AIDA: Advanced Implantation Detector Array
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Implantation-Decay Correlation
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Very high energy (~50-200MeV/u or ~5-20GeV A=100 ions, 0.2-0.9nC),
very exotic (i.e. radioactive) heavy-ions are implanted into a stack
of double-sided silicon strip detectors (DSSSDs). These nuclei subsequently
undergo radioactive decay emitting beta particles, protons, alphas, neutrons
and gamma-rays. The charged particles are detected by the DSSSDs.
Beta particles characterised by continuum energy spectra to low energies.
Other charged particles are characterised by discrete peaks. The neutrons
and gamma-rays are detected by neutron and gamma detector arrays close
packed around DSSSDs. 

The DSSSD strips identify where [x,y] and when [t_0] the nuclei were
implanted. Subsequent radioactive decay(s) at the same position [x,y]
at times [t_1 (, t_2 ... )] can be correlated with the implant.
Observation of a number of such correlations enables us to determine
the energy distribution of the radioactive decay and its half-life
(decay time).

If the implantation events are distributed across a highly segmented
DSSSD the average time between implants at each position [x,y] is
greater than the average decay time and random correlations (two, or
more implants at the same position followed by radioactive decays -
which decay correlates with which implant ...?) are minimised. For a 
given decay time, higher segmentation means a higher total implantation
rate.

Practicalities
--------------

The energy deposited by the implant in the DSSSD ~GeV, and higher.
The energy of the subsequent decay events ~MeV.
Average time between implantation and decay ~us-s.

We cannot assume that it will be possible to pre-empt the arrival
of high energy implants by, for example, switching the preamps to
reset. The instrumentation must detect, respond and recover itself. 

DSSSD array area ~24cmx8cm. Each layer of DSSSD stack consists of
three 8cm x 8cm area, 1mm thick, DSSSDs with ~128x128 strips each.
Strips on one side of the DSSSD wafer are series connected.
The stack consists of ~10 such layers - 8 intermediate layers
to detect decays, one front dE (low gain) and one back Veto (low
gain) which correlate the arrival of ions with upstream detectors
and whether ions stop in the intermediate layers respectively.

Another configuration will have an array area of ~8cmx8cm (common
DSSSD wafer design).

The array will operate in air. Working assumptions: power
budget ~mW per channel, if the ASIC is to be operated in
vacuum cooling can be provided.

Data will be sparse.

Integral a.c. coupling and bias network for DSSSD.
 
Capabilities
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o Selectable Gain  low ~20GeV FSR (for stack front layer only)
                    :
                   intermediate (500MeV?) 
                    :
                   high ~20MeV FSR (for stack layers 2 to ... )
                   
                   measurement of low and high energy events

o Selectable threshold
  Minimum threshold < 50keV @ high gain
                    => rms noise < 5keV assuming threshold = 5 x sigma
                    
                    beta detection efficiency
                
o Integral and differential non-linearity 

                    spectrum analysis
                    calibration
                    threshold determination               

o Autonomous overload detection and recovery ~us

                    observe and measure short-lived activities

o Nominal signal processing time <10us

o Receive(transmit) time-stamp data

                    correlate events with other detector sub-systems
                    (gamma and neutron detector arrays)

o Timing trigger for coincidences with other detector systems
  time resolution << time stamp resolution
  
                    minimise random correlations

Timescale
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EPSRC grant submission:                 January 2006
EPSRC physics prioritisation panel:     April 2006
Project commencement:                   1 August 2006
Project prototype/commissioning:        2009/10
Experimental programme commencement:    2010/11