PROM 1 anti-personnel landmines Possibility of … · PROM 1 anti-personnel landmines Possibility...

EUROPEAN COMMISSION DIRECTORATE GENERAL JRCJOINT RESEARCH CENTREInstitute for Systems, Informatics & Safety

Technical note N° S.P.I.01.29

PROM 1 anti-personnel landminesPossibility of activation

by physical contact with a metal detector

Authors:Fernandez ManuelLewis AdamLittmann François

Ispra – March 2001

European Commission Joint Research CentreInstitute for Systems, Informatics & Safety

Technical note N° S.P.I. 01.29PROM1 activation by metal detectors

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Distribution ListJRCDavid WilkinsonAlois Sieber, John DeanFernand Sorel, Fivos AndritsosMartyn Dowell, Iain Shepherd

ISISISIS/TDPISIS/RITISIS/MIA

External to the JRCDaniela Dicorrado-AndreoniWolfgang Boch, Pascal Collotte , Jean Jacques LauturePeter Billing

DG RELEXDG INFSOECHO

Hans SchiebelOllie AllerheadGerhard VallonMartin FoersterTheodor Steinbuchel

SchiebelGuartelVallonFoersterEbinger

Jernej Cimpersek, Eva Veble ITFPat & Eddie Banks BiH Commission on DeminingFilip Filipovic BHMACDamir Gorseta CROMACJohn Flanagan UN MACC, KosovoArben Braha AMAE, AlbaniaJanko Petrovic CCPDRRobert Doheny, Jan Koster, Curt Larsson, David Lewis,Robert Suart, Steve Vermeer

ITEP ExCom

Kaj Horberg ITEP SecretariatGeorge Zahaczewsky U.S DoDHarold E. Bertrand IDADenis Reidy JUXOCOChristine Lee, Karin Breiter NVESDJacques Roosenboom MOD NetherlandsArnold Schoolderman TNOPieter Jan de Veer Test Department HemburgYogadhish Das, Jack D. Toews DRESRichard Beech, David Lewis DERA ChertseyAlastair McAslan, Paddy Blagden GICHDHemi Morete UNMASChristian Desmoulins, Denis Duret CEAClaudio Bruschini EPFLPasquale Nardone ULB



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Head of Unit

Name: Alois Sieber

Date: 19 March 2001

Signature: Original signed by Alois Sieber

Institute Director

Name: David Wilkinson

Date: 23 March 2001

Signature: Original signed by David Wilkinson

DisclaimerThis report is an investigation of a specific problem that may occur with metal mine detectors and one class of mine.Its purpose is to help to define safe operating procedures. It is not intended as a general statement of the relativemerits of different types or models of detectors.

Legal NoticeThe information in this document may not be disseminated, copied or utilized without the written authorization of theCommission. The Commission reserves specifically its rights to apply for patents or to obtain other protection for thematters open to intellectual or industrial protection.The distribution of this document is limited to the persons given in the distribution list.Neither the Commission of the European Communities nor any person acting on behalf of the Commission isresponsible for the use that might be made of the following information.



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Abstract

PROM 1 anti-personnel landminesPossibility of activation by physical contact with a metal detector

M. Fernandez, A. M. Lewis & F. LittmannEuropean Commission Joint Research CentreTP 272 Via E. Fermi 1, Ispra (VA) 21020 Italy

AbstractMeasurements of the horizontal detection distance of a VPROM1 inert mine have been madewith five different models of commercial metal detectors, two having differential coils and threehaving non-differential coils, in air and in highly magnetic soil, with the heads horizontal andtilted. The VPROM1 is the training version of the PROM1 antipersonnel boundingfragmentation mine.The measurements were made in response to a request by a demining agency, which suspectedthat some fatal accidents involving activation of PROM1’s had been due to physical contact of ametal detector with the protruding pronged fuze. It was thought that the presence of regions ofreduced sensitivity straight in front and behind the head of a differential coil detector hadprevented the detector giving its alarm sound early enough to provide adequate warning. In thework reported here, horizontal detection distances at prong height of the order of 10cm wererecorded. Significant reductions in detection distances were found in sectors 30º wide.No similar effect was found for the non-differential coil detectors. The results are thereforeconsistent with the above hypothesis. The waveform of the detector current appeared to play nopart. Highly magnetic soil had only a small effect.All the detectors, including those with differential coils, were sufficiently sensitive to make itpossible to detect the PROM 1 in a preliminary sweep, made well above the prong height.



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Contents

1 Introduction......................................................................................... 6

2 Experimental Measurements ............................................................. 82.1 The aim ........................................................................................................................................................ 82.2 The metal detectors...................................................................................................................................... 82.3 The target ..................................................................................................................................................... 92.4 The method ................................................................................................................................................ 102.5 The tests ..................................................................................................................................................... 13

3 In-air & In-soil Main Measurements .............................................. 143.1 Ebex 420 PB .............................................................................................................................................. 143.2 Foerster Minex 2FD 4.500......................................................................................................................... 163.3 Guartel MD8.............................................................................................................................................. 183.4 Schiebel AN-19 ......................................................................................................................................... 213.5 Vallon ML 1620C...................................................................................................................................... 23

4 Tilt measurements on the differential detectors ............................ 254.1 The aim ...................................................................................................................................................... 254.2 The method ................................................................................................................................................ 254.3 The results.................................................................................................................................................. 25

5 Verification of minimum sweep height ........................................... 285.1 The aim ...................................................................................................................................................... 285.2 The method ................................................................................................................................................ 285.3 The results.................................................................................................................................................. 295.4 Recommendation ....................................................................................................................................... 29

6 Additional Observations................................................................... 30

7 Conclusions ........................................................................................ 31

8 Annex.................................................................................................. 338.1 References.................................................................................................................................................. 338.2 Acronyms................................................................................................................................................... 348.3 Measurement data ...................................................................................................................................... 35



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1 Introduction

The PROM1 is a bounding fragmentation anti-personnel mine (fig. 1.1) [1] with a very highmetal content (approximately 2500g) and a very powerful charge. It may be triggered bytripwires (fig. 1.2) and/or by contact with the four-pronged fuze. The activation mechanism isdescribed in [2]. After ignition, the body of the mine, including the main charge, is launched intothe air. At around 70cm the anchor cable (or tether wire) joining the bottom of the mine, whichstill remains in the ground, and the base of the main part of the mine body will be pulled taut.The resulting jar pulls a percussion cap onto a fixed firing pin, initiating the detonator and thenthe main charge. The mine is then shattered in all directions with an effective lethal range ofmore than 20m. The PROM1 is normally olive green, so that visual detection in grass is difficult.The total height of the mine is 26cm. In the standard Yugoslav National Army mode, it is buriedwith the prongs 11cm above ground level. A variant called the PROM PK was manufacturedfrom 1977, the most important modification being the reduction of the tether wire length to20cm.

After several severe causalities caused by PROM1 mines on deminers, the EuropeanCommission Joint Research Centre was approached by Mr Eddie Banks, Technical Advisor tothe Bosnia and Herzegovina Commission for Demining [3]. In an accident investigation reportfor the US State Department, Mrs. Pat Banks had proposed a mechanism, which might havecaused such accidents. She suggested that there was a region of low sensitivity ("weak spot") atthe front of the halo of some metal detectors, where the detection range was significantlyreduced, even for high metal-content mines. If such a detector were swept in a forward motion, asignal would not be audible until its head was extremely close to the prongs of a PROM1. Theoperator would be unable to assess the danger before contact with the mine fuzetrigger.Mr and Mrs. Banks asked the JRC to see if this mechanism could be confirmed or refutedscientifically.

A multi-national technical evaluation of performance of commercial off the shelf metal detectorsin the context of humanitarian demining has recently been completed – the International PilotProject for Technology Co-operation Consumer Report (IPPTC) [4]. However, all targets used inIPPTC had a very low metal content compared to the PROM1, so that the results are not directlypertinent to this case and additional work was needed.



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Figure 1.1: PROM1 Figure 1.2: Fuze and tripwire



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2 Experimental Measurements

2.1 The aimTo assess the level of risk that the mine might be triggered in the search process, the keyparameter to know is how close the head can get to the mine, before the operator receives analert from the detector. This technical note documents the experiments that were performed atthe JRC to measure this distance, for various detectors under different conditions.

2.2 The metal detectorsThree metal detectors were loaned by Mr Banks [5] which had been used by a commercialdemining contractor in Bosnia and Herzegovina (BiH). In order to have a larger spectrum ofsensors, the JRC also used three of its own detectors. The following table provides the overviewof all metal detectors examined (fig. 2.2.1).

Detector BiH JRC Serial Number

Ebinger Ebex 420 PB X 2494

Foerster MINEX 2FD 4.5000 X 1666452 172

Guartel MD8 X X 005499 & 990721

Schiebel AN 19/2 X 78319

Vallon ML 1620C X 104

Figure 2.2.1: The metal detectors in front of the Gauss Laboratory



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2.3 The targetA VPROM1 (fig. 2.3.1) was used to realize the tests. The VPROM1 is an inert training versionof the PROM1. Externally, it is a geometrical replica of the PROM1, has a similar mass of metaland is free from explosive. The internal structure (fig. 2.3.2) differs somewhat from that of theworking mine. This will have no effect on the measurements because the electromagneticpenetration depth in steel for metal detectors is only a fraction of a millimetre, much less than thewall thickness. Essentially, the detectors see the external surface of the mine. The VPROM1 withits model fuze weighs 2 360g.

Figure 2.3.1: VPROM1 Figure 2.3.2: VPROM1 and inner simulant part



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2.4 The methodThe experiment was conducted at the Carl-Friedrich Gauss Laboratory of the Unit forTechnologies for Detection and Positioning at the Joint Research Centre in Ispra (Italy). Thelaboratory is a non-metallic building designed specifically for tests on mine detectors sensitive tometal [6]. The measurement method is described below and was generally the same for all metaldetectors. Specific details are given for each detector.

Step 1: Set upA VPROM1 was placed upright on the ground, far from any metallic object.Above the mine, a square plastic board (fig. 2.4.1), transparent to metal detectors, was placedhorizontally at a known height. A millimetric graph paper sheet was taped on the board, with thecentre of the sheet located exactly above the prongs of the VPROM1. Starting from the centre,radial lines were drawn every 15°.The altitude referred to below for each test is taken between the upper part of the plastic boardand the upper part of the prongs (fig. 2.4.2) of the mine.

Step 2: CalibrationThe detectors were first calibrated, in order to allow the sensitivity setting always to be restoredto the same level, even if the detector drifted, was switched off or was adjusted in error.The sensitivity of the detector was set to the almost highest possible level, the detector being faraway from any metal object. The sensitivity was then reduced until no more sound was audible.The detector was brought near to the calibration object: a non-magnetic, stainless steel sphere ofdiameter 19mm (fig. 2.4.3). The sphere is mounted in the cream-coloured silicone-rubber block.The maximum height at which this sphere could be detected with each detector was thenrecorded (fig. 2.4.4).Note: For the differential detectors, for which no continuous adjustment was available, thecalibration sphere detection height varied by around ± 10% from day to day.

Step 3: The horizontal detection distancesFor each selected altitude (–2cm, 8cm and +18cm), the entire board was scanned in the followingmanner. Starting from the edge of the paper, the search head was slowly moved forward towardsthe mine, so that the centre of the coil followed one of the 15º radial lines (fig. 2.4.5). Thedetector was stopped at the point where its alarm first sounded and its position (intersection ofthe radial line and the edge of the coil closest to the mine) was marked. The plotted linestherefore show the separation between coil and mine – not the locus of the centre of the coil. Theprocess was repeated for each radial line, all around the mine (fig. 2.4.6). The orientation of thedetector with respect to the paper was kept the same for all lines; that is to say, the handle alwayspointed in the same direction.The altitude was then changed and the operation repeated.Note: Between the point where the first alarm sounded and a clear continuous sound, it wasfrequently necessary to move the head a few centimetres further towards the mine target. Theplots correspond here to the first initial sound even if hesitant.



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Figure 2.4.1: The VPROM1 below theplastic board

Figure 2.4.2: Altitude above the prongs

Figure 2.4.3: Reference steel sphere insilicone-rubber block

Figure 2.4.4: Calibration



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Figure 2.4.5: Measuring method(the centre of the search head tracking the radial lines in the direction of the target)

Figure 2.4.6: Example with the Guartel MD8



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2.5 The testsTwo main series of measurements were made:

• First in air inside the Gauss laboratory at various altitudes above the prongs (-2, 8 &18cm).

• Then outside, with the VPROM1 target partially buried in a highly magnetic soil fromNaples (fig. 2.5.1 & 2.5.2), to a depth of 17.5cm (the fuze trigger protruded 8.5cm abovethe soil). The in-soil measurements were made only at one altitude of 18cm.

Additional measurements were made to check the effect of tilting the search head of thedifferential detectors, at the altitude of 8cm:

• Roll (10°, 20°).• Pitch (-10°, 10°).

Finally, measurements of the maximum vertical height detection in the highly magnetic soil weremade to confirm that it was possible to detect the mine safely above the prongs.Precision:

• The error in the measurements of the detection distances is estimated at ± 20mm,including the error in the placement of the mine, the error due to the subjective nature ofthe limit (sound) and reading of the calibration sphere detection height.

• The error in maintaining the constant yaw angle of the search head is estimated at ± 5°.• For the differential detectors for which no continuous adjustment was available, the day

to day repeatability of the horizontal detection distance is around ± 10%, proportional tothe day to day calibration drift.

Figure 2.5.1: VPROM1 buried in the highlymagnetic soil

Figure 2.5.2: In-soil measurement



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3 In-air & In-soil Main Measurements

3.1 Ebex 420 PB

Figure 3.1.1: Ebex420 PB

Figure 3.1.2: Search head Figure 3.1.3: Control box

Preliminary remark: The Ebex 420 PB loaned from Bosnia-Herzegovina did not always maintainconstant sensitivity and it was necessary to recheck the calibration frequently.

Detector principle:The Ebex 420 PB is a pulsed induction single receiving coil detector, without auto-zero [7].The shape of the search head is oval, length 26cm & width 15cm.

Calibration sphere detection height: 19cm

Sensitivity control:Continuous adjustment, without any pre-selectable positions marked.

Special details of method:The heads of all the detectors tested are designed to partially rotate about a horizontal axis (pitch)so that the handles can be held at a convenient slope with the head horizontal. Since the Ebex420 has a metal shaft, the calibration is affected by changing the head angle in this way.Therefore, care was taken not to alter the head angle during the test. All the other detectors usedin this study have non-metallic shafts attached to the head.

Results:The horizontal detection distance graphs are all almost circular (fig. 3.1.4). At the altitude of-2cm, the horizontal detection distance is around 35cm. The detection range measured in highlymagnetic soil was greater (fig.3.1.5), but not significantly so.

Summary:The Ebex 420 PB tested detects a VPROM1 with a sufficient safety margin at all angles.



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Figure 3.1.4: Horizontal detection distance with sketch showing orientation and scale of head

Figure 3.1.5: Comparison between in-air and in-soil measurement

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3.2 Foerster Minex 2FD 4.500

Figure 3.2.1: FoersterMinex 2FD 4.500

Figure 3.2.2: Search head Figure 3.2.3: Controlbox

Detector principle:The Foerster Minex 2FD 4.500 is a continuous induction, differential receiving coils detector,with auto-zero [8]. The shape of the search head is elliptic, length 29cm & width 21cm.

Note: The differential arrangement of the search head coil is designed to help in an accuratepinpointing of a target, by producing a null when the middle axis of the search head is in front,above or behind the target.

Calibration sphere detection height: 19 to 23cm

Sensitivity controls:Three selectable positions (maximum sensitivity, position H, was used).

Special details of method:This detector displayed drift of the zero: i.e. it continued to beep after withdrawal from the mine,so it was necessary to manually zero between two sweeps. The signal begins with a very lowvolume, so the detection decision threshold was more subjective than for the other detectors.

Results:The horizontal detection distance graphs (fig. 3.2.4) showed a loss of sensitivity in the front (andbehind) the search head. Between -30° and +30°, there is a noticeable reduction of the detectionrange at all heights. The maximum loss of sensitivity is around –5° and +5° taking into accountthe precision on the constant yaw angle of the search head. For the altitude of 18cm, no signal atall was heard when scanning in a forward direction (0°). For the altitude of -2cm, the horizontaldetection distance at 0° and 180° is around 14cm.The detection range measured in highly magnetic soil is almost unchanged (fig. 3.2.5).

Summary:The Foerster Minex 2FD 4.500 tested detected the VPROM1 but showed regions of reducedsensitivity in front of and behind the search head.



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3.3 Guartel MD8

Figure 3.3.1: Guartel MD8 Figure 3.3.2: Search headwith a white line on thesighting bar

Figure 3.3.3: Control functions

Preliminary remark: The MD8 loaned from Bosnia-Herzegovina (s/n 005499) was not usedbecause it tended to sound continuously, even in the total absence of metal, and also had anexcessive tendency to auto-zero. Instead, the JRC’s MD8 (s/n 990721) was used in the test.

Note: The differential arrangement of the search head coil is designed to help in an accuratepinpointing of a target, by producing a null when the middle axis of the search head is in front,above or behind the target.

Detector principle:The Guartel MD8 is a pulsed induction, differential receiving coils detector, with auto-zero [9].The shape of the search head is circular, diameter 32cm.

Calibration sphere detection height: 19 to 22cm

Sensitivity control:Three selectable positions (maximum sensitivity, position III, was used).

Special details of method:The sound from the MD8 is not sustained when it is held immobile above a metal piece, butvanishes as the detector automatically re-zeroes. The head was therefore swept fast enough toavoid the detector zeroing-out while it approached the target. The detection limit was markeddirectly after the beginning of the beep. Since it was more difficult to measure the detection limitwhen the head was moving, the measurements were repeated several times for accuracy.



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Results:The horizontal detection distance graphs (fig. 3.3.4) showed a loss of sensitivity in the front (andbehind) the search head. Between -30° and +30°, there is a noticeable reduction of the detectionrange at all heights. The maximum loss of sensitivity is around –5° and +5° taking into accountthe precision on the constant yaw angle of the search head. For the altitude of 18cm, no signal atall was heard when scanning in a forward direction (0°). For the altitude of -2cm, the horizontaldetection distance at 0° is 8.5cm and 5.6cm at 180°.The detection range measured in highly magnetic soil is almost unchanged (fig. 3.3.5).

Remark:In the detector manual [9], the manufacturers note the presence of the region of reducedsensitivity and draw attention to the possibility of making use of it as a feature:“The halo search head is of differential detection design. That is, it tends to reject targets outsidethe halo loop. The maximum rejection of outside targets is in line with the white line on thesighting bar and minimum at right angles. In this way a small target may be detected under thesearch halo with a large target close to (150 mm) the halo in line with the sighting bar”.

Summary:The Guartel MD8 tested detected the VPROM1 but showed regions of reduced sensitivity infront of and behind the search head.



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3.4 Schiebel AN-19

Figure 3.4.1: Schiebel AN-19/2


Detector principle:The Schiebel AN-19/2 is a pulsed induction single receiving coil detector, without auto-zero[10]. The shape of the search head is circular, diameter 26cm.


Sensitivity control:Continuous adjustment, no pre-selectable positions marked.

Special details of method:None.

Results:The horizontal detection distance graphs are all almost circular (fig. 3.4.4). At the altitude of-2cm, the horizontal detection distance is more than 35cm. The detection range measured inhighly magnetic soil was smaller (fig. 3.4.5), but not significantly so.

Summary:The Schiebel AN 19/2 tested detects a VPROM1 with a sufficient safety margin at all angles.



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3.5 Vallon ML 1620C

Figure 3.5.1: Vallon1620C


Detector principle:The Vallon ML 1620C is a pulsed induction single receiving coil detector, with auto-zero [11].The shape of the search head is elliptic but slightly flattened, length 30cm & width 17cm.


Sensitivity controls:Continuous adjustment with graduated scale – set to 6 out of 7.Two current levels: set to mode P (upper level).Internal switches: set to 1 (normal soil) and 5 (50Hz filter).

Special details of method:The above settings were selected because they give maximum sensitivity, in accordance with theprotocol. The in-soil test was also repeated at the mineralised soil setting (2). Note that inpractice it would not be known in advance that a PROM 1 is present, so the current would notnecessarily have been reduced to M mode. With the above settings, the detector is very sensitive,as indicated by the calibration height.The signal vanishes when the detector is immobile over the mine due to auto zeroing. The VallonML 1620C does not give a signal when it is removed from the mine after it has auto-zeroed.

Results:The horizontal detection distance graphs are all almost circular (fig. 3.5.4). At the altitude of-2cm, the horizontal detection distance is more than 45cm. The detection range measured inhighly magnetic soil (position 1 & 2) was smaller (fig. 3.5.5), but not significantly so.

Summary:The Vallon ML 1620C tested detects a VPROM1 with a sufficient safety margin at all angles.



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Figure 3.5.5: Comparison between in-air and in-soil measurement(with (2) and without (1) magnetic switch on)



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4 Tilt measurements on the differential detectors

4.1 The aimIn a field situation, the deminer would not necessarily have the detector exactly in a horizontalplane with respect to the mine body, especially since the angle at which the mine is buried mayvary. Therefore, tests were conducted on the differential coil detectors to determine the effect oftilting of the head (roll & pitch) on the sensitivity patterns, to find out if the regions of reducedsensitivity were enlarged, reduced or moved substantially.Note: it was unnecessary to twist about the third axis, the yaw axis, since a rotation about thisaxis is implicit in all the plots already available.

4.2 The methodA small plastic block was taped to the underside of the head of each detector, so that the headrested at an angle when placed on a flat surface. The angle was calculated from the position ofthe block and its height to an estimated precision of ± 10%. All these tests were conducted in air,at an altitude of 8cm above the prongs, using the same method to measure the horizontaldetection distance.

The following angles were used:Axis Angleroll +10 °roll +20 °

pitch +10 °pitch -10 °

4.3 The resultsTilting the head in the roll axis (fig. 4.3.1 & 4.3.2) by 10 ° and 20 ° tended to move position ofthe reduced sensitivity regions in the direction of the tilt but the minimum horizontal detectiondistances remain almost at the same level.Tilting the head by 10 ° in the pitch axis (fig. 4.3.3 & 4.3.4) had no clearly discernible effect,within the precision of the measurement, for either detector.The argument that there is a risk associated with the reduced sensitivity regions is therefore notaffected by the possibility that the head or mine might be tilted.

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Figure 4.3.1: Tilt test for the Guartel MD8 – roll axis

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Figure 4.3.2: Tilt test for the Foerster Minex 2FD 4.500 – roll axis



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10°


for different pitch angles (+ front up, - front up))Altitude 8 cm

Fig 4.3.3: Tilt test for Guartel MD8 – pitch axis

0102030405060

180°165°

150°135°

120°

105°

90°

75°

60°

45°30°

15°0°

-15°-30°

-45°

-60°

-75°

-90°

-105°

-120°

-135°-150°

-165°0°

-10°

10°


for different pitch angles (+ front up, - front up))Altitude 8 cm

Fig. 4.3.4: Tilt test for Foerster Minex 2FD 4.500 – pitch axis



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5 Verification of minimum sweep height

5.1 The aimThe existence of a risk associated with the low sensitivity regions of the differential coildetectors is confirmed by the experiments above. It is therefore important to consider how a safeoperating procedure might be defined, where mines of this pattern are known or suspected to bepresent.Since the PROM 1 contains a large amount of metal, it is detectable from relatively large heights.Therefore, it is possible in principle to search for PROM 1 mines in a preliminary sweep,conducted at a height great enough to avoid the risk of touching the prongs. Having made thepreliminary sweep, the deminers could then go on to sweep close to the ground to detectminimum metal mines.A test was conducted to verify that detection at a safe height in this manner was possible for alldetectors (fig. 5.1.1).

Figure 5.1.1: Sweep above the VPROM1 prongs in highly magnetic soil

5.2 The methodThe Guartel MD8 and Foerster Minex 2FD 4.500 have both three positions of sensitivity, givingapproximately the same calibration heights for the two detectors. In order to get equivalentsettings, the other detectors were adjusted to similar sensitivity, using the calibration spheredetection height as described above.The VPROM1 was buried in the magnetic soil with the prongs protruding 11 cm above thesurface as in the Yugoslav Army Mode. The detection heights were measured to a precision ofabout ±20mm, which is sufficient for the purpose intended.



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The Vallon ML 1620C was set for the lower current level (setting M) and for lightly mineralisedsoil (internal switch position 2), consistent with what might reasonably be used in conducting ageneral preliminary sweep.It was not necessary to use the ground learning button on the Foerster Minex 2FD 4.500.Note: This test is not intended to compare generally the performance of one detector againstanother, for which purpose a higher level of precision and a larger number of targets andconditions are required. Again, we refer the interested reader to the IPPTC report [4].

5.3 The resultsAll the detectors detected the mine at least at (fig. 5.3.1):

• 40cm above the soil (29cm above the prongs) for the highest sensitivity setting.• 30cm above the soil (19cm above the prongs) for the medium sensitivity setting.• 20cm above the soil (9cm above the prongs) for the minimum sensitivity setting.

Figure 5.3.1: Detection heights for VPROM1 in highly magnetic soil

5.4 RecommendationIt would be therefore feasible to make a preliminary sweep at a height of about 20cm above thesoil on a medium sensitivity setting. In this way, any PROM1 present would be safely detectedbut without picking up the small metal object. Then another sweep, at a lower height, will beneeded to detect mines with lower metal content.

Height above the soil(the prongs are protuding 11 cm above the soil)

0

10

20

30

40

50

60

High Medium Low

cm

Schiebel

Guartel

Vallon

Foerster

Ebinger



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6 Additional Observations

In addition to the question of the sensitivity pattern, which was the main object of thisinvestigation, we wish also to mention here some other possible aggravating factors:

• Two of the detectors brought from BiH and loaned to us (MD8 and Ebex 420 PB) hadpoor electronic performance. In particular, the field-used MD8 performed much worsethan the JRC’s example, which has been used mainly in laboratories and, on average, foronly a few hours a month. We do not know if the examples loaned to us arerepresentative of detectors currently in field use, or are unusually bad. The results doconfirm the need to test on a regular basis the performance of detectors used in the fieldin order to avoid possible hazards arising from circuits or coils deteriorating afterprolonged use in harsh conditions.

• The design and placement of the detector controls should not be overlooked. It might bepossible for a detector to be manually re-zeroed accidentally for example. If the manualzero-reset is positioned under the user’s thumb, where it is very easy to push by accident,a possible hazard arises (fig. 6.1), especially if the detector gives no indication that it hasbeen re-zeroed.

• Automatic re-zeroing could also be hazardous, but only if the detector was movedextremely slowly, so that the target was zeroed-out, rather than detected.

• Another very significant hazard arises with mines of this type as a result of standardsearch protocols. When the deminer finds an indication of metal, it is common practice toattempt to pinpoint the source by making passes with the detector in two perpendiculardirections. A deminer following such a procedure would be likely to touch the prongs ofa PROM1 even if the detector had given the indication at a safe distance from the mine,especially if it was concealed in vegetation.

Figure 6.1: Manual zeroing button of MD8



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7 Conclusions

Differential receive coil metal detectors:• The measurements show that there are regions of reduced sensitivity in front and behind the

search head of the two differential coils metal detectors. The sensitivity pattern is clearlydescribed by the manufacturers in the relevant operator manuals and, in fact, highlighted as apotentially useful feature.

• In the work reported here, horizontal detection distances at prong height of the order of 10cmwere recorded. Significant reductions in detection distances were found in sectors 30º wide.

• The detectors use different current forms (pulsed and continuous wave) and have search headwith different shapes (circular and elliptic) but show similar loss of sensitivity.

• Tilting of the search head of the differential coil detectors had only a small effect on thesensitivity patterns. The regions of reduced sensitivity were moved but not significantly so.

• Highly magnetic soil had only a minor effect on the shape and size of the sensitivity graph.

Single receive coil metal detectors:• All the single receive coil metal detectors tested, detected the VPROM1 with a sufficient

safety margin at all angles, independently of the current forms and the shapes of the searchhead.

• Highly magnetic soil had only a minor effect on the shape and size of the sensitivity graph.

Observations:• The tests reported here were deliberately conducted with a sweep pattern different from that

recommended by the manufacturers, but which might conceivably occur in practice.• The state of maintenance of detectors after rigorous field use should not be overlooked as a

contributing factor in accidents. Two of the detectors loaned from BiH showed poorelectronic stability.

• There may be some risk of missing a mine due to accidental manual or automatic re-zeroing,depending on the design of the detector and the manner in which it is held and swept. Theimportance of matching Operating Procedures and training to the particular detector in use isespecially apparent from this observation.

• Despite the large metal content of the VPROM1, the “weak spots” in front and behind thesearch heads of the two differential coil metal detectors tested were large enough that itwould be possible to get very close to the prongs before the detector sounds. If a detector ofthis pattern were moved forward or backward towards a PROM1 at any realistic sweepingspeed and the search height matched the height of the mine prongs, a deminer would haveonly a fraction of a second to react before the mine was activated.

We consider that these results should be reflected in future operating and training deminingprocedures.



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Recommendations:• Differential receive coil detectors, with a coil format similar to those tested here, must be

swept laterally and not in a forward / reverse motion.• Personnel should be trained to follow the operating procedure recommended by the

manufacturer for the specific model of detector in use.• When the presence of PROM1’s is considered possible, the deminer should make a

preliminary sweep at a height of about 20cm above the soil on a medium sensitivity setting.In this way, any PROM1 present would be safely detected, without false alarms from smallmetal objects. Another sweep, at a lower height, should then be conducted to detect mineswith lower metal content.



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8 Annex

8.1 References

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[8]

[9]

[10]

[11]

Jane’s Mines and Mine ClearanceColin King (ed.) Third edition 1998-99Jane’s Information Group, Coulsdon, Surrey, UK

Brassey’s Essential Guide to Antipersonnel LandminesEddie BanksBrassey’s (London) 1997

Mrs. Pat and Mr Eddie BanksPrivate correspondence with JRCJuly11, 2000

International Pilot Project for Technology Co-operation Consumer ReportA multi-national technical evaluation of performance of commercial off the shelf metaldetectors in the context of humanitarian deminingDean. J. T., Zahaczewsky G., Das Y., Lewis D., Roosenboom J. (Editors),Joint Research Centre, Ispra, Italy, 2001

Loan of Metal Detectors from BiHMr Eddie BanksPrivate Correspondence with JRCOctober 5, 2000

http://www.tdp.sai.jrc.it/(Test and Evaluation Facilities)

Operators’ Manual for the Metal Detector EBEX 420 PBEbinger Prüf- und Ortungstechnik GmbH, Köln, Germany (undated)

Minex 2FD 4.5000 Compact Metal DetectorOperating InstructionsInstitute Dr Foerster, Reutlingen, Germany, 2000

MD8 Mine Detector Handbook – June 1999Guartel Ltd., London, UK, 1999

AN 19/2 Mine Detecting SetOperating ManualSchiebel, Vienna, Austria (undated)

Metal Mine Detector ML 1620 COperation Manual Issue 1/98Vallon GmbH, Eningen, Germany, 1998



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8.2 Acronyms

JRCIPPTCPROM1PROM PKVPROM1

Joint Research Centre of the European CommissionInternational Pilot Project for Technology Co-operation Consumer ReportAnti-personnel fragmentation bounding mine from the former YugoslaviaModified PROM 1 with reduced length tether wireTraining version of the PROM1 mine, has no explosive, almost the same metalcontent and a broad yellow band around the top of the mine body



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8.3 Measurement data

8.3.1 Ebinger In-air & In-soil

in-air in-soilEbinger -2cm 8cm 18cm 18cm

180° 34 29 27 29165° 35 30 27 30150° 35 30 28 30135° 35 33 29 30120° 39 33 29 33105° 39 33 30 3490° 38 33 28 3475° 38 33 27 3360° 38 32 26 3245° 36 31 25 3230° 36 31 25 3015° 35 30 25 300° 35 29 25 28

-15° 36 31 25 29-30° 37 31 27 29-45° 37 32 29 31-60° 39 33 31 32-75° 39 34 31 34-90° 37 33 31 34-105° 37 35 31 34-120° 36 35 31 34-135° 38 33 28 32-150° 35 31 27 31-165° 35 30 27 30



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8.3.2 Foerster In-air & In-soil

in-air in-soil roll roll pitch pitchFoerster -2cm 8cm 18cm 18cm 10° 20° -10° 10°

180° 13 7 0 6 22 25 15 14165° 32 29 19 22 29 29 29 24150° 37 35 31 29 36 33 36 33135° 40 37 33 35 36 35 42 37120° 44 40 35 40 38 36 43 40105° 45 43 39 37 39 38 42 4090° 45 41 36 39 39 35 40 4275° 47 40 35 34 39 35 41 4460° 45 41 33 31 39 38 39 4245° 39 37 30 33 37 32 37 3730° 36 35 27 26 34 28 32 3415° 32 27 19 24 29 27 23 280° 14 11 0 2 25 25 13 6

-15° 31 31 23 24 11 21 23 27-30° 37 34 30 31 35 33 32 34-45° 41 41 34 39 41 40 34 39-60° 44 43 38 40 41 42 38 42-75° 43 40 37 40 41 41 39 39-90° 45 41 35 39 38 40 41 39-105° 46 43 38 36 41 41 38 38-120° 45 43 37 37 38 36 43 40-135° 42 41 31 30 38 37 39 38-150° 39 34 27 29 31 25 34 35-165° 32 30 21 19 8 16 29 27



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8.3.3 Guartel In-air & In-soil

in-air in-soil roll Roll pitch pitchGuartel -2cm 8cm 18cm 18cm 10° 20° -10° 10°

180° 6 3 0 0 22 25 7 7165° 28 18 8 12 29 27 24 23150° 32 30 22 18 32 28 30 29135° 34 32 24 22 35 30 34 34120° 36 32 26 23 45 31 34 35105° 35 33 28 29 43 30 36 3690° 35 33 28 28 41 30 32 3275° 35 34 29 27 43 30 33 3360° 36 34 28 25 48 30 34 3545° 36 33 26 25 42 30 32 3430° 33 26 22 18 27 29 28 2815° 29 21 16 11 24 26 23 240° 8 5 0 0 18 21 6 3

-15° 27 22 10 10 10 14 23 22-30° 33 28 17 18 24 14 29 29-45° 36 32 24 24 31 29 32 32-60° 37 33 27 25 31 30 33 33-75° 36 33 27 26 29 28 33 33-90° 36 33 26 26 29 30 33 33-105° 35 34 25 25 30 32 34 34-120° 36 33 26 24 32 30 33 33-135° 36 33 27 23 27 26 35 35-150° 32 29 23 20 26 9 32 34-165° 27 20 11 16 8 18 25 25



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8.3.4 Schiebel In-air & In-soil

in-air in-soilSchiebel -2cm 8cm 18cm 18cm

180° 35 34 30 30165° 34 33 32 30150° 32 33 30 29135° 33 33 30 28120° 34 34 31 29105° 33 33 29 2890° 33 33 29 2875° 35 33 28 2660° 35 34 29 2545° 36 34 29 2530° 36 36 30 2515° 37 35 30 250° 36 34 29 24

-15° 36 35 32 30-30° 37 35 31 30-45° 36 35 31 29-60° 34 34 30 29-75° 36 35 30 28-90° 34 34 30 27-105° 37 35 30 26-120° 33 33 29 26-135° 36 34 30 25-150° 35 34 28 24-165° 35 34 30 24



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8.3.5 Vallon In-air & In-soil

in-air in-soil 1 in-soil 2Vallon -2cm 8cm 18cm 18cm 18cm180° 48 45 44 41 36165° 49 45 43 41 36150° 53 52 48 47 32135° 56 53 48 50 35120° 54 53 53 49 37105° 53 52 50 43 3990° 52 49 48 45 4075° 50 48 47 42 4060° 53 50 49 41 3545° 50 47 45 39 3130° 53 52 48 36 2915° 48 44 43 35 290° 46 43 41 36 27

-15° 46 44 42 37 29-30° 49 50 44 44 30-45° 51 49 47 43 35-60° 49 52 51 47 36-75° 47 48 46 45 40-90° 46 48 45 42 40-105° 47 49 47 44 39-120° 50 51 48 47 37-135° 52 50 49 47 35-150° 53 52 44 47 34-165° 49 44 44 43 36



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8.3.6 Sweep heights

Position Calibration(cm)

Height (cm) Altitude (cm)

Ebinger 23 50 3914 35 247 25 14

Foerster H 23 42 31M 19 35 24L 14 32 21

Guartel III 22 41 30II 12 31 20I 6 21 10

Schiebel 20 50 3914 45 347 30 19

Vallon 23 50 3914 38 277 25 14

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