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Re: [Microscope] Scintillation questions

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  • DonH
    Hi, This is what you want--and it s cheap. (URL may wrap) http://unitednuclear.com/index.php?main_page=product_info&cPath=2_76&products_id=506 Good luck, Don
    Message 1 of 19 , Jul 3, 2010
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      Hi,

      This is what you want--and it's cheap. (URL may wrap)

      http://unitednuclear.com/index.php?main_page=product_info&cPath=2_76&products_id=506

      Good luck,
      Don
    • Randall Buck
      Don has it right, the combination of a radioactive source, a phosphor screen and a low power optical magnification is called a spinthariscope. However, having
      Message 2 of 19 , Jul 3, 2010
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        Don has it right, the combination of a radioactive source, a phosphor screen
        and
        a low power optical magnification is called a spinthariscope. However,
        having a variable
        power optical magnification should prove to be more interesting.

        In the customary, historical form, the radioactive source is an alpha
        particle emitter, such
        as the common Americium 241 isotope or the harder to find Radium or the
        dangerous Polonium. The
        phosphor screen is a thin coating of Zinc Sulphide which has been doped with
        Silver, ZnS(Ag),
        applied to a transparent substrate. The alpha particles will be stopped by
        the substrate so the
        coated side should be exposed to the radioactive source while the microscope
        can be focused through
        the substrate. Eyes must be dark adapted prior to viewing the flashes that
        occur when an alpha
        impacts the screen.

        Radioactive sources must be handled with great care -- distance and
        shielding are the watchwords.
        Use rubber gloves and tweezers.

        Alpha particles have a range in air of a few centimeters so the source to
        screen distance should not be
        greater than that.

        The tritium source is a Beta particle (electron) emitter with an electron
        sensitive phosphor.
        In principle, this should function as a spinthariscope, however the rate of
        beta emission is
        designed to provide useful light so individual flashes probably cannot be
        discerned.

        The rate of radioactive emission is customarily given in curies where one
        curie is equivalent to
        3.7 x 10 E10 disintegrations per second. A typical smoke detector Am241
        source contains less
        than 1 microcurie. A tritium Exit sign will contain about 10 curies in
        total.
        The current SI unit, replacing the Curie, is the Bequerel which equals one
        decay per second.


        Good screens can be obtained on Ebay. There is a current listing, for
        example, Ebay # 350317967950.

        I assume you already have a microscope: Fasten the screen (ZnS coating
        down) on the stage and set the
        alpha source (facing up) on the substage condenser so the source-to-screen
        distance can be changed.

        Enjoy

        Randall
      • Nic
        You don t want to be handling materials like Radium or Americium without proper facilities. They are both a dangerous to you but will also trigger security
        Message 3 of 19 , Jul 4, 2010
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          You don't want to be handling materials like Radium or Americium without proper facilities. They are both a dangerous to you but will also trigger 'security' interests from elsewhere waybeyond what some microscope people have seen with just chemical buying. The experiment however is fun and your best way is to probably buy an old slide on ebay ( go figure), most go for quite allot however I missed one at UK pounds 1.04 the other day :(. I think they are labelled something like Radiolara / Radiolari back when...It is a demo I would love to do with school kids but are unable to nowdays.
        • Howard Lynk
          Hello, Just so no one will spend their hard earned resources on an old antique slide, expecting a light show... Radiolarians (also radiolaria) are amoeboid
          Message 4 of 19 , Jul 4, 2010
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            Hello,

            Just so no one will spend their hard earned resources on an old antique
            slide, expecting a light show...

            Radiolarians (also radiolaria) are amoeboid <outbind://2/wiki/Amoeboid>
            protozoa <outbind://2/wiki/Protozoa> that produce intricate mineral
            <outbind://2/wiki/Mineral> skeletons <outbind://2/wiki/Skeleton> ,
            typically with a central capsule dividing the cell
            <outbind://2/wiki/Cell_(biology)> into inner and outer portions, called
            endoplasm <outbind://2/wiki/Endoplasm> and ectoplasm
            <outbind://2/wiki/Ectoplasm> . They are found aszooplankton
            <outbind://2/wiki/Zooplankton> throughout the ocean, and their skeletal
            remains cover large portions of the ocean bottom as radiolarian
            <outbind://2/wiki/Radiolarian_ooze> ooze. Due to their rapid turn-over of
            species, they represent an important diagnostic fossil
            <outbind://2/wiki/Fossil> found from theCambrian
            <outbind://2/wiki/Cambrian> onwards. The main class
            <outbind://2/wiki/Class_(biology)> of radiolarians are the Polycystinea
            <outbind://2/wiki/Polycystine> , which produce siliceous
            <outbind://2/wiki/Silica> skeletons. These include the majority of fossils.
            They also include the Acantharea <outbind://2/wiki/Acantharea> , which
            produce skeletons of strontium <outbind://2/wiki/Strontium_sulfate>
            sulfate.

            One frequently sees antique microscope slides of Radiolaria (strews,
            individual species, and arranged) offered on eBay. While these are lovely,
            they are nothing like the rarely seen slides that are actually miniature
            spinthariscopes. Occasionly one of these (a number of makers produced them
            in the early 20th c) does show up on ebay too, but every one I have seen has
            been clearly labeled as such, with "view in dark", etc. usually on the
            labels as well. These are indeed sought after, and always sell for high
            prices.

            >>>>>>>>>
            Nic said...
            (snip) ... The experiment however is fun and your best way is to probably
            buy an old slide on ebay ( go figure), most go for quite allot however I
            missed one at UK pounds 1.04 the other day :(. I think they are labelled
            something like Radiolara / Radiolari back when...It is a demo I would love
            to do with school kids but are unable to nowdays.
            >>>>>>>>>



            [Non-text portions of this message have been removed]
          • lightsurfer2
            Sorry about the junked up previous message. I tried just copy and paste of a Wiki definition of Radiolaria... unfortunately it looks like their internal
            Message 5 of 19 , Jul 4, 2010
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              Sorry about the "junked up" previous message. I tried just "copy and paste" of a Wiki' definition of Radiolaria... unfortunately it looks like their internal source and definition links pasted right along with the text.

              Howard
            • Nic
              But the main point remains people should not be preparing their own radioactive samples, buy something that has been made way back and take pot luck or buy a
              Message 6 of 19 , Jul 4, 2010
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                But the main point remains people should not be preparing their own radioactive samples, buy something that has been made way back and take pot luck or buy a professionally made demo like Dons link which looks smack on.
              • WilliamM
                All, Who was the initiator of this thread? I would like to put my 2 cents in. If the tube has no optics, I believe that it is incomplete. Secondly, what is
                Message 7 of 19 , Jul 4, 2010
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                  All,

                  Who was the initiator of this thread? I would like to put my 2 cents in. If the tube has no optics, I believe that it is incomplete. Secondly, what is the diameter of the tube? It may be possible to acquire some plano convex lenses and reconstruct it. From my recollection, there are two lenses and a ground glass filter. I would be willing to pursue this further if the original poster would like to reply to me.

                  Bill

                  --- In Microscope@yahoogroups.com, "spiutah" <spiutah@...> wrote:
                  >
                  > I already have an adaptor which has no optics in it. I was under the impression that I had bought an incomplete item. Are you saying that for use with a Standard 16 only the empty tube with its connector to the lamp housing is required?
                  > ------------
                  > That adapter should be fine on the smaller base stands...if you find it does not fully illuminate the 100x (1.3 oil) you will find my memory has failed me again, and my knowledge base has collapsed along with my occipital lobe...and my information and help is not worth 2-cents ! If you do win the bid on the ebay item you can always offer it up once again. It bothers me to see all these large research stands broken down into smaller and smaller sub assemblies and offered up to increase the return value to the seller. But alas, that might also be my only way to recover what i have spent over the years on my 'kit'.
                  >
                • Dushan Grujich
                  ... Good Day, I was reading the current thread and I remembered that I actually have an old Spinthariscope of German make which was used in schools as demo
                  Message 8 of 19 , Jul 4, 2010
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                    On 4/07/2010 2:17 PM, Nic wrote:
                    > /But the main point remains people should not be preparing their own radioactive samples, buy something that has been made way back and take pot luck or buy a professionally made demo like Dons link which looks smack on./
                    >
                    Good Day,

                    I was reading the current thread and I remembered that I actually have
                    an old Spinthariscope of German make which was used in schools as demo
                    device. I have uploaded scanned images of the documentation leaflet
                    accompanying the unit and an image of the unit itself. Leaflet is in
                    German, English and French.

                    http://groups.yahoo.com/group/Microscope/photos/album/1003146341/pic/list?mode=tn&order=ordinal&start=1&dir=asc
                    <http://groups.yahoo.com/group/Microscope/photos/album/1003146341/pic/list?mode=tn&order=ordinal&start=1&dir=asc>

                    It was made using lead 210 isotope with half life of 22 years and
                    activity of 0.5 uCi, by now long decayed as it was made in 1967,
                    although there still is some activity left to be seen.

                    Cheers

                    Dushan




                    [Non-text portions of this message have been removed]
                  • DonH
                    ... I bought one of those, so I can vouch for the vendor and the product. While I encourage experimentation with the microscope, if you are simply trying to
                    Message 9 of 19 , Jul 4, 2010
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                      > But the main point remains people should not be preparing
                      > their own radioactive samples, buy something that has been
                      > made way back and take pot luck or buy a professionally made
                      > demo like Dons link which looks smack on.


                      I bought one of those, so I can vouch for the vendor and the product. While I encourage experimentation with the microscope, if you are simply trying to observe the effect, the most practical and safe solution may be a commercial spinthariscope.

                      I have no affiliation with this vendor except as a satisfied customer.

                      Good luck,
                      Don
                    • stevenhorii
                      As a radiologist, our training included discussions of many of the various radiation incidents and errors over the years. Radium is taken up by bone as a
                      Message 10 of 19 , Jul 5, 2010
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                        As a radiologist, our training included discussions of many of the various radiation incidents and errors over the years. Radium is taken up by bone as a calcium analog. So is strontium, hence the great concern over the levels of strontium 90 in milk and agricultural products as a result of nuclear weapons tests.

                        One danger of old radioactive paint is that it can still be highly radioactive, but not glow. The radiation from the radium would degrade the phosphor in the paint, so the glow would diminish over time. Just because an old clock, watch, or aircraft instrument does not have markings that glow in the dark does not mean the item is not painted with radium-based paint. I keep a scintillation counter around since I buy surplus aircraft stuff and I check equipment I buy. Thorium, also radioactive, was used as an alloying agent in magnesium and found its way into many aerospace applications (including parts of the Apollo spacecraft). Not all surplus items get identified as posing a radiation risk before they are accessed.

                        I believe that the microscopes and stereomicroscopes used in hot rooms are disposed of as radioactive waste, but you never know.

                        Steve

                        --- In Microscope@yahoogroups.com, "Nic" <nic.rhodes@...> wrote:
                        >
                        >
                        > But the main point remains people should not be preparing their own radioactive samples, buy something that has been made way back and take pot luck or buy a professionally made demo like Dons link which looks smack on.
                        >
                      • J FLETCHER
                        My sincere thanks to all those who replied to my questions. I definitely don t want to try to prepare anything myself with radium paint, old wristwatch hands,
                        Message 11 of 19 , Jul 5, 2010
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                          My sincere thanks to all those who replied to my questions.

                          I definitely don't want to try to prepare anything myself with radium paint, old wristwatch hands, etc. I'll look for a supplier of spinthariscopes in the UK. I suspect that posting them between continents causes all sorts of problems.

                          I'm surprised that the tritium light didn't show individual flashes. Could it be because beta particles are much less massive than alpha, so each impact causes a far smaller flash of light?

                          Best regards,

                          John
                        • J. Forster
                          FYI on Thorium in gas mantles: http://en.wikipedia.org/wiki/Gas_mantle -John
                          Message 12 of 19 , Jul 5, 2010
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                            FYI on Thorium in gas mantles:

                            http://en.wikipedia.org/wiki/Gas_mantle

                            -John

                            =============


                            > As a radiologist, our training included discussions of many of the various
                            > radiation incidents and errors over the years. Radium is taken up by bone
                            > as a calcium analog. So is strontium, hence the great concern over the
                            > levels of strontium 90 in milk and agricultural products as a result of
                            > nuclear weapons tests.
                            >
                            > One danger of old radioactive paint is that it can still be highly
                            > radioactive, but not glow. The radiation from the radium would degrade
                            > the phosphor in the paint, so the glow would diminish over time. Just
                            > because an old clock, watch, or aircraft instrument does not have markings
                            > that glow in the dark does not mean the item is not painted with
                            > radium-based paint. I keep a scintillation counter around since I buy
                            > surplus aircraft stuff and I check equipment I buy. Thorium, also
                            > radioactive, was used as an alloying agent in magnesium and found its way
                            > into many aerospace applications (including parts of the Apollo
                            > spacecraft). Not all surplus items get identified as posing a radiation
                            > risk before they are accessed.
                            >
                            > I believe that the microscopes and stereomicroscopes used in hot rooms are
                            > disposed of as radioactive waste, but you never know.
                            >
                            > Steve
                            >
                            > --- In Microscope@yahoogroups.com, "Nic" <nic.rhodes@...> wrote:
                            >>
                            >>
                            >> But the main point remains people should not be preparing their own
                            >> radioactive samples, buy something that has been made way back and take
                            >> pot luck or buy a professionally made demo like Dons link which looks
                            >> smack on.
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