Project Specification Project Name: AGATA Project Identifier: 186 Version: Draft 0.3

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CCLRC Engineering Department
-

Project Engineering Division

Project: 186. AGATA Version draft

last modified 10/2/5


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Project Specification


Project Name: AGATA


Project Identifier: 186


Version: Draft 0.3



Approval:




name

signature

date



Project Manager PED

K. Fayz


9/2/2005





Distribution for all updates:


Project Manager PED:




K. Fayz

Customer:






J. S
impson

Group Leader responsible for the project:

N. Bliss

Project Managers of related projects:



CCLRC Engineering Department
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Project Engineering Division

Project: 186. AGATA Version draft

last modified 10/2/5


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1.0 Scope



The
“Advanced GAmma Tracking Array”

(AGATA) will be a 4



-
ray spectrometer built entirely
from Germanium detectors. It is a large European col
laboration involving many laboratories and
institutions. AGATA will be orders of magnitude more powerful than all current and near
-
future
gamma
-
ray spectrometers. It will be an instrument of major importance for nuclear structure studies at

the very limits

of nuclear stability. AGATA will enable the pursuit of a very rich science program
using both radioactive and stable ion beams.

The AGATA project is based on the technological achievements obtained in recent years by the
European gamma
-
ray spectroscopy c
ommunity and especially within the
European TMR Network
Project
Development of

-
Ray Tracking Detectors for 4



-
Ray Arrays,
in which a proof of concept
for the novel technique of

-
ray tracking has been achieved.


The first phase of the AGATA project is
a research and development phase. In this 5 year phase a
sub
-
array of detector modules will be built.


1.1 The scope and objectives of mechanical design.

The first phase of the project involves the design of a sub array of detector units, called the
demon
strator. The demonstrator will comprise up to 15 (possibly 18) Ge crystals, which are grouped
into three in separate cryostats, see below. This demonstrator will eventually form part of the full
4


ball of Ge detectors. Therefore, the first phase of the me
chanical design is to construct the full 4


array of these identical units. Once this conceptual design for the full ball is proved the detailed
design of the demonstrator will take place.

The mechanical design includes:

1
-

Conceptual mechanical engineeri
ng design of the detector modules, the ball and holding structure
of the full 4


array.

2
-

Finite element analysis for the full
4


array
.

3
-
1
-

Mechanical engineering design of the mechanical holding structure for the demonstrator.

4
-
Production of detailed
and assembly drawings for the demonstrator.

5
-
Writing specifications for procurement of major components


2.0 Documents


The mechanical aspects of AGATA are part of the larger collaboration involving all parts of the
project. A central folder is available
to contain all related documents of which access is given to
interested parties/ collaborators. These documents will also be available on the web page
http://npg.dl.ac.uk/documentation
/AGATA/specifications/
.


3.0 Technical Aspects


3.1 The detectors and associated structure.

The chosen geometry for the AGATA spectrometer is based on tiling the sphere with 180 hexagons
and 12 pentagons. This is shown schematically in Figure 1. In this
geometry the 180 hexagons can be
grouped into 60 identical triple modules or clusters. It was decided early on in the project that the
fraction of efficiency brought by using the pentagons was not worth the cost of developing and
handling this crystal shap
e. The resulting gaps will be useful for supporting the array.

CCLRC Engineering Department
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Project: 186. AGATA Version draft

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The table below summarises some of the characteristics of the 180 detector geometry.


Number of crystals

180

Solid Angle (%)

80

Inner free space (cm)

21*

Number of clusters / types

60 /
1

Rings of clusters

5
-
10
-
15
-
15
-
10
-
5

Angular coverage of rings

very regular


The geometry of the germanium crystals and capsules has been defined by an Italian collaboration
(Bazzacco, Fanin, Farnea et al.,). There are three types of capsule of slightly
differing shape,
indicated as red, blue and green in Figure 1. This geometry was supplied to the company Canberra
Eurisys (CE) in 2004. CE produced drawing of the detector capsules from this geometry and this
geometry has been checked and agreed by the col
laboration (Daresbury, Padova, Legnaro, Cologne).
The 180 crystals are grouped (red, blue, green) into three's to form a single detector (see figures 1 and
2).


The Ge detector cryostat will compromise of four parts; the three encapsulated germanium crysta
ls,
the electronics (pre
-
amplifiers, etc), the mechanical cryostat and the carrying structure (see figure 2).



Figure 1. The 180 detector geometry of AGATA.

CCLRC Engineering Department
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Project: 186. AGATA Version draft

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Figure 2: Detector cryostat schematic. Courtesy of CCT.


The four parts are designed in consultation/ collaboration with the relevant suppl
iers and institutes.


The specification for the triple cryostat can be found at

http://npg.dl.ac.uk/documentation/AGATA/specifications/Triple
-
asymmetric
-
cryostat.doc



CCLRC Engineering Department
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The first stage of the design involves building the full 4


ball of detectors using the agreed capsule
design and the proposed triple cryostat. The detailed design of the triple cryostat is a collaboration
between the collaboration and a c
ommercial supplier (CTT).


From the information supplied the full detector module has been built into the CAD system at
Daresbury.
Figure 3 shows a drawing of a triple detector module. This arrangement has been
constructed using information from both CE a
nd the cryostat company CCT.



Figure 3. Detector crystals


The angle between each crystal is 9.4242° with a radius of 233.7mm from the target centre.

This triple module requires mechanical support that allows the full ball to be assembled. A proposed
scheme involving a separate flange for each triple cryostat is shown in Figures 4 and 5. The angle
between each detector (figure 4) is set at 21.9679˚. The demonstrator, and indeed the full ball, will be
assembled by bolting the array flanges together to f
orm a mechanically sound structure.


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Figure 4. Detector unit (Cryostat, flange, dewar).




AGATA mechanical structure for part of the full ball





Assembly flange

Figure 5: Part of the full ball the assembly flange.

All components must not
protrude beyond this
perimeter

Array flange

Crystal canes

Dewar

Detector support
fla
nge

485.5 mm

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The structure

will need to be supported of a platform. It is assumed that the full ball will be required
to be split into two half spheres to allow access to the target centre and the beam line.

Ease and safe removal and installation of each detector is required. A de
tector manipulator will be
used for this process. It will permit ease of access to the various detectors at all radial positions.

3.2 Infrastructure and associated items.


The full array and the demonstrator have additional items that affect the mechanica
l design that have
to be taken into account. These include:



An automatic liquid nitrogen filling system needed to keep the Ge detectors cold.



Local electronics. Digitizers, high and low voltage, slow control.



Cables



Host laboratory constraints



Grounding



Mo
tion controls


The overall layout of the ball, detectors and associated infrastructure needs to be specified and
agreed. Part or the entire infrastructure (autofill, electronics controls etc.), may be located on the
support platform and the fixtures used f
or the infrastructure may also be used to support the ball.

The design of the target chamber, beamline and any tracking/ ancillary detectors also needs to be
specified.


3.3 Material requirements


All structural components will be manufactured from a mec
hanically viable structural material that
will be able to support the array. Investigation into conventional material (mild steel, Aluminium),
which have been used on previous Nuclear Physics projects, as well as non
-
conventional materials
(titanium alloys
... etc.) is to be carried out with emphases on cost and mechanical properties. The
array platform and support stand will be manufactured from mild or St
-
St steel.


Grounding requirements need to be specified since insulating material maybe required.


3.4

Vacuum requirements


AGATA will be operating under atmospheric conditions. Vacuum requirements for target chamber
are to be determined by the host laboratory(s). Full mechanical details of vacuum chambers and target
chambers need to be part of the overall

mechanical design drawing register.


3.5 Signal requirements


To be determined, cabling is required for all detectors plus any motion control equipment (motors.
etc.).


3.6 Access and assembly requirements


As described in section 3.1


3.7 Specification
of deliverables


a)

Manufacturing drawings

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Project: 186. AGATA Version draft

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The following drawings are required for the
4


array
:



overall general arrangement drawing



detailed drawings of main array



detailed drawings of support stand and associated components

The following drawings are requi
red for the
demonstrator
:



overall general arrangement drawing



detailed drawings of main array



detailed drawings of support stand and associated components



b)

Project management documentation

The following documentation will be produced:



manufacturing budget

estimate



mechanical design and engineering manpower estimates



overall project schedule for design, manufacture and assembly


All manufacturing drawings and project management documentation is listed on the Master
Documentation List, and reviewed at each
design review.


3.8 Manufacturing


Industry and the collaborating institutions will carry out all manufacturing. The UK design team can
recommend or place orders with suitable suppliers and monitor the progress of these suppliers if
required.


3.9 Testin
g and product control


Preassembly and test will be organised and carried out at Daresbury (if appropriate) and the
collaborating institutions.


3.10 Shipping and installation


Persons responsible for organising shipped to be decided.


3.11 Maintenance and

further orders


Persons responsible for maintenance will be assigned by the host laboratory


4.0 Project Management


4.1 Personnel


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4.2 Deliverables


As 3.7


4.3 Project plan


Refer to project schedule version 1.0 for design, procurement and assembly (18
6.51xxxdraft).


4.4 Design Reviews


Through the course of the feasibility study, the project specification is developed.

At the preliminary design review (PDR) the draft specification is agreed.

At the interim design review (IDR) the specification should

be updated to reflect any significant
changes in technical requirements and deliverables.

At the final design review (FDR) the specification may be further updated. It is essential that the FDR
is complete prior to any orders being placed. As the specific
ation is updated, copies are circulated to
all personnel.

After project installation and commissioning, a concluding review (CR) is held.

Minimum personnel for PDR, IDR, FDR and CR are J Simpson & K. Fayz.


Throughout the entire project, project monitor fo
rms (PMF’s) are completed on a monthly basis.
These are circulated to the customer.


4.5 Training


No additional training is required.


4.6 Test Equipment


All equipment used for testing will be supplied by DL or outside industry. All cleaning and vacuum
t
esting will be in accordance with the host lab.


4.7 Costs and finance


Refer to version 1.0 of the mechanical cost for manufacture (186.xxxx draft), and version x.x of the
manpower estimate for design (to be determined).


a)

Sources of funding

Project Engin
eering Division, Engineering Department CLRC is providing a design service to the
Surface and Nuclear Division, who in turn obtain funding from EPSRC.


PERSONNEL

DEPARTMENT

TEL. NO

FAX. NO

e
-
mail Address

Project Leader





K. Fayz

Engineering

01925 603577

01925 603416

k.fayz@dl.ac.uk






Project Team





R. Griffiths

Engineering

01925 603521

01925 603416

r.griffiths@dl.ac.uk

D. Seddon

Liverpool
Uni
versity

0151 794 3406


Das@ns.ph.liv.ac.uk

Collaborators










Customer





J Simpson

Nuclear Physics

01925 603431

01925 603173

j.simpson@dl.ac.uk


CCLRC Engineering Department
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Project: 186. AGATA Version draft

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b)

Cost centres

Staff costs


To be determined

Capital expenditure


To be determined


c)

Method of payment

T
he Nuclear Physics Group division will approve all orders that are placed by CCLRC.


d)

Method of monitoring costs

Project costs will be monitored and any significant deviation from the budget estimate will be
highlighted in the project monitor forms (PMF’s).


4.8 IPR and confidentiality


Subject to the pre
-
existing rights of the Customer and of any third party, ownership of any
information, drawings and designs generated, owned or used by the Council in connection with the
performance of the Work shall reside

with the Council.


4.9 Safety & Environmental impact


In this application AGATA will operate using radioactive ion beam. Therefore it is essential that all
local and international rules and regulations are followed for the handling and disposal of radioac
tive
substances.