**Seed Project to Search for**

**Tombs in Mesoamerican Pyramids**

Edmundo Garcia (Principal Investigator)

Russell Betts, Clive Halliwell, David Hofman

Physics Department

***Summary***

Our understanding of the history of the people of Mesoamerica has
increased greatly in the past two decades. One of the more important
contributions to our knowledge has been the information gained from
tombs constructed inside pyramids. In this document we propose a method
using a proven technique for searching for tombs inside the Mesoamerican
pyramids.

The technique is based on measuring the absorption of cosmic-rays in the
material of which the pyramid is constructed, that is, limestone. This
was the method employed by Nobel Laureate, Luis Alvarez to search for
chambers inside Egyptian pyramids.

The research and development of detection systems used in high-energy
nuclear physics constitutes a core of the authors' interest. However,
the application of this effort to an area outside of the conventional
high-energy physics experiments is new for us. The environmental
conditions required for the detection system are far from the controlled
conditions of the typical experimental hall. This will be also the first
time that we will be working with a truly interdisciplinary team. In
addition, we will be investigating new techniques to store the data we
acquire from our apparatus. The concise objective of this project, its
outreach and interdisciplinary nature, makes it unique and significant.

We plan to submit a proposal to external agencies, such as the National
Geographic Society or Smithsonian Institution, immediately after the
successful completion of the seed project. The success of the seed
project based on support from the CRB will obviously be fundamental to
the overall project in securing all types of external funding.

We feel that this project will contribute to UIC's national standing and
the inter-disciplinary nature of the project will open up new
opportunities within UIC and the Chicago area. We have no doubt that
many interested parties outside of the Physics Department will be
enthusiastic in aiding us in our efforts.

**Project Description**

**Table of Contents**

[Objectives and Hypotheses. 2](#objectives-and-hypotheses.)

[Background and Rationale 3](#background-and-rationale)

[Methods 4](#methods)

[Apparatus 4](#apparatus)

[Personnel 5](#personnel)

[Time Line 5](#time-line)

[Future Plans 6](#future-plans)

[Construction of Apparatus 6](#construction-of-apparatus)

[Cost 6](#cost)

[Funding 7](#funding)

[Summary 7](#summary)

[References 12](#references)

##### List of Figures

[Figure 1: Locations of tombs at some of the major Mesoamerican sites.
8](#__RefHeading___Toc3701524)

[Figure 2: Principle of the method 8](#__RefHeading___Toc3701525)

[Figure 3: Proof of principle behind the proposed experiment.
9](#__RefHeading___Toc3701526)

[Figure 4: Principle of our seed project apparatus.
9](#__RefHeading___Toc3701527)

[Figure 5: Principle of the readout of a multi-anode photomultiplier
tube. 9](#__RefHeading___Toc3701528)

[Figure 6: Schematic diagram of the data acquisition system used to
collect and store data from our apparatus.
10](#__RefHeading___Toc3701529)

[Figure 7: Principle of reconstructing a location on the trajectory of a
muon. 10](#__RefHeading___Toc3701530)

[Figure 8: Diagrams showing the need for a \"tracker\".
10](#__RefHeading___Toc3701531)

[Figure 9: Side view of the configuration of scintillator planes.
11](#__RefHeading___Toc3701532)

## Objectives and Hypotheses.

In recent years rapid advances have been achieved in our knowledge of
Mesoamerican culture. Many disciplines have contributed to this effort
including traditional archeological studies, sociological studies, and
the deciphering of hieroglyphs. In this document we propose to
contribute to the archeological effort by searching for hidden tombs
inside Mesoamerican pyramids. Specifically, we wish to take advantage of
the absorption of cosmic rays (or "muons[^1]") in limestone, the
material of which the pyramids are constructed. This technique is not
new; it was employed successfully for the first time in Egypt more than
30 years ago in 1969 by Nobel Laureate Luis Alvarez[^2] at the Second
Pyramid of Giza. The equipment used by Alvarez was bulky (it occupied a
volume of 80 m^3^) and delicate (the detector was primarily a collection
of "spark" chambers). Since that time technological advances have made
the technique much more practical and we believe we will be able to
construct a small durable, reusable apparatus at modest cost that can be
employed over a period of time at several pyramid sites. The size of the
apparatus is crucial to the project as it will probably be necessary to
place it in a confined space such as a tunnel. We plan to have an
experiment that has a volume no more than 1 m^3^.

Tombs hold a special place in archeology and their discovery creates
headline news. Major finds in recent years include tombs in the Pyramid
of the Moon at Teotihuacan (1999), at Copan[^3] (1997), at Calakmul[^4]
(1999) and at Tikal (1999). These tombs were discovered using
traditional techniques, which are to some degree, intrusive.

It is preferable to carry out searches for tombs without disturbing the
structure that surrounds them. Recently (in 1999) a tomb was discovered
in one of the main temples at Palenque using non-intrusive ground
penetrating radar (GPR). Computer advances have made this technique a
practical way for discovering cavities. However , GPR has a serious
drawback. If the cavities are small they can only be detected a few
meters below the surface. To penetrate to greater depths longer
wavelength electromagnetic waves have to be used and this causes a loss
in resolution rendering the method impractical for detecting small tombs
deep inside pyramids. Consequently, GPR has been most successful in the
discovery of shallow graves, typically 1 to 2 m below the surface[^5]
(as was the case at Palenque). However, this is not the typical
situation at Mesoamerican sites. Many tombs are at ground level with the
pyramid having been constructed over them (as in the case of the Temple
of the Inscriptions at Palenque, see Figure 1(a)) causing the tomb to be
"invisible" to GPR. Sometimes a tomb is deep inside the pyramid because
it was originally constructed on the top of an (now enclosed) earlier
structure (for example, at Copan, see Figure 1(c)). Again, such a tomb
would not be detected using current GPR techniques. However, it is quite
likely that its presence could be determined using absorption of muons.

The authors of this proposal have already held informal discussions with
officials of the Instituto Nacional de Antropologia e Historia (INAH) in
Mexico. This government organization has identified sites where they
believe that there is a good probability of tombs of major importance
being located. We wish to aid them in the discovery of these tombs. The
authors have the expertise to carry out such an investigation using the
muon technique mentioned above. The benefit to UIC would be significant
exposure on the national scale given the great interest in the USA in
Mesoamerican culture.

## Background and Rationale

The easiest way of understanding the principle of the method we wish to
use is to imagine bullets being fired from many guns at a big pile of
sand that has an empty cavity inside it (see Figure 2). If all the
bullets were traveling at high enough velocity they would all emerge at
the other side of the sand. However, if some of the bullets are not
moving so fast, a few will be stopped by the sand. The number that are
stopped after having traversed the cavity will be less than the number
that had to traverse sand throughout. This is the basic principle of the
method we propose to use.

Instead of bullets we will use high-energy muons produced in the upper
atmosphere. Muons with a wide range of energies survive to the Earth's
surface and those that have energies greater than 15 GeV[^6] are able to
penetrate about 30 m of limestone; it is these muons that we wish to
use. We propose to place our apparatus inside a pyramid at its base so
that we are "shielded" from muons have energies less than 15 GeV[^7]. We
have carried out extensive simulations using the computer application
"GEANT"[^8] which calculates all the physical processes that muons
undergo (with the correct probabilities) when they traverse any type
material, in our case, limestone. The results are displayed in Figure
3(a) where we show that there is a significant difference in the flux of
15 GeV muons that emerge from traversing 30 m of solid limestone
compared to those that have traveled through 25 m of limestone and 5 m
of air-filled cavity. This difference decreases for higher energy muons
(see Figure 3(b) and Figure 3(c)) because a larger fraction of them
hasve enough energy to survive 30 m of limestone. If the flux of muons
arriving at the Earth's surface were independent of the muon energy, the
technique that we are proposing here would need further refinement. We
would need for example, to extend the capability of our detectors in
order to measure the muon energy. However, the muon energy spectrum at
the Earth's surface is strongly dependent on energy with the flux
decreasing by approximately a factor of 2 for every 5 GeV increase in
energy[^9]. So, as the probability of a muon of penetrating limestone
(cavity or not) increases (due to its higher energy) its flux decreases.
This fact was critical in Alvarez's successful scan of the pyramid in
Egypt. It meant that the massive equipment (such as several tons of
iron) that he used, was actually not needed to eliminate the
"background" signal from higher energy muons[^10].

Our method depends critically on the flux of muons because an experiment
spanning many years is impractical. This flux is well knownError:
Reference source not found. For vertically incident muons with energies
greater than 15 GeV, the value is 3 per second per square meter per
steradian. The apparatus that we plan to finally construct will have an
angular acceptance of about 5×10^-4^ steradians and, therefore, it would
have an acceptance of 15×10^-4^ muons per square meter per second.
Figure 3 is the result of assuming 1000 muons every square meter and
consequently would be equivalent to 10 days of data collection. This
estimate assumes vertically incident muons. In most cases the apparatus
would not be vertically below the tomb in the pyramid; it would be
displaced horizontally forcing us to make use of incident muons entering
the pyramid at an angle of, say, 45^o^. The flux of muons with energies
greater than 15 GeV decreases substantially with angle and we predict
that, more realistically, Figure 3 represents about one month of data
collection. This estimate is consistent with the actual data rate that
occurred in the experiment carried out by Alvarez.

## Methods

In this section we describe the studies and measurements that need to be
carried out in the seed project before embarking on the fabrication of
the final detector to be placed within a pyramid. We already possess
much of the equipment needed for this part of the project because one of
our future mainstream research topics[^11] is based on a similar
technique.

### Apparatus

In order to detect the presence of a muon we will use material
consisting of scintillating plastic. This material produces small
amounts of light when any electrically charged subatomic particle
travels through it. The light travels through the transparent
scintillator and is transported to a photosensitive device via an
optical fiber. The light emerging from the fiber has to be amplified
before it can be converted into an electrical pulse. This can be done
using several different techniques. We propose initially to use
photomultipliers (with which we are familiar) but we will also
investigate the possibility of using image intensifiers with a
charge-coupled device (CCD). Regardless of the specific technique we
finally employ, the result is the presence of an electrical pulse that
is stored in electronic equipment and then read into a computer for
analysis.

The apparatus for the final project will need to be of the largest area
possible but the size is constrained by the location where the apparatus
will be placed. Typically, tunnels within pyramids are about 2 m high
and 1 m wide. We plan to construct a final detector that is 0.75 m by
0.75 m in area. This detector will consist of "planes" constructed of
individual "slats" of scintillator 0.75 m long with a cross-section of 1
cm by 1 cm. The slats have to be at least 1 cm thick otherwise too
little light will be created during the traversal of a muon. Therefore,
we propose for the seed project to construct two mini-"planes"
consisting of four 0.75 m by 1 cm by 1 cm slats.

Muons will be traversing our scintillator slats continuously and it is
necessary for us to establish, independently of our slats, the presence
of a traversing muon. This is done by demanding a pair of in-time pulses
from a pair of "trigger" counters[^12] between which the slats under
study are sandwiched (see Figure 4).

We will couple optical fibers to the face of a multi-anode
photomultiplier tube (which we have on-hand). This device allows 256
separate optical fibers to be attached to it[^13]. Light will be
present, typically, on only one of these fibers. The device determines
which fiber has light by converting the light into *two* electrical
pulses that are transmitted down appropriate wires inside a pair of
16-wire cables (see Figure 5). These two signals are then stored in
registers in a "VME" electronics readout crate. This information, which
uniquely determines the identity of the slat through which the muon
passed, is then transmitted to an external computer using VxWorks, a
software application designed specifically for this task (see Figure 6).

We will measure the dependence of the amount of light generated on the
location of the traversing muon to see if the detectors have sufficient
efficiency to carry out the experiment.

In summary, the main goals of the seed project are:

-   Measurement of the amount of light emerging from our optical fibers.
    This information is critical because it will determine whether we
    use photomultipliers or a CCD in the final experiment.

-   Testing the viability of using a CCD in this type of experiment. We
    will study the potential problems of using a device that has a
    relatively slow readout time (compared to photomultipliers)

-   Construction of the data acquisition system. We will use the same
    system for the seed project and the final project.

-   Gaining familiarity with the simulation package, "GEANT", as applied
    to the specific structure we are considering.

### Personnel

The four investigators on this proposal are all researchers in the field
of high-energy heavy-ion physics. We are all members of the "PHOBOS"
experiment, a collaboration of sixty physicists studying the possible
formation of the Quark-Gluon Plasma at Brookhaven National Laboratory in
Long Island, New York[^14]. We have the necessary skills to design and
construct the equipment needed for this project (in fact, the equipment
described in this proposal is far less sophisticated than the apparatus
we have already constructed for PHOBOS). We will use the Physics
Department's machine shop to fabricate the light-couplers and the
structure to hold the scintillators in place.

It will be apparent from our current activity in our research field that
we are unable to commit 100 % of our research time to the seed project.
We will need extra support in the form of 2 undergraduate students (or
equivalent) during summer 2002 and a research assistant during part of
the 2002-2003 academic year. We request support from the CRB for funding
these students. One of us (C.H.) will be on sabbatical during the fall
2002 semester and will spend a significant fraction of his time on this
project. We believe that a team of this size is sufficient to bring the
seed project to a successful conclusion within a one year time frame.

### Time Line

We plan to construct the apparatus for the seed project over the Summer
2003 and use photomultiplier tubes to determine its feasibility to
detect muons. Later (Fall 2002) we will investigate the possibility of
using image intensifiers coupled to a charge-coupled device (CCD) to
store the data. If this part of the project is successful we will test
the apparatus in a Chicago location. We will measure the flux of muons
surviving 30 m of limestone. To do this we will investigate the
possibility of transporting the apparatus from UIC to, for example, a
limestone quarry in the vicinity.

If all this is successful we will write a proposal to fund the
construction of the apparatus for the full experiment. This will take
about a year to design, construct and test. At the completion of this
phase we plan to move the apparatus to the appropriate site in Mexico
for testing and data collection.

## Future Plans

The aim of the seed project is to establish the validity of detecting
muons using the equipment we have described in this proposal. The seed
project is absolutely necessary before we embark on the full project
described below. We discuss in this section, in some detail, the final,
overall project so that the seed project may be put into context.

### Construction of Apparatus

With the successful completion of the seed project by summer 2003 we
plan to apply for funding to construct a full apparatus that will be
capable of detecting muons and reconstructing their trajectories
unambiguously. In order to do this we will need to construct "planes" of
scintillator slats oriented parallel to each other with each slat
optically isolated from each other[^15]. When two such planes are placed
with their slats perpendicular to one another, and in close proximity
(see Figure 7), the position of the location at which the muon traverses
the planes can be reconstructed. Occasionally more than one muon will
traverse our apparatus within the time that it is sensitive to
detection. In these cases, ambiguities arise and an additional plane is
needed to resolve this.

A muon trajectory is a straight line in three dimensions and, therefore,
3 three-dimensional space points are required to unambiguously define
it. Consequently we will need to construct 3×3 = 9 scintillator planes
to reconstruct trajectories of muon. It is necessary to construct the
trajectories rather than just the presence of a muon (the latter would
require at maximum only 3 planes) because muons do not arrive at the
earth's surface in a convenient parallel beam; they have a range of
angles. By measuring their direction we will be able to choose muons
that have traversed the region where we suspect a tomb to exist (see
Figure 8).

The data collection ability of an experiment such as the one described
here increases with the size of the apparatus. Obviously there are
physical and fiscal constraints. Our defining constraint is the size of
the tunnel or cavity in which we are allowed place our apparatus.
Several Mesoamerican pyramids already have tunnels constructed by
archeologists. As we have stated, these are typically 1 to 2 m
vertically and somewhat less horizontally. Therefore, for ease of
handling we plan to construct a detector with 0.75 m by 0.75 m
scintillator planes separated by about 1 meter (see Figure 9). The
planes have to be separated by this amount so that we have the angular
accuracy necessary for detecting a tomb. Three slats 1 cm wide separated
by 1 m can measure, at most, a cavity 10 cm wide. Therefore, a tomb 2 m
wide should be easily discernible[^16].

### Cost

The cost of the hardware for the full-scale detector will be in region
of \$100,000. The scintillator alone will cost \$50,000. In order to
collect enough data to make a definitive statement about a tomb within a
pyramid we estimate that data must be taken at the site for about 6
months. We will design the support structure for the equipment so that a
minimal amount of supervision by physicists will be necessary (we
anticipate that we will probably need only one person-year of qualified
personnel at the site).

### Funding

We anticipate applying for internal funding from UIC's Campus Research
Board for a Type II project in 2003. By that time we will have made
contacts with faculty in UIC's Department of Anthropology and would have
formed a multi-disciplinary faculty team. We will also apply for funding
from external sources such as the National Geographic Society and the
Smithsonian Institution. There is already interest in this project from
INAH, in Mexico, and we anticipate a certain level of support from this
organization. Finally, we will investigate the possibility of support
from the Hispanic community within the Chicago area.

## Summary

We propose in this document to carry out a seed project that would lead
to the construction of a compact, robust piece of equipment that can be
used to detect hidden tombs in Mesoamerican pyramids. The proposed
method is a significant improvement on one used in Egypt more than 30
years ago.

The authors of this proposal have the interest and technical expertise
to carry out this project to its final conclusion. We already work in a
social environment that requires us to work together and we anticipate
no problems in integrating experts from different disciplines onto the
project.

We believe that this project will be an excellent base for
cross-disciplinary studies, which could provide a degree at the MS level
within UIC's Department of Physics and, maybe, a degree at the PhD level
in UIC's Department of Anthropology. At the appropriate time we will
start discussions with faculty in that department. In addition, there
may be an opportunity to collaborate with interested parties based at
the Field Museum in Chicago. We feel that we have a unique opportunity
to bring together diverse disciplines and cultures in a project that has
widespread interest within our society.

+----------------------------+-----------------------------------------+
| ![](media/image1.png){w    | ![](media/image2.png){width="3.91875in" |
| idth="2.551388888888889in" | height="2.13125in"}                     |
| hei                        |                                         |
| ght="4.247916666666667in"} | ![](media/image3.png){width="3.45625in" |
|                            | height="2.076388888888889in"}           |
+----------------------------+-----------------------------------------+
| []{                        |                                         |
| #__RefHeading___Toc3701524 |                                         |
| .anchor}Figure 1:          |                                         |
| Locations of tombs at some |                                         |
| of the major Mesoamerican  |                                         |
| sites[^17].                |                                         |
|                            |                                         |
| > \(a\) Palenque, where    |                                         |
| > the tomb is at ground    |                                         |
| > level.                   |                                         |
| >                          |                                         |
| > \(b\) Tikal., where      |                                         |
| > several tombs at this    |                                         |
| > site are above ground    |                                         |
| > level.                   |                                         |
| >                          |                                         |
| > \(c\) Copan, where a     |                                         |
| > location of a tomb is    |                                         |
| > above ground level.      |                                         |
+----------------------------+-----------------------------------------+
| ![](media/image4.jpeg){wi  |                                         |
| dth="3.7930555555555556in" |                                         |
| heig                       |                                         |
| ht="2.8645833333333335in"} |                                         |
|                            |                                         |
| []{                        |                                         |
| #__RefHeading___Toc3701525 |                                         |
| .anchor}Figure 2:          |                                         |
| Principle of the method    |                                         |
+----------------------------+-----------------------------------------+

![](media/image5.png){width="4.25625in" height="3.548611111111111in"}

[]{#__RefHeading___Toc3701526 .anchor}Figure 3: Proof of principle
behind the proposed experiment.

> These four false-color pictures show the intensity of muons that
> survive traversing a limestone structure 30 m high and with a 10 m by
> 10 m cross-section area. The structure had a cube of side length 5 m
> placed centrally inside it. Red color denotes many muons, blue denotes
> few, white denotes none. We simulated muons to be vertically incident
> on the top face of the limestone and we allowed them to have different
> energies: (a) 15 GeV, (b) 20 GeV and (c) 25 GeV.
>
> We can see from (a) that only muons that have traversed the cavity
> survive to the bottom of the limestone structure. The effect of the
> cavity is still apparent with 20 GeV muons. Finally the effect becomes
> undetectable when 25 GeV muons are studied. The cumulative effect,
> with the correct energy dependence of the muon spectrum included, is
> shown in (d). The presence of the cavity is clearly apparent.

+---------------------------------+------------------------------------+
| ![](media/image6.pn             | ![](media/image7                   |
| g){width="2.1458333333333335in" | .png){width="2.4916666666666667in" |
| height="2.43125in"}             | height="2.5305555555555554in"}     |
|                                 |                                    |
| []{#__RefHeading___Toc3701527   | []{#__RefHeading___Toc3701528      |
| .anchor}Figure 4: Principle of  | .anchor}Figure 5: Principle of the |
| our seed project apparatus.     | readout of a multi-anode           |
|                                 | photomultiplier tube.              |
+---------------------------------+------------------------------------+

![](media/image8.png){width="3.3833333333333333in"
height="1.917361111111111in"}

[]{#__RefHeading___Toc3701529 .anchor}Figure 6: Schematic diagram of the
data acquisition system used to collect and store data from our
apparatus.

![](media/image9.png){width="2.5034722222222223in" height="2.95625in"}

[]{#__RefHeading___Toc3701530 .anchor}Figure 7: Principle of
reconstructing a location on the trajectory of a muon.

![](media/image10.png){width="5.427083333333333in"
height="2.0868055555555554in"}

[]{#__RefHeading___Toc3701531 .anchor}Figure 8: Diagrams showing the
need for a \"tracker\".

> \(a\) Trajectories of muons traversing our apparatus regardless of
> their direction.
>
> \(b\) Trajectories of muons that are required to be detected in our
> apparatus *and* to have trajectories within a defined angular range.

![](media/image11.png){width="2.8319444444444444in" height="4.075in"}

[]{#__RefHeading___Toc3701532 .anchor}Figure 9: Side view of the
configuration of scintillator planes.

> In the final setup a total of nine planes will be needed to
> unambiguously define the trajectory of each muon traversing our
> apparatus. We show here the effect of extrapolating a measured
> trajectory from a muon that has scattered in the limestone. We also
> show, in the magnified insert, the effect of the width of each slat on
> reconstructing a trajectory. The reconstructed trajectory necessarily
> has to assume that the trajectory went through the center of the slat.

## References

[^1]: The majority of cosmic-rays that reach the Earth's surface consist
    of muons, a subatomic particle similar to an electron but 200 times
    heavier.

[^2]: L. Alvarez et al., Science, New Series, Volume 167, 3919 (1970)

[^3]: The Hunal Tomb is believed to contain the burial of Copán\'s
    dynastic Founder, K\'inich Yax K\'uk\' Mo\'. A website that has
    extensive details of this discovery can be found at
    <http://www.famsi.org/reports/sharer3/sharer3pg7.htm>.

[^4]: "New Evidence on Yukom Yich\'ak K\'ak\', a Ruler from Calakmul",
    R. G. Vargas et al., Jour. Latin American Antiquity, 10 (1999)

[^5]: Discovery of military tombs is described at
    <http://www.du.edu/~lconyer/fort_vancouver.htm>

[^6]: The unit "GeV" is a unit of energy where "G" refers to "giga",
    that is, a multiplicative factor of 10^9^, and eV is an electron
    unit.

[^7]: It may be possible to carry out our experiment by placing our
    apparatus external to a pyramid. However, we feel this need not
    decided upon at the present time.

[^8]: The authors are all familiar with this application as it is the
    primary simulation tool that is used in high-energy physics to
    design experiments. We used it to design components of PHOBOS, the
    experiment we are all currently engaged in at Brookhaven National
    Laboratory. GEANT was developed at CERN, the European High Energy
    Laboratory.

[^9]: The measurement of the intensity of high energy muons has been
    published by:

    > M. P. der Pascale et al., J. Geophys. 98, (1993)
    >
    > O. C. Allkofer et al., Phys. Lett. B36 (1971)
    >
    > B. C. Bastin, J. Phys. G10, (1984)
    >
    > C. A. Ayre et al., J. Phys. G1, (1975)

    J. Kremer et al., Phys. Rev. Lett. 83 (1999)

    and has been parametrized in Europhysical Journal C, p 151 (2000).
    The flux of 15 GeV muons is given by the equation:

    $$\frac{\text{dN}}{\text{dE}_{\mu}} = \frac{0\text{.}\text{09}}{E_{\mu}^{2\text{.}7}}\frac{\frac{\frac{\frac{\ }{\text{cm}^{2}}}{s}}{\text{sr}}}{\text{GeV}}$$

[^10]: In fact, Luis Alvarez included a muon absorber, made of iron, to
    estimate the energy of the muons detected in his apparatus. In ref.
    Error: Reference source not foundError: Reference source not found
    he describes how he did not need to use this absorber at all in his
    experiment.

[^11]: We are planning to construct a "calorimeter" for the CMS
    experiment which plans to take data at the CERN accelerator in 2007.
    The calorimeter will measure the energy created by the showering of
    neutrons emerging from a high-energy collisions of nuclei.

[^12]: These trigger counters are also constructed of scintillator
    material but much larger in volume. We have a few of such counters
    already in our laboratory and we will devote a pair of them to this
    project.

[^13]: In our final apparatus we will have 9 planes each of 75 slats
    totaling 675 slats. The readout of these will require 3 multi-anode
    photo-multiplier tubes if we choose to use this method.

[^14]: Information on the PHOBOS experiment can be obtained from the
    experiment's web site at
    [www.phobos.bnl.gov](http://www.phobos.bnl.gov/). Recent
    publications from the PHOBOS experiment are:

    > "Central Dependence of Charged Particle Multiplicity at \|η\|\<1
    > in Au+Au Collisions at 130 and 200 GeV", submitted to Phys. Rev.
    > C, (2002)
    >
    > "Central Dependence of Charged Particle Multiplicity at \|η\|\<1
    > in Au+Au Collisions at 130 GeV",
    >
    > Phys. Rev. C, (2001)
    >
    > "Energy dependence of particle multiplicities near mid-rapidity in
    > central Au+Au collisions",
    >
    > Phys. Rev. Lett. 88, (2001)
    >
    > "Ratios of charged antiparticles-to-particles near mid-rapidity in
    > Au+Au collisions at 130 GeV",
    >
    > Phys. Rev. Lett. 87, (2001)
    >
    > "Charged particle multiplicity near mid-rapidity in central Au-Au
    > collisions at 56 and 130 GeV",
    >
    > Phys. Rev. Lett. 85, (2000)

[^15]: Adjacent segments have to be optically isolated so that we light
    created by the muon is constrained to a single segment and does not
    leak into adjacent ones. Optical isolation can be achieved by
    wrapping each scintillator slat in light-tight plastic wrap or
    painting with the appropriate reflecting coating. These methods are
    commonly used in high-energy physics experiments.

[^16]: There is an additional effect that degrades our resolution to
    detect cavities. Muon trajectories within limestone are not straight
    lines because scattering occurs. We have studied this using our
    GEANT simulator. The degradation of resolution is three times worse
    than the effect caused by the width (1 cm) of our slats.

[^17]: All diagrams of tomb locations are taken from "The Maya, Divine
    Kings of the Rain Forest", edited by N, Grube. (1999)