testbeam data, alignment of 2 parameters

Tapio Lampén 22nd May 2006, page 9

Simulation of Misalignments

To study alignment algorithm, initial misalignments need to be simulated

Same tools can be used to introduce estimated misalignments

We have in 2004-2005implemented tools for Pixel misalignment in ORCA softwareparticipated actively in development of the Misalignment Scenarios of the CMS (CMS Note 2006/008)

First data scenario (after 100 pb-1)Long term scenario (after 1 fb-1)

A natural introduction to alignment studies!

Tapio Lampén 22nd May 2006, page 10

TOB Rod Quality Control

All 750 Tracker Outer Barrel support rods manufactured and measured in Helsinki

Measurements serve as quality control,but also provide initial alignment parameters

This work also supports well alignment studies and gives realistic insight to actual misalignments!

Measurement JigMeasurement Probe

Translation of a module Rotation of a module

Limits for good / acceptable values, limits for rejection out of plot range

RMS 40 um

RMS 0.2 mrad

Tapio Lampén 22nd May 2006, page 11

Summary and Plans

Main activity: software alignment by tracks with HIP algorithm, high-priority issue for CMS

HIP algorithm most developed of the 3 algorithms within CMS,reported in Physics TDR 1

Goals: 2006: optimize alignment strategy for pixel with HIP algorithm2007: participate actively to initial alignment of CMS Tracker2008: long-term alignment of CMS Tracker

Work for one grad. student, tasks for summer students

Proceeding with good momentum: 3 CMS Notes in January 2006, conference talks (CHEP06), etc.