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INSTITUTE OF NUCLEAR SCIENCES DtpartiMnt of SdontHtc and Industrial RoMarcfi

LOWER HUTT. NEW ZEAUND

40 Institute of Nuclear Sciences IHS-R-385

NUCLEAR PHYSICS GROUP PROGRESS REPORT

July-Decenber 1981

Edited by: G.E.Coote.

December 1982

Institute of Nuclear Sciences O.S.I.R. Lower Hutt, N.Z. ABSTRACT

The work of the Nuclear Physics Group of the Institute of Nuclear Sciences during the period July-December 1981 is described.

KEYWORDS

VAN DE GRAAFF ACCELERATORS;TANDEM ELECTROSTATIC ACCELERATOR; PROTON MICROPROBE ANALYSIS;X-RAY FLUORESCENCE; RADIOACTIVE ISOTOPES;CARB0N-ll;NITR0GEN-13; NUCLEAR MAGNETIC RESONANCE; DATA PROCESSING EQUIPMENT; DATA ACQUISITION .-MICROPROCESSORS; ARCHAEOLOGICAL SPECIMENS; BONE; FLUORIDES; APATITE. Graham J. McCallum

Graham McCallum, head of the INS accelerator group since i cs inception in 1962, died on Mt. Ruapehu, New Zealand, on July 11 1981. While instructing a small group of beginners he was engulfed by a snow avalanche; the others escaped unharmed, but he could not be revived by a doctor skiing nearby. Thus ended the life of one of Mew Zealand's outstanding scientists and scientific leaders. Prominent among New Zealand mountaineers for many years, he had climbed all the country's peaks higher than 3000 meters, had taken part in expeditions to the Himalayas and the Andes, and had visited Antarctica to instruct American scientists in survival techniques. After years of achievement on high and difficult peaks it was tragic that he should be killed in an area used by skiers.

Graham joined DSIR in 1949 and continued his university studies in phvsics and mathematics during the next two years. Following his first research project on the measurement of natural radioactivity in soils he helped develop the then new technique called radiocarbon dating. The laboratory was pioneering the use of proportional counters filled with carbon dioxide and he evaluated the accuracy of the resulting dates. While the site for the planned Institute of Nuclear Sciences was being developed he was seconded to overseas laboratories to gain experience.

At Harwell (1955-59) he worked for two years with the Pile Neutron Research Group, measuring neutron cross sections of isotopes available only in minute quantity. When it seemed probable that New Zealand would purchase an accelerator he transferred to the Van de Graaff group, where he studied energy levels in isotopes of titanium and vanadium. One year later he moved to Chalk River (1959-61) just in time to become involved in the commissioning of the world's first tandem accelerator. During those exciting days he studied the theory of gamma-ray angular correlation and polarization, performed a number of such measurements, and published with A.E. Litherland a paper on the triple correlation technique. But his future work in New Zealand was not forgotten and he continued planning the building to house the 3 MV accelerator and the experimental programme he was to lead.

On his return to New Zealand in 1962, with the accelerator building still on the drawing board, he initiated experiments at a 400 kv accelerator at nearby Victoria University of Wellington. The research field (the study of short-lived nuclides produced in reactions initiated by neutrons) later paved the way for an experimental programme in which New Zealand has made major contributions: application of the short-lived isotopes A1C and 13N to the study of photosynthesis and translocation in plants, and to df.nitrification by bacteria in soil. Production of these isotopes for plant physiologists in a nearby laboratory became an important function of the 3 MV accelerator, and the most important of many interdisciplinary projects. In his last published paper six authors reviewed the application of short-lived isotopes in agricultural research in New Zealand.

The development of the Ge(Li) gamma-ray detector at Chalk River during 1963 lead to a reappraisal of the experimental programme and Graham encouraged a new staff member to stay there to learn how to make them. For some years experimental research at INS utilised homemade detectors until a better one could be purchased. He gathered around him a small team of scientists and technicians who, though interested in pure nuclear physics, were willing spend some of their time developing important applications. As well as isotope production these included the analysis of materials by X-ray fluorescence, nuclear reactions and X-rays generated by proton bombardment. Construction of a nuclear microprobe began in 1977.

Graham wrote many computer programs, and published papers on the accurate efficiency calibration of Ge(Li) detectors and the correction for effects which were important when the radioactive source was close to the detector. For some years he continued determinedly with a huge project on the sourcing of obsidian, in which 8000 samples were analysed by the XRF technique.

In June 1978 he received a letter from Sir Ernest Titterton, asking if DSIR would be interested in buying a cyclotron no longer needed in Canberra. Some years before Graham had proposed that the scope of the work with isotopes be enlarged by the purchase of a cyclotron. He might have accepted the offer, had there not been a footnote- "Or would you prefer the tandem?" Though well aware that his group was small and finance was limited, Graham did not hesitate- he obeyed his favourite injunction "We've got to take an optimistic attitude!" and opted for the tandem. Rochester and McMaster laboratories had shown that a tandem accelerator could be used for radiocarbon dating of small samples, and this proved to be an influential argument for purchase of the machine and construction of a building to house it.

Three days before Graham died the walls of the building were under construction and the last shipping container of tandem components arrived on site. Graham had regarded installation of the tandem accelerator as the climax of his career, and it was sad that he did not live to complete it.

Despite the state of shock we were in during the following week the group resolved that the best memorial to Graham and his pioneering work would be an accelerator laboratory that the country could feel pride in, operated by people who were determined to make important contributions in pure and applied science. In November 1982 the accelerator complex was dedicated and named the McCallum Laboratory.

Graham is survived by his wife Ann and their three children, all displaying excellence in their university studies.

Graeme Coote CONTENTS Page 1. SUMMARY 1

2. RESEARCH PROJECTS 2

2.1 Nuclear Techniques of Analysis 2

2.1.1 Nuclear Microprobe Applications 2

2.2 X-ray Fluorescence 3

2.2.1 Instrumentation 3

2.2.2 (X,X*) Spectrometry 3

2.3 Short-lived Isotope Studies 3

2.4 Nuclear Magnetic Resonance 4

2.5 Atmospheric Studies 4

2.5.1 Atmospheric Tritium Sampling 4

2.5.2 Atmospheric Carbon Dioxide 4

3. INSTRUMENTATION 5

3.1 6 MV Tandem Van de Graaff Accelerator 5

3.1.1 New Tandem Building 5

3.1.2 Installation of Equipment 6

3.1.3 Development of Equipment 6 3.2 3 MV Van de Graafff Accelerator 8

3.2.1 Operation 8

3.2.2 Accelerator Maintenance 8

3.2.5 Pulsed Radiolysis 8

3.3 Data Acquisition and Analysis Facilities 9

3.3.1 PDP-8 9

3.3.2 PDP-11/34 9

3.3.3 LSI-11 Systems 9

3.4 Electronics and Mechanical Development 9

3.4.1 Electronics 9

5. VISITS AND MEETINGS 10

6. PUBLICATIONS, REPORTS AND LECTURES 10 1.

1. SUMMARY

The transfer of the EN-tandem accelerator from Canberra to Lower Hutt was completed in early July, when the last two containers arrived. We estimate that the total weight transported was 130 tonnes. The construction of the building to house the accelerator, gas-handling equipment and the second experimental area progressed rapidly throughout a wet winter; the topping-of f ceremony took place on September 23 and the completed building was handed over on December 22nd. The 23-tonne tank was lifted into position by crane before the roof trusses were placed. It rested on stands made from railway sleepers and was finally lowered onto the pedestals after the building was closed in. The end carriages and ion source were moved into place before the end wall was closed in. In the meantime progress had continued with the analyzing magnet, the inflection magnet, their associated chambers and the beamlines in the main target area.

The concurrent construction project, the electron terminal for pulsed radiolysis, took a slight change of direction. We had learned of a group at Delft who had built such a terminal on a machine identical to ours, and had documented it well. During a visit to Delft by G.B. Coote they indicated their willingness to help us and have already provided valuable drawings and photographs. Our terminal will therefore be based on the Delft rather than the Argonne design.

The nuclear microprobe continued to provide valuable information on radial profiles of fluorine in excavated bone. This work, as well as that on fluorine concentrations in coexisting minerals in metamorphic rocks, was reported at the Second International Conference on Microanalysis with Charged Particle Beams, at Mamur in Belgium. An idea picked up at this conference resulted in the launching of a new project- depth profiling of sodium in obsidian. This work progressed rapidly, despite our inexperience in such applications, and already shows promise as a new dating method in archaeology.

The MMR project benefitted from the gift of a high-resolution magnet and associated equipment, which were being replaced by Chemistry Division. The electronic apparatus which came with it is being modernised.

A special event was the publication of a paper by six authors, which reviewed ten years of research work in agriculture made possible by the C and N radioisotopes produced on our accelerator. The main topics were photosynthesis, translocation of sucrose through plants, uptake of nitrate and ammonium ions by the roots of plants, and denitrification by bacteria in soil.

An agreement was reached between INS and the New Zealand Meteorological Service that the accurate measurement of C0_ levels in air from the southern oceans will become a joint project. A microcomputer has been purchased to become the basis of an automatic system which should be easier to maintain. 2.

2. RESEARCH PROJECTS

2.1 Nuclear Techniques of Analysis

2.1.1 Nuclear Microprobe Applications

(a) Fluorine profiles in archaeological bone - G.E.Coote, S. Holdaway (Univ. of Otago)

(This study was introduced in INS-R-294). Further linear scans of human finger phalanges from Taunako (Solomon Islands) were carried out to complete this project. One important fact which emerged from the companion study, on Moa bone from Hawksburn, Otago, was that bone which had been burnt in Maori cooking fires about 508 years ago had not absorbed any fluorine from the ground water - the radial distributions were flat and the concentrations remarkably low (about 0.C4%). However, there were still sharp spikes in the profiles, showing that the high temperatures had not smoothed these out. This confirms a conclusion from our early work that fluorine is held very firmly in the hydroxyapatite crystals of bone.

To learn more about the influence of the structure of a uone on the fluorine profile we performed two-dimensional scans of Moa bones which contained Haversian (longitudinal) canals. The profiles were compared with photographs from a scanning electron microscope. A B.A.(Kons.) thesis describing these two studies was written by Simon Holdaway.

(b) Depth profiling of sodium in obsidian - G.E.Coote, P. Nistor (Univ. of Otago)

Obsidian (volcanic glass) was highly regarded by early man for the making of edge tools. From the time the tool is finished the glass surfaces start to deteriorate, with the formation of a shallow "hydration rim". If the thickness of this layer can be measured it should be possible to date the tool. The extreme thinness of this layer (rarely more than a few microns) has caused many disappointments in the search for a reliable technique.

At the Namur conference on microprobe applications (September 1981) C. Engelmann of Saclay described a technique for measuring depth profiles in glass, by using the 1G12 keV resonance in the reaction "Na(p,a y)2CNe, which is readily monitored by detecting 1634 keV gamma rays with a large Nal crystal. His work is linked to the nuclear power programme in France and the storage of high-level waste.

Recent work has shown that the hydration of glass takes place in two steps: alkali metals diffuse outward, to be replaced by hydrogen (as H30+) diffusing inward. As the hydrogen and sodium profiles are complementary a measurement of either will tell us the depth of the "rim".

We decided to test this technique as a method for dating obsidian. After a few weeks the initial problems were overcome and a series of profiles had been measured on obsidian from New Zealand, Mexico and taster Island; no hydration layer was thicker th3n lym, even though some of the surfaces looked very old.

The special features of the microprobe proved useful. For example we 3.

could examine the effects of focussing the beam, and could scan the beam to see whether the profile shape varied across the specimen. With further work we hope to develop this technique into a valuable tool for the archaeologists.

2.2 X-ray Fluorescence

2.2.1 Instrumentation — G. Wallace

The molecular sieve of the Canberra Industries Si (Li) detector required replacing, otherwise little trouble was experienced.

2.2.2 (X, X*) Spectrometry

(a) Bromine Estimations - D. Hannah (Chem Div.), J. Grey (IPD), G. Wallace

Several batches of foodstuffs were routinely analyzed for bromine prior to their release for sale in N.Z. This work is temporarily in abeyance due to some argument over the relevant regulations.

Assistance in the development of a pilot process for Br fumigation of export apples has continued, with several hundred samples checked for residual concentrations. The upper limit is 5 ppm (wet weight). Several apple samples were found to have high lead concentrations - the orchards concerned were to be investigated.

(b) Motorway Bolts - G. Wallace, G. Page (IPD).

Ministry of Works had supplied several galvanised iron guardrail bolts with the aim of establishing corrosion criteria for fasteners in contact with copper- chromium-arsenate treated timber. The bolts had been in service for up to 10 years, and exhibited varying amounts of corrosion. Residual zinc coating thicknesses ranged from 0 to 26 mg/cm^. in certain cases arsenic and copper from the treated timber were also present in the coating. Heads of some of the bolts showed lead deposits from car exhaust emissions.

(c) Chemical Processing - G. Wallace

Various samples were run for the Radioscope Section to check chemical methods.

2.3 Short-lived Isotope Studies n 11 Experiments on plants using C and N continued during this period, but the serious illness of J.D. Stout meant that there was no further work on denitrification of soils.

An important event was the publication of a paper which reviewed ten years of agricultural research in New Zealand, based on 1:1C and ^ radioisotopes produced by our accelerator. 4.

2.4 Nuclear Magnetic Resonance - L.A. McLachlan

Data can now be transferred from the signal averager using a Fortran subroutine based on the SAINT subroutine of G. Wallace, suitably modified to cope with the unorthodox data format used in the serial transfer output.

Apart from building a permanent sample cooling system, this completed the work needed to restore the spectrometer to use. Following the laws of probability governing scientific research, a high resolution magnet and its associated equipment immediately became available from Chemistry Division. Accordingly the 9" Magnion electromagnet and its power supply were replaced by a 12" Varian V4013A electromagnet. This shifting was carried out by a highly capable and motivated local gang of moving agents, suitably bribed.

This old American-designed equipment used valve amplifiers and runs off 110 volts. During installation it is being upgraded to run off 230 volts and to use transistors and integrated circuits wherever possible. To date the Varian V3507A field sweep, the Varian V4365A field homogeneity control and the Varian V3506 magnet flux stabiliser have been so modified. It is somewhat surprising that even the best transistor or integrated circuit DC low noise amplifier does not have as good a performance as an old-fashioned moving-coil galvanometer with a light-beam pointer so this part of the flux stabiliser circuit was retained. Galvanometers are, unfortunately, both mechanically and electrically very fragile. To prevent electrical damage, a circuit was added which shorts out the galvanor.ieter input by means of a reed relay as soon as the deflection exceeds a preset limit. Such a procedure should protect the galvanometer but it has the disadvantage of increasing the galvanometer time constant from three seconds to about 10 minutes. This poses operational difficulties so clearly more thought needs to be given to this problem.

2.5 Atmospheric Studies - K.P. Pohl

2.5.1 Atmospheric Tritium Sampling

Routine operations continued.

2.5.2 Atmospheric Carbon Dioxide

(a) Data' analysis - P. Pohl and M. Manning

This work is proceeding satisfactorily, with considerable effort being expended to ensure that results are presented with their associated errors correctly accounted for.

(b) Equipment

In an effort to make the analyzer more reliable and easier to maintain, an order for a large quantity of spares was placed with the local agent. When these parts arrived they did not fit (except for one); the reason for this is that, even though the instrument was delivered in 1976, we still do not have complete documentation. 5.

Toward the end of the period a sudden change occurred in the characteristics of the analyzer: the sensitivity continually increased. No definitive cause was found but during disassembly for other reasons small drops or the oil used to lubricate the shutter motor were found on the cell windows; after these were removed the drift decreased somewhat. It is presumed that the increase in sensitivity was due to the evaporation of the droplets.

Diurnal drifts have been a continuing problem with this project. Contributing factors found previously were the temperature sensitivity of the analyzer itself (solved by enclosing it in a constant temperature enclosure) and the warming of a pressure regulator by afternoon sunlight (solved by blocking a window).

Another source of drift was recently identified: leaks in the gas tubing which enabled ambient carbon dioxide levels to affect the readings. This obvious possibility had been ignored because the system had been found "leak-free" during reconstruction two years ago. The standard "soap-bubble" leak test was not adequate - each joint had to be enclosed in an atmosphere of carbon dioxjde and remade until no response was found in the output. The exact mechanism is unclear as the system operates at a slight positive pressure above atmospheric.

Replacement data-logging and control equipment has been ordered in conjunction with the New Zealand Meteorological Service. This will comprise a DEC LSI-11/2 microcomputer with cassette tape storage medium. Special emphasis is being placed on the long-term maintainability of the system.

The traditional Christmas failure occurred punctually on December 22. The cooling compressor failed, requiring installation of the spare on the 23rd December.

3. INSTRUMENTATION

3.1 6 MV Tondem Van de Graaff Accelerator

3.1.1 New Tandem Building - R.D. More

Excellent progress was made on the building and the "Topping Off" function was held on 23rd September. With the building weather proof some major components were brought out of storage and placed in the building. A gantry crane was installed in the tandem hall. After the major components had been installed in the tandem hall, the end wall of the building was completed. This had been left to allow easy access to the building. The floors of the old and new buildings were brought to the same level; this required some concrete cutting and relaying a section of the old floor.

The official inspection and handing over of the building took place on 22nd December 1981. 6.

3.1.2 Installation of Equipment - R.D. More, CM. Bartle, R.J. Sparks, G. Wallace, C. Purcell, F. Pike, J. Kindred

The accelerator tubes for the tandem were visually checked and found satisfactory, and then stored in a safe area. Trench supports were designed and manufactured. A decision was made to lift the tank into the building before the roof was constructed. Temporary supports for the tank were constructed from wooden railway sleepers. In August the tank was lifted with a large crane, maneouvered between some already erected wall panels, and lowered onto the supports in the tandem hall.

A magnet jig for the P52 magnet was constructed to allow the top half of the magnet to be lifted by jacks. The top half (3 tonnes) was lifted, using the jig, to insert the new magnet chamber.

When the roof was finished the major components of the . accelerator were taken out of storage in Bell Road and brought into the new building. This involved extensive use of cranes and trucks. Once inside the new building these heavy objects were moved with skates and manpower. The first component to be placed was the high energy end carriage, followed by the water chiller, tank pedestals and the P36 magnet.

The pedestal bases were cleaned and the mounting bolts checked. The pedestals themselves were cleaned and greased and moved into position. The four inside pedestals were erected first. The outside pedestals were erected and used to raise and position the tank, while the weight was finally taken on the inner pedestals. The temporary supports (railway sleepers) were removed so that we again had access to the trench.

The low energy end carriage was brought into the tandem hall from storage, placed on the rails and pushed into its approximate position. The ion source which was stored in the existing experimental area was moved out of the building and into the tandem hall. Both the H.E. and L.E. carriages were adjusted for height and lateral position.

A start was made on installing trench supports and laying of trunking for electric cables.

3.1.3 Development of Equipment

(a) Sputter Ion Source - G. Wallace

The source is being fabricated at Auckland University. Most power supplies or components have now been received, and the assembly of these and the control system should start shortly.

(b) P15 Inflection Magnet - G. Wallace, L. Wyatt, A. Jalil

The stand for this was completed and the magnet mounted. The magnet has been tested to 5EA coil current and appears satisfactory; however, a degaussing power supply has yet to be devised. The main chamber has been fabricated but insulating flanges and extensions are still under construction.

A twin-headed cryogenic pump system has been received, and an 7.

associated roughing pump assembled for the adjacent beam lines.

(c) P52 Analyzing Magnet - G. Wallace, CM. Bar tie, R.J. Sparks

The new chamber and expansion box was inserted, and extended through to the switching magnet. It has been vacuum tested. Both the analyzing and switching magnets have been wired and successfully tested. The NMR system on the P52 analyzing magnet was installed and tested. The Hall probe on the switching magnet works, and is being duplicated as we seem to have insufficient to monitor all the magnets. The degauss supplies for the analyzing and switching magnets seem to be faulty.

(d) Duopiasmatron Ion Source - CM. Bar tie, R.J. Sparks, C.R. Purcell

The duopiasmatron ion source which has operated satisfactorily for IP and D~ beams has been dismantled and positioned at the lower energy end of the Van de Graaf f accelerator. The plasma bottle and the electrode structure were withdrawn from the source and cleaned. In particular the insulators between the electrode elements were removed and cleaned in an acid solution.

With a view to ultimately producing a lithium beam from the ion source a mechanical device has been constructed which will allow the plug, which prevents lithium escaping from the lithium oven, to be removed when the lithium supply is to be replenished. Instructions have been obtained from ANU on the handling of lithium and the means of loading the oven.

The ion source will be reassembled once the electrical and water supplies are reconnected to the source in its present position.

(e) Beam Lines - CM. Bartle

The beam tubing now positioned in the P52 magnet has been connected through to lines 2 and 3. This required particular beamline lengths to be chosen to enable the exit slits, positioned downstream from the magnet, to be located at the required distance of 2R(R = particle trajectory radius in the magnetic field) from the field exit. A 2" diffusion pump has been installed near the exit of the magnet. When the magnet chamber was pumped down using this pump a vacuum of 8 x 10~° torr was obtained confirming that the magnet chamber is probably leak-free. Leak-chasing tests using the ANAVAC residual gas analyzer will be required to confirm this. Viton "O-rings" have been used in the beamlines located in the magnet room. Presently tests are underway to improve the quality of the vacuum throughout the composite vacuum system from the P52 magnet through to the beamlines 2 and 3. Those tests will be hindered until improvements are made to the Varian pump on line 3. At present pumping with the 2" diffusion pump mentioned earlier and the 4" diffusion punp on line 2 produces a pressure of approximately 5 x 10""5 torr.

Planning for the beam line between the P52 magnet and the P36 magnet includes the possible installation of the Varian pump presently located on line 1.

(f) Vacuum Pumps - CM. Bartle, G. Wallace, P. Pike 8.

The titanium sheet required to renew the cathodes in the two Varian pumps has been obtained. The bending work is to be done by PEL and the milling by the INS workshop. When the pumps are complete, probably by March, one will be used on line 3 (carbon dating line) and the other, presently on line 1, is to provide pumping between the P52 and P36 magnets. The two cryopumps to be used in conjunction with the sputter ion source have arrived from Airproducts Inc.

3.2 3 MV Van de Graaff Accelerator

3.2.1 Operation - C.R. Purcell, R. D. More

During this period the accelerator was run for 315 hours.

Breakdown of usage was as follows - Hours Machine Days

INS Nuclear Physics Group Protons 158.7 20 INS Isotope App. Section Protons 78.9 13 PEL Biophysics Section lie Deuterons 30.7 35 PEL Biophysics Section 13N Deuterons 46.4 19

Total 314.7 87

3.2.2 Accelerator Maintenance - C.R. Purcell, R.D. More

The gate valve control unit was investigated and a burnt out "Vacuum fail" relay was replaced. A short circuit had caused the master remote cable to burn out. The replacement cable has been rewired so that it is protected by fuses.

The generating voltmeter (G.V.M.) motor bearings became noisy. The gas was released from the tank and the assembly replaced. The original has been repaired and is now the spare.

The up-charge power supply developed a fault, which was traced to a faulty rectifier tube in the 60 kV power supply; this was replaced. A few weeks later the supply started breaking down. We found that an anode cap was not making good contact.

A water connector failed on the 3 MV magnet chamber flooding part of the magnet room. The spray of water caused a burnout of the solenoid controlling the beam stop. This failure was a result of blockages in the cooling circuit caused by aluminium corrosion in the bottom viewer under the magnet and in the focus ring above the magnet.

3.2.5 Pulsed Radiolysis - CM. Bartle, J.G. West

There has been a change in the philosophy underlying the development of the pulsed radiolysis system. Following a visit by Dr.G.E. Coote to Delft in the Netherlands where a pulsed radiolysis system is operated at the Intoruniversitair Reactor Instituut we will base our design on their system rather than the Argonne System for the following reasons -

(a) The design is similar to the Argonne system which we were previously 9.

studying; (b) The details of the system are better documented in the literature than the Argonne system; (c) The staff at the IRI have pledged their support during our development work. We have received circuit drawings and mechanical details.

3.3 Data Acquisition and Analysis Facilities

3.3.1 PDP-8 - J.G. West

Total hours to date - 26,438. Hours run during half year - 44.

Recently, not much use has been made of the PDP-8 system. Where possible, jobs such as the control of the proton microprobe now employ an LSI-11 system.

Corruption of data stored in the disk system occurred a couple of times and this necessitated the reloading of the disks.

3.3-2 PDP-11/34

The PDP-11/34 processor, some peripherals and terminals are now covered under a DEC service contract. So far, one call-out has been made to service an LA36 printer. Service work done by INS included a faulty RP11 disk, the Anelex line printer, a CAMAC interface and the Tektronix 4025 graphics terminal.

A 5kVA mains supply isolating transformer has been installed and the PDP-11/34 racks are now connected onto the "clean earth" system.

3.3.3 LSI-11 Systems - J.G. West

A cut-sheet feeder was installed onto the Diablo printer at the work station and apart from some initial problems nas given satisfactory performance.

3.4 Electronics and Mechanical Development

3.4.1 Electronics - Computer Air Conditioning Plant - J.G. West

Investigations are still being undertaken by MOWD into this plant and in general it is agreed that some re-commissioning work should be undertaken. So far several sections of MCWD have been involved but as yet no work has been approved.

3.4.2 Miscellaneous Electronic Servicing - J.G. West, I.B. Guild

The following equipment required repairs or modifications: CAMAC ADC interface, LSI-11 ADC multiplexer, Analex line printer, CI 8040 ADC, ND130 multichannel analyzer, PDP-11 disk, Quad 100V Bias supply, Air Conditioning plant, Tektronix 4025 terminal, DSIK network links, Ortec 439 current digitizer, H19 terminal, Kicksort coincidence pulse generator. 10.

5. VISITS AND MEETINGS

G.E. Coote had been advised early in the year of a grant which would enable him to make a visit to Europe, to spend about three weeks visiting laboratories with microprobes as well as those which have embarked on ultra-sensitive mass spectrometry with accelerators or are preparing to do so. By good fortune he received news of a conference on microprobes at Namur, Belgium, just in time to submit a paper. Following the valuable 3-day conference in September he visited 16 laboratories before returning home. These were : Laboratories with microprobes: University of Amsterdam; ETH, Zurich; Max Planck Institute, Heidelberg; University of Oxford; University of Namur; Nuclear Physics Section, Harwell; Tandem Accelerator Laboratories : University of Utrecht; CEA., Bruyeres Le Chatel; CRNS, Strasbourg; ETH, Zurich; University of Oxford; Kellog Radiation Laboratory, Caltech; Other Laboratories :CEA, Saclay; Interimiversitair Reactor Instituut, Delft (Pulsed radiolysis); Radiation Centre, Birmingham; Archaeological Laboratory, Oxford; British Museum (Natural History).

This trip resulted in the forging of a number of valuable contacts and friendships, and has already lead to one successful new project. It is expected that contacts made at the British Museum will lead to some valuable joint projects.

6. PUBLICATIONS, REPORTS AND LECTURES

Nuclear Physics Group Progress Report, Jan-June 1981. Edited by G.E. Coote. Institute of Nuclear Sciences INS-R-294.

Applications of short-lived Isotopes in Agricultural Research in New Zealand. G.J. McCallum, G.S. McNaughton, P.E.h. Minchin, R. More, M.R. Presland, and J.D. Stout. Nuclear Science Applications 1 (1981) 163-190.

A battery driven High Power Pulsed NMR Power Amplifier using Commercial Broad-band Transistor Amplifier Modules. L.A.McLachlan, Jnl. of Magnetic Resonance, Vol. 47, 490, 1982.

Nuclear Microprobe Measurement of Fluorine Concentration Profiles, with application in archaeology and geology. G.E. Coote, R.J. Sparks and P. Blattner. Mucl. Instr. Meth. 197 (1982) 213-221. Presented at the Second International Conference on Microanalysis, Namur, September 1981.

Experimental measurements for the following thesis were carried out on the INS 3 MV accelerator: Fluorine profiling: A new method for relative dating of bone. Simon Koldaway, B.A.(Hons.) Thesis, Anthropology Department, Otago University, 1981.