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Users Guide for the Operational Dosimeter DMC
What is the purpose of an operational dosimeter?
The operational dosimeter (DMC) is an electronic dosimeter. It is worn in addition to the « passive »
personal dosimeter and allows you:
• to display your integrated dose in real time,
• to warn you with a beep of variable frequency of the radiation level around you
• to inform you when the alarm thresholds are exceeded :
o DMC2000 (cf. : Figure 1) : alarm and indicator light,
o DMC3000 (cf. : Figure 1) : alarm, indicator light and vibration,
• to register your operational dose to allow a daily Radiation Protection follow-up of your
interventions.
DMC 2000
DMC 3000
Figure 1: Photos of the two types of DMC used at CERN.
The alarm threshold for the dose rate is fixed at 2 mSv/h (corresponding to the dose rate limit in a Limited
Stay Controlled Radiation Area).
The dose alarm thresholds are fixed by the Radiation Protection Group according to the regulationary
annual limits and the dosimetric estimations registered in IMPACT activities.
If you hear an alarm, you must leave the area immediately and contact the Radiation Protection Service
on the site concerned:
- Meyrin : 72504
- Prévessin, SPS, LHC : 75252
Where do you have to wear an operational dosimeter?
Wearing a DMC is obligatory for all access to Limited Stay Controlled Radiation Areas and High-Radiation
Controlled Areas (cf.: Figure 2), from now on called Controlled Radiation Areas:
Figure 2: Controlled Radiation Areas where wearing a DMC is obligatory.
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How do you wear your operational dosimeter?
The DMC, just like the « passive » personal dosimeter(s) is worn at chest level.
How to use an operational dosimeter?
Until the month of March 2013:
At the entrance of Controlled Radiation Areas, you will find a form specifically for the registration of
received doses during the intervention (cf.: Figure 3). Every time you access the area, you must fill in a line
and complete every column. The DIMR number is replaced by the IMPACT number.
Figure 3: dosimetric registration sheets
New! From the month of March 2013 onwards:
A new automatic reading system for the DMCs has been put in place for the start of LS1 (cf.: Figure 4).
Figure 4: new system for automatically reading the operational dosimeters
The dose displayed by the DMC is expressed
in milli-sievert (mSv). In the example below,
one can read 0.468 mSv which is the
equivalent of 468 micro-sievert (µSv).
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RESET your DMC to use it with the new reader stations
Once the new system is working a confirmation email will be sent to you by the Dosimetry Service. The
paper sheets will be taken away and you should then proceed to RESET your operational dosimeter at
one of the new reader stations.
You will find the new DMC reader stations at the entrance of Controlled Radiation Areas. To reset your
operational dosimeter, you should simply insert it into the reader station. When you take it out, the screen
of your dosimeter will no longer display the dose but your CERN identification number (« CERN ID »).
The dosimeter will then be operational and can be used with the new system; it will be in “pause mode.”
(cf.: Figure 5).
Figure 5: resetting your dosimeter
How to use the new reader stations?
At every access to a Controlled Radiation Area, you must IMPERATIVELY start your dosimeter by using the
reader station which is found near the access door to the area.
For this, before you enter the area you must:
• insert the DMC into the reader,
• type in your IMPACT activity code (numeric keypad) and press « ENTER »,
• check your DMC is working (mode « DOSE »)
When leaving the area, you must read your dosimeter by inserting it into the same reader. The DMC will
switch to mode « PAUSE » (inactive) and will display your CERN identification number; the dose received
during the work carried out is registered.
Figure 6: How to use the new reader system for DMCs
BEFORE
AFTER
RESET
Before
Accessing
Start your
DMC
Type your
# IMPACT
DOSE Access
Exit
Reading
PAU SE
Dose
Cern ID
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In case of a problem
In case of an alarm, you must leave the area immediately and contact the Radiation Protection Service
for the concerned area:
- Meyrin, tel. : +41 22 76 72504
- Prévessin, SPS, LHC, tel. : +41 22 76 75252
In case of a technical problem with the operational dosimetry system (battery problems, DMC HS, DMC HS
reader, etc….) please contact the Dosimetry Service:
- Tel. : +41 22 76 70538
- operational.dosimetry@cern.ch
If you do not know your IMPACT number, please contact your supervisor.
How to obtain an operational dosimeter?
Henceforth, the DMC is assigned by name. It is forbidden to share the operational dosimeter with your
colleagues; it can no longer be lent to others.
From now on the DMCs are distributed in building 55 by the Dosimetry Service:
- Tel. : +41 22 76 70538
- operational.dosimetry@cern.ch
- Hours: 8:00 – 11:30 and 13:30 – 16:00.
To obtain a DMC, you must go in person to building 55 (see figure 4).
Figure 7: situation of building 55.
To obtain a DMC permanently, it is imperative that you have validated the following points:
• you have obtained a CERN personal dosimeter (DIS) from the Dosimetry Service,
• you intervene in a Controlled Radiation Area at least twice a month.
Special cases: for specific interventions, a dosimeter will be assigned to you for the length of your
interventions. It must be taken back to building 55 immediately after the end of the interventions.
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