The Mining and mineral processing industry is important to the Canadian economy and in 2001 contributed $35.1 billion, or 3.7 percent, to the Gross Domestic Product and employed approximately 376,000 Canadians (Minerals and Metals Sector, Natural Resources Canada). However, over the past decade, Canada’s base metal reserves have declined by more than 25 percent, and significant new discoveries will be required if Canada’s role as a major base metal producer is to be maintained into the twenty-first century. The Bathurst Mining Camp is one of Canada’s most important base metal mining districts, accounting in 2001 for 30 percent of Canada’s production of Zn, 53 percent of Pb, and 17 percent of Ag. In 1999, the Bathurst Mining Camp accounted for 32 percent of the Zn, 80 percent of the Pb, and 25 percent of the Ag reserves (Minerals and Metals Sector, Natural Resources Canada). The value of production from the Bathurst Mining Camp in 2001 exceeded $500 million and accounted for 70 percent of total mineral production in New Brunswick. Approximately 2,000 people are directly employed by the mining industry in the Bathurst Mining Camp. Without the discovery of new ore reserves, however, production will decline and will cease within about 10 yr at current production rates, and with it the principal source of economic activity in northeastern New Brunswick will also disappear.To address the major decline of mineral resources in Canada’s economically important mining districts, EXTECH (Exploration and Technology) projects were established by the Geological Survey of Canada. EXTECH-II is a multidisciplinary, integrated and collaborative project that has focused on the Bathurst Mining Camp with four principal objectives: (1) update and expand the geoscience knowledge base, (2) develop and test new and improved methods of exploring for massive sulfide deposits, (3) conduct ground and airborne, geophysical and geochemical surveys to identify new exploration targets, and (4) build a multiparameter, comprehensive, coregistered, and internally consistent digital geoscience database of the entire Camp. Although EXTECH-II was initiated by the Geological Survey of Canada in 1994, it was a collaborative project involving earth scientists from the Geological Survey of Canada, the Department of Natural Resources and Energy of New Brunswick, universities, and mining and exploration companies.A similar multidisciplinary project was established at about the same time by the U.S. Geological Survey to study the well-preserved Bald Mountain Cu-Zn-Ag-Au massive sulfide deposit in northern Maine. This project, which began in 1995 and ended in 1999, also included selected research on the Mount Chase Zn-Pb-Cu-Ag-Au deposit 70 km to the south of Bald Mountain.

A prediction model, based on the differences between the distribution functions of geophysical survey data from mineralised and non-mineralised areas, has been developed to identify exploration targets. Exploration for mineral resources is conducted in a step-by-step approach, and the proposed prediction model is applicable to each of these steps. Empirical probabilities of discovering new deposits are estimated by a cross-validation technique. The cross-validation technique is central to the proposed methodology.The first study area, located in north-east Guinea, West Africa, covers 46000 km2. Magnetic and radiometric data from a 1 km line spacing airborne survey were used to create a mineral prediction map for lateritic-type gold deposits. This can be considered a reconnaissance study to identify further exploration areas likely to contain undiscovered deposits. These areas should be small enough to carry out further geologic study. From the prediction model, we have identified target areas, covering approximately 2300 km2 or 5% of the study area. We expect that the target areas contain 55% of all undiscovered lateritic gold deposits in the study region. The best prediction results are obtained when the total magnetic field, potassium abundance and uranium to thorium ratio data are used.The second example is from the Bathurst Mining Camp in New Brunswick, eastern Canada. Geophysical data are from a high-resolution helicopter-borne magnetic, electromagnetic and radiometric survey flown during the summer of 1995. This prediction study can be considered as a second step after a first reconnaissance study. The area covers approximately 4100 km2 and many volcanogenic massive sulphide (VMS) deposits are found in this region. The best prediction results are obtained using magnetic and electromagnetic data only, without radiometric data. The target areas delineated in the prediction map cover 41 km2 or 1% of the study area. From the cross-validation analysis these target areas are expected to contain 40% of all undiscovered VMS deposits in the Bathurst Mining Camp.

A multi-parameter helicopter-borne magnetic, electromagnetic (HEM) and radiometric survey completed in 1995 covered the entire Bathurst Mining Camp in Eastern Canada. The five frequency multi-coil HEM system used for this survey covers a wide frequency range and allows detailed conductivity mapping of the ground. In particular the apparent conductivity map generated from the 4433 Hz co-planar EM data shows good correlation with the bedrock geology. Conductive units are accurately delineated and can be used to help supplement detailed geological mapping. Moreover, the conductivity map shows excellent correlation with the calculated first vertical derivative of the total magnetic field, providing a means to distinguish between overburden and bedrock conductivity responses. Many orebodies are associated with discrete, coincident magnetic and conductivity anomalies.

The interaction of 800-MeV H ions with a thin foil produces protons, the ground state and excited states of neutral H atoms, and unstripped H 2 ions. We investigated the distributions of individual H 0 Stark states within the n53 and 4 levels produced by C and Al 2O3 foil stripping of H 2 ions. Foils of various thicknesses were placed upstream of a magnet with a linearly increasing transverse field along the beam direction producing a motional electric field strong enough to ionize H 0 states withn>3. We consider three questions: ~i! What are the populations of individual H 0 Stark states produced in the interaction of 800-MeV H 2 ions with thin C and Al2O3 foils, ~ii ! how do the relative population distributions change with foil thickness, and ~iii ! how is the population distribution produced in an Al 2O3 foil modified when the foil is placed in a magnetic field? A simple qualitative model is presented to explain the major trends. @S1050-2947 ~98!02212-4#

The interaction of 800-MeV H ions with a thin foil produces protons, the ground state and excited states of neutral H atoms, and unstripped H 2 ions. We investigated the distributions of individual H 0 Stark states within the n53 and 4 levels produced by C and Al 2O3 foil stripping of H 2 ions. Foils of various thicknesses were placed upstream of a magnet with a linearly increasing transverse field along the beam direction producing a motional electric field strong enough to ionize H 0 states withn>3. We consider three questions: ~i! What are the populations of individual H 0 Stark states produced in the interaction of 800-MeV H 2 ions with thin C and Al2O3 foils, ~ii ! how do the relative population distributions change with foil thickness, and ~iii ! how is the population distribution produced in an Al 2O3 foil modified when the foil is placed in a magnetic field? A simple qualitative model is presented to explain the major trends. @S1050-2947 ~98!02212-4#

The interaction of 800-MeV H- ions with a thin foil produces protons, the ground state and excited states of neutral H-0 atoms, and unstripped H- ions. We investigated the distributions of individual H-0 Stark states within the n=3 and 4 levels produced by C and Al2O3 foil stripping of H- ions. Foils of various thicknesses were placed upstream of a magnet with a linearly increasing transverse field along the beam direction producing a motional electric field strong enough to ionize H-0 states with n greater than or equal to 3. We consider three questions: (i) What are the populations of individual H-0 Stark states produced in the interaction of 800-MeV H- ions with thin C and Al2O3 foils, (ii) how do the relative population distributions change with foil thickness, and (iii) how is the population distribution produced in an Al2O3 foil modified when the foil is placed in a magnetic field? A simple qualitative model is presented to explain the major trends. [S1050-2947(98)02212-4].

Measurements of H- stripping and H-0 excited-state production for a wide range of foil thicknesses and experimental conditions are reported. An 800-MeV H- beam was passed through carbon or aluminum oxide foils of thicknesses ranging from 10 to 550 mu g/cm(2) and the excited states produced were analyzed by field. stripping in a special magnet downstream of the foil. The foil thicknesses were independently determined. The H-0 atoms emerging in excited states with n>2 can be stripped to protons in fields of up to 1.3 T The yield of excited states as a function of foil thickness and the cross sections for the various interactions are presented. The cross-section ratio of double to single ionization of H- in carbon is found to be (1.8+/-0.9)%.

Experiments were conducted to determine the effects on the distribution of H{sup o} Stark states produced in the interaction of an 800 MeV H{sup {minus}} ion beam with a thin Al{sub 2}O{sub 3} foil in a 0.16 T magnetic field. The foil was upstream of a second magnet with a constant field gradient along the beam direction resulting in a motional electric field strong enough to ionize H{sup o} states if n {ge} 3. The individual Stark states stripped at different field strengths and the remaining protons were dispersed in the field. The transverse distribution of protons was determined 5.5 m downstream using a scanning scintillator. The distributions of individual Stark states within the n = 3 and 4 levels were measured for the field-on and field-off cases. The authors observed significant differences between the field-on and field-off spectra. Compared with a statistical distribution, a greater fraction of the distribution arises from states with m = 0, and a smaller contribution is from states with m {ne} 0. This departure from a statistical distribution was present even when the foil was not placed in a field, and was further enhanced when the foil was placed in the field. In lieumore » of a quantitative theory, a simple qualitative model is presented to explain the major trends.« less

The lifetime of 800-MeV H- ions against electron detachment in a static electric field was measured over a range of eight orders of magnitude in experiments at the High Resolution Atomic Beam Facility of the Los Alamos Meson Physics Facility. The ions traversed a linear gradient magnetic field of 1.3-T peak strength resulting in a 6-MV/cm peak rest-frame electric field capable of stripping a large fraction of H- ions. The unstripped H- ions, neutral H-0 atoms, and protons were detected 5.5 m from the magnet. This spectrum was analyzed to determine the lifetime of the H- ion versus electric-field strength and the results were compared with previous studies. Three parametrizations of the lifetime formula based on an existing theory were used to calculate the stripping probability. The data were fit to the lifetime formula and good agreement with theoretical predictions was found. Finally, a possible experiment for observing excited states of H- is briefly discussed.

Foil stripping of H{sup {minus}} directly to H{sup +} is being considered for proton injection in the next generation of high-current proton storage rings. This technique can result in significant losses because excited states of HO, which are also produced in the foil, are field stripped in the downstream bending magnets. Without due care in the injection system design, many of the resulting protons will be outside the acceptance of the storage ring and will be quickly lost. We measured the production of such H{sup 0} excited states at the LAMPF High Resolution Atomic Beam Facility. An 800-MeV H{sup {minus}} beam was passed through carbon foils of thicknesses 70, 100, 200, and 300 {mu}g/cm{sup 2}, and the excited states were analyzed by a special magnet downstream of the foil. The magnet had a linear field gradient so that the trajectories of the outgoing protons could be used to reconstruct the field values at which the various H{sup 0} stripped. We found that about 1% of the H{sup 0} emerge in excited states which can be stripped to protons by ring-bending magnets.

Foil stripping of H- directly to H+ is being considered for proton injection in the next generation of high-current proton storage rings. This technique can result in significant losses because excited states of H0, which are also produced in the foil, are field stripped in the downstream bending magnets. Without due care in the injection system design, many of the resulting protons will be outside the acceptance of the storage ring and will be quickly lost. We measured the production of such H0 excited states at the LAMPF High Resolution Atomic Beam Facility. An 800-MeV H- beam was passed through carbon foils of thicknesses 70, 100, 200, and 300 μg/cm2 and the excited states were analyzed by a special magnet downstream of the foil. The magnet had a linear field gradient so that the trajectories of the outgoing protons could be used to reconstruct the field values at which the various H0 stripped. We found that about 1% of the H0 emerge in excited states which can be stripped to protons by ring-bending magnets