OBJECT     = INSTRUMENT
INSTRUMENT_HOST_ID             = VEGA2
INSTRUMENT_ID                  = DUCMA

OBJECT     = INSTRUMENT_INFORMATION
INSTRUMENT_NAME                = "DUST PARTICLE COUNTER AND MASS ANALYZER"
INSTRUMENT_TYPE                = "PARTICLE COUNTER"
INSTRUMENT_DESC                = "
 The detector is a 28 Km thick film of polarised polyvinylidene fluoride (PVDF),                                                  
covered on each face with a metallic conducting coating. A dust particle impacting the                                            
detector will displace a small volume of polarised material in the bulk of the detector,                                          
which then results in a fast depolarisation signal whose amplitude is a known function                                            
of the particle mass and velocity. Electronic circuits measure the pulse height and ac-                                           
cumulate pulse events above four different threshold levels. Since the relative impact                                            
velocity is known (i.e. the comet-spacecraft velocity), the mass is determined direct-                                            
ly from the known mass/velocity relationship for these detectors.                                                                 
 The detector assembly consists of the dust detector (M),
and a small anti-coincidence detector (V), mounted perpendicular to the direction of                                              
arrival of the dust particles. The purpose of the small detector is to detect very large                                          
mechanical shocks on the spacecraft which might trigger the most sensitive level of                                               
the dust detector.                                                                                                                
 Further technical details are given in the table below, where the values for
the 'differential dust mass ranges' are published in Simpson et al. 'Ducma
Measurements of Comet Halley Dust Mass Spectra Bases on Post-Encounter Dust
Calibrations', Asteroids, Comets, and Meteors III (1990, Uppsala).
 This instrument was selected one year before launch and could still be considered
at this late stage because it did not require any direct telemetry or telecommand inter-                                          
face with the spacecraft. Its inclusion was facilitated because it was allowed to share                                           
the data format and telecommands initially allocated to the ING instrument.                                                       
                                                                                                                                  
-----------------------------------------------------                                                                             
Table. Dust Particle Detector and Mass
Analyser characteristics                                                                                                          
                                                                                                                                  
Impact detector           28 micro m**2 PVDF foil                                                                                 
Detector area             75cm**2                                                                                                 
Maximum count rate        10**5/s                                                                                                 
Differential dust mass
range
                          1.5x10**-13 to 5.6x10**-11 g,
                          5.6x10**-11 to 1.6x10**-9 g,
                          1.6x10**-9 to 4.0x10**-8 g,
                          and greater than 4.0x10**-8 g

Integral dust mass range   >4.0x10**-8 g
Integration time for flux                                                                                                         
measurements at                                                                                                                   
encounter                  1 s
------------------------------------------------------                                                                            

"

END_OBJECT = INSTRUMENT_INFORMATION                      

OBJECT     = INSTRUMENT_REFERENCE_INFO
REFERENCE_KEY_ID               = "ESA-SP1066"
END_OBJECT = INSTRUMENT_REFERENCE_INFO

END_OBJECT = INSTRUMENT