Halo affect

[Anonymous]

I was outside and was using a Compass Gold Scanner Pro in the snow and found a target was reading copper penny and it was 3inches and then I took my Minelab XS over it and it was some eractic in reading (as was the Compass) till I found the right angle to get it to lock and then it lock at the top of the screen near the right.
Ok i start digging and found a screw then I rechecked the whole and the reading was still there but not eratic neither detector would pick up the screw laying on the surface.I dug a little and was using a pinponter and it took me a little while but I found a Copper BB. I thought aint know way they picked that little thing up.
I took both detectors over the hole and nomore reading.So I took the detectors over the BB and they barely made a sound.I put the screw and BB side by side and nothing.I checked everywhere around that whole and moved the coil over to the right and got what I thought to be a zinc penny reading on both detectors and it was a pull tab at the surface it even read like a silver coin on the XS.I am sure I never passed over this tab when I circled around the hole I found the BB in but I can not figure out why I cannot detect nothing now.I was getting a good readin everytime from one angle and not so good from another.This ground is mineralized somewhat could I have been getting a halo affect when the objects where in the ground or is this one of those unexplainables.

 

[Anonymous]

lots of lookers but no suggestions...lol..it weirds me out,would like to know if this has happend to anyone else.

 

[Anonymous]

this kind of thing used to happen to me regularly. signal disappearing, etc. the problem is gone now that i use a periscope. it makes it easier to find even tiny pieces of metal. the periscope tip can be pushed into the soil several inches to find the target on the sides of the hole or down deep. it saves me time pinpointing too, because i don't have to fuss pin pointing with the detector, but only do a quickie and know the scope will find it fast.
as far as why solid signals disappear once you dig, i just don't know.

 

[Anonymous]

Rick;
The halo effect is a real phenomenon. Once the object is removed from the ground and the halo, it can fall below the detection limits of the machine. The Explorer is affected by "ground effects" in that it will pick up objects better in the ground than in air and the longer they are in the ground the stronger the signal. Even BB's will develop a halo just like the zinc pennies 18" down that will blow your ears off.
Rick (TN)

 

[Anonymous]

As you know any given piece of ground can be pretty complicated ... it can have fixed or variable mineralization, rock or other voids, different levels of moisture, frequently more than one target under your coil which can be a combination of good and/or bad targets, these targets can be at different depths / materials / alloy mixes / time in earth /locations / sequences / leech into the soil at different rates , etc, etc. There really is an infinite number of combinations and permutations. The discrimination circuitry usually is designed to be most accurate in the simpliest cases and any additional factors only complicate things and give these odd behaviours we all experience from time to time.
Fortunately for us most of these things don't happen all at once ;^) and usually they are simpler combinations of factors which allows the disc circuits to help us the majority of the time. There is always a risk of missing "good" targets and often some of the best finds are by those who use little or no disc.
That being said ... in the case you described above I wouldn't be surprized if the halo effect had an impact. Once you disturb the dirt this disappears and you can't re-create the effect to test it on the surface of the ground. Usually once you get the target to the surface and isolate it from other metal the disc circuit works perfectly (ie the screw won't respond). When put together one or the other targets could easily over-ride the effect of the other or result in a weird combined response???
These situations are just the nature of the beast and what makes detecting challenging 8^).
HH ... Gord.

 

[Anonymous]

I was pretty much coming to the conclusion you all gave me about distirbing the ground then the signal is gone.Lots of junk in this yard but it is teaching me real quick.I found out today that if I went wide open all metal I could pick up both the BB and the screw noproblem,even reburried them an could detect them that Halo effect is whats going on forsure...thanks again.