GLAST Italia 1 Milano - 16/03/01 GLAST: Gamma Ray Large Area Telescope GLAST-Italia: Partecipation to the LAT and construction commitments R.Bellazzini.

1 Milano - 16/03/01GLASTGLAST

Italia

GLAST:Gamma Ray Large Area Telescope

GLAST-Italia:Partecipation to the LAT

and construction commitments

R.BellazziniItalian Project Manager


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Pair-Conversion Telescope

GLAST Concept• Low profile for wide f.o.v.• Segmented anti-shield to

minimize self-veto at high E.• Finely segment calorimeter for

enhanced background rejection and shower leakage correction.

• High-efficiency, precise track detectors located close to the conversions foils to minimize multiple-scattering errors.

• Modular, redundant design.• No consumables.• Low power consumption (580 W)

Calorimeter (energy measurement)

Particle tracking detectors

Conversion foils

Charged particle anticoincidence shield

e+ e-

Photons materialize into matter-antimatter pairs:

E -> me+c2 + me-c2


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The Large Area Telescope (LAT)

DAQ Electronics

Grid

Tracker

Calorimeter

ACD Thermal Blanket

•Array of 16 identical “Tower” Modules, each with a tracker (Si strips) and a calorimeter (CsI with PIN diode readout) and DAQ module.

•Surrounded by finely segmented ACD (plastic scintillator with PMT readout).

•Aluminum strong-back “Grid,” with heat pipes for transport of heat to the instrument sides.


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The LAT Hardware


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GLAST Tracker Design Overview

• 16 “tower” modules, each with 37cm 37cm of active cross section

• 83m2 of Si in all, like ATLAS • 11500 SSD, ~ 1M channels• 18 x,y planes per tower

– 19 “tray” structures•12 with 3% Pb or W on bottom (“Front”)•4 with 18% Pb or W on bottom (“Back”)•2 with no converter foils

– Every other tray is rotated by 90°, so each Pb foil is followed immediately by an x,y plane of detectors

•2mm gap between x and y oriented detectors

• Trays stack and align at their corners• The bottom tray has a flange to mount on the

grid.• Electronics on sides of trays:

– Minimize gap between towers– 9 readout modules on each of 4 sides

Electronics flex cables

Carbon thermal

panel

One Tracker Tower Module


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Tray assembling

Carbon-carbon closeout

• Trays are C-composite panels (Al hexcel core)

• Carbon-fiber walls provide stiffness and the thermal pathway

from electronics to the grid.


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Prototyping of the GLAST SSD

Preserie HPK detectoron 6’’ wafer

Gained experience with a large number of SSD (~5% of GLAST needs)

Additional Prototypes:Micron (UK), STM (Italy), CSEM (Switzerland)


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Project schedule

2000 2001 2002 2003 2004 2005 2010

Formulation Implementation

SRR NAR M-PDR M-CDRI-PDR I-CDR Inst. Delivery Launch

Build & TestEngineering Models

Build & TestFlight Units

Inst.I&T

ScheduleReserve

Inst.-S/CI&T

Ops.

Calendar Years

SSD Procurement SSD Procurement

Ladder Production Ladder Production

Tray AssemblyTray Assembly


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INFN Collaboration

Sezioni INFN

BariPerugi

aPisa

Roma 2TriesteUdine

Collaborations

Dipartimento di Ingegneria Aerospaziale (Univ. Pisa)

Dipartimento di Ingegneria dei Materiali (Univ. Perugia)

30 FTE physicists


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GLAST-RDLa Commissione ha gia’ espresso il suo grande interesse per l’ esperimento nelladiscussione avvenuta ad Ottobre. Si prend e atto che la collaborazione si e’ulteriormente rafforzata con l’ingresso del gruppo di Bari associato a PaoloSpinelli. Viene presentata una relazione di aggiornamento da parte di GuidoBarbiellini e Ronaldo Bellazzini; viene ascoltata la relazione dei referees (MarcoGrassi ed An tonio Surdo). Viene esaminata la bozza di Memorandum ofAgreement e vengono discusse e suggerite alcune ipotesi migliorative.La Commissione e’ orientata ad app rovare il progetto. Nella ipotesi di unfinanziamento dell’esperimento egualmente diviso fra INFN ed ASI, come e’apparso probabile nel recente incontro della Commissione mista INFN/ASI, siritiene congrua una spesa per la realizzazione dell’apparato sperimentale cherisulti globalmente inferiore ad un totale di 20 GL, somma che la CommissioneNazionale II ritiene non debba in nessun caso essere superata.Viene comunicato che un incontro e’ previsto il 24 Gennaio fra il P rof.Barbiellini e la Commissione mista INFN/ASI. La Commissione Nazionale IIrichiede di precisare ulteriormente le responsabilita’ costruttive assunte in basealla nuova configurazione della collaborazione. Richiede un p iano pluriennalecomplessivo di spesa, in particolare per tutti gli aspetti non ancora adeguatamentedettagliati, come le missioni nazionali ed estere, i consumi, etc. Ad integrazionedel parziale finanziamento assegnato a Ottobre, viene attribuita una sommaaggiuntiva di 655 ML, come dettagliato nella tabella allegata. La collaborazionerichiede ulteriori finanziamenti per il 2001 , in particolare per attrezzature(importo di circa 700 ML), che la Commissione giudica accettabili, ma che none’ attualmente in grado di soddisfare. La questione verra’ eventualmente ripresain corso d’anno.

Estratto dal verbale della riunione dellaCommissione Scientifica II

Roma 15-16 gennaio 2001

Status of INFN approval process

INFN is willing to approve

Construction money ceiling (INFN+ASI) of

20 GL˜ 9.5 M$


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…...

…...

GLAST: MoA

and ASIand ASI


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Construction commitment

and ASI


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and ASI



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Mechanics: on-going activities

Ladders:• Design and production of jiigs and tools for ladders assembly• Definition of alignment and glueing procedure of ladders on trays• Ladders prototyping in collaboration with industries (G&A, MIPOT, LABEN)Trays:• Super-GLAST payload definition and prototyping (PLYFORM)• Definition of trays acceptance mechanical tests • Construction of 4 trays fully equipped with final sensors and electronics Towers: • Construction of a tower Engineering Model (19 trays) for qualification of procedures and industrial partners


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Sensors: on-going activities

Qualification of sensor Suppliers:

• Complete set of measurements on pre-serie prototypes from

various suppliers ( HPK-Japan, Micron-UK, ST-Italy ):

inter-strip capacitance, bulk capacitance, depletion voltage, dark

current, decoupling capacitance and resistance, ...

Definition of automatic test procedures for mass production


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Comparison between HPK and GLAST resultsMeasurements at Hiroshima U. (20), INFN-Pisa (10), SLAC (5)

Tests on preserie of final HPK SSD


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Tests on preserie of final HPK SSD

Mechanics and dimension measurements

ThicknessStrip size = 64 ± 1 mPitch = 228.01 ± 0.01 mActive width = 87557 ± 5 m

Average tilt

Planarity

0.5

0.4

0.3

0.2

0.1

0.0

Detector ID

HPK preseries


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Software: on-going activities

Simulation - development in G4 of the GLAST-LAT - XML description of LAT geometry - digitization (charge sharing, FE simulation, TOT)- MC validation

Track reconstruction- study of TOT to improve vertexing- angular accuracy study - energy measurement from angular dispersion- development of a reduced version of reconstruction package

lab-tests of stack of trays or a tower with cosmic rays

Interactive event display (evaluating WIRED2)


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XML C++ generic model

We have done the C++ hierarchy of classes for accessing the XML geometry description of GLAST


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Gamma Ray Telescope G4 example

Official advanced example in release 3.0 of G4...


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Conclusions

• Activity of GLAST-Italy started full steam on both hardware and software

• The Italian Collaboration is providing critical contributions to the LAT design and to the preparation for construction

• Strong need of fast signature of MoA between STANFORD/SLAC and ASI/INFN

•Strong need of formal approval from INFN and ASI of the spending profile to start soon tenders for SSD procurement on tracker construction

GLAST Italia 1 Milano - 16/03/01 GLAST: Gamma Ray Large Area Telescope GLAST-Italia: Partecipation to the LAT and construction commitments R.Bellazzini.

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