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

2. Pair-Conversion Telescope
Photons materialize into matter-antimatter pairs:
E -> me+c2 + me-c2  e+ e-
Calorimeter
(energy measurement)
Particle tracking detectors
Conversion foils
Charged particle anticoincidence shield
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)
Milano - 16/03/01

3. 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.
Milano - 16/03/01

4. The LAT Hardware
Milano - 16/03/01

5. 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
Milano - 16/03/01

6. 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.
Milano - 16/03/01

7. Prototyping of the GLAST SSD
Preserie HPK detector
on 6’’ wafer
Gained experience with a large number of SSD (~5% of GLAST needs)
Additional Prototypes:
Micron (UK), STM (Italy), CSEM (Switzerland)
Milano - 16/03/01

8. Project schedule Calendar Years Formulation Implementation SRR NAR
2000
2001
2002
2003
2004
2005
2010
Formulation
Implementation
SRR
NAR
M-PDR
M-CDR
I-PDR
I-CDR
Inst. Delivery
Launch
Build & Test
Engineering Models
Flight Units
Inst.
I&T
Schedule
Reserve
Inst.-S/C
Ops.
Calendar Years
SSD Procurement
Ladder Production
Tray Assembly
Milano - 16/03/01

9. INFN Collaboration Sezioni INFN Bari Perugia Pisa Roma 2 Trieste Udine
30 FTE physicists
Collaborations
Dipartimento di Ingegneria Aerospaziale (Univ. Pisa)
Dipartimento di Ingegneria dei Materiali (Univ. Perugia)
Milano - 16/03/01

10. Construction money ceiling (INFN+ASI) of 20 GL
Status of INFN approval process
Construction money ceiling (INFN+ASI) of 20 GL
˜ 9.5 M$
INFN is willing to approve
Milano - 16/03/01

11. GLAST: MoA
…...
and ASI
and ASI
…...
Milano - 16/03/01

12. Construction commitment
and ASI
Milano - 16/03/01

13. Construction commitment
and ASI
Milano - 16/03/01

14. Construction commitment
Milano - 16/03/01

15. Construction commitment
Milano - 16/03/01

16. Construction commitment
Milano - 16/03/01

17. 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
Milano - 16/03/01

18. 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
Milano - 16/03/01

19. Tests on preserie of final HPK SSD
Comparison between HPK and GLAST results
Measurements at Hiroshima U. (20), INFN-Pisa (10), SLAC (5)
Milano - 16/03/01

20. Tests on preserie of final HPK SSD
Mechanics and dimension measurements
Average tilt
Planarity
Thickness
Strip size = 64 ± 1 mm
Pitch = ± 0.01 mm
Active width = ± 5 mm
Milano - 16/03/01

21. 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)
Milano - 16/03/01

22. XML C++ generic model
We have done the C++ hierarchy of classes for accessing the XML geometry description of GLAST
Milano - 16/03/01

23. Gamma Ray Telescope G4 example
Official advanced example in release 3.0 of G4...
Milano - 16/03/01

24. 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
Milano - 16/03/01