Booster Applications Facility Instrumentation*
D. Gassner, S. Bellavia, K. A. Brown, I. H. Chiang, P. Pile, R. Prigl
Brookhaven National Laboratory, Upton, NY 11973, USA
Abstract. A new experimental facility being at built at BNL will take advantage of heavy-ion beams
from the AGS Booster for radiation effects studies of importance for the Space Program. A large
dynamic range response is necessary to accommodate a wide variety of species (protons to gold) and
energies (100 MeV/amu to 1.3 GeV/amu). The instrumentation proposed for extraction control and
transport diagnostics will include phosphor screens with video cameras, segmented wire ionization
chambers, ion chambers, and scintillators. Design and development of these systems will be presented.
INTRODUCTION
The principle source of ion beams for the US National Aeronautics and Space
Administration (NASA) accelerator-based radiobiology program is at the BNL
facility1. Since 1995, the Alternating Gradient Synchrotron (AGS) has yearly
delivered a limited set of ion species and energies for a community of approximately
70 investigators from 15-20 institutions. The focus has been on 600 and 1000 MeV
iron, 1000 MeV silicon, and 10,000 MeV gold ions. More than 1000 biological
samples were irradiated at the AGS A3 beam line, in addition to physics experiments
to establish beam characterization and dosimetry data. Operating time for
radiobiology at the AGS is at a premium, as the major running time is dedicated to
nuclear physics and high-energy physics research. The NASA program has typically
had 1 to 2 running periods of 150 hours duration during a given year. Each period
consists of continuous beam operations of 24 hours per day until all the approved
experiments for the period are completed.
TABLE 1
Operating Parameters for Slow Extraction Beam for Some Typical Ion Species.
Species
Charge
Kinetic Energy
Estimated Max
State
Range
Intensity
In Booster
(GeV/Nucleon)
(109 Ions/Pulse)
1
0.10-3.07
100
H1
28
14
0.09-1.23
4
Si
21
0.10-1.10
0.4
Fe56
Cu63
Au197
22
0.10-1.04
1
32
0.04-0.30
2
* Work performed under auspices of the U. S. Department of Energy.
CP648, Beam Instrumentation Workshop 2002: Tenth Workshop, edited by G. A. Smith and T. Russo
© 2002 American Institute of Physics 0-7354-0103-9/02/$19.00
O C'}
353
The AGS is not designed for providing high quality beams in the energy range of
highest interest to the radiobiology research community. The energy range of the AGS
Booster, which serves as injector to the AGS, provides a much better match. The
Booster Application Facility (BAF), which is scheduled for commissioning in
FY2003, will be a dedicated NASA particle beam source that will provide for all ions
from protons to gold in an energy range from 40-3000 MeV/nucleon, with beam
intensities ranging over 6 orders of magnitude. A pair of octupole magnets in the BAF
beam line will provide the flat beam profile required for most irradiations without the
need of heavy collimation.
The present NASA planning guidance is for yearly operation of 15 weeks of
weekly 5 shift operations. A sample list of available ions with relevant characteristics
is provided (Table 1). BAF will operate in slow-extracted2 mode; the spill can be
varied from the Booster uniformly over a 0.5-1 second spill every 3-6 seconds. At the
target station the beam size can be varied from 1 cm to 20 cm in diameter for 95%
beam intensity and maximum emittance.
BEAM LINE DIAGNOSTICS
A total of 7 instrumentation locations are specified for the 100 meter BAF transport
beam line. At these locations a total of 7 phosphor screens (flags), 5 Segmented Wire
lonization Chambers (SWIC's), 5 Ion Chambers (IC's) and 3 Scintillator/PMT's
(Scint's) will be installed as shown (Figure 1 and Table 2).
D6 Extraction
Septum Sa
02 Scre(
SWIC & Scint
Booster
Synchrotron
Figure 1. BAF Transport Layout
354
Final Window
Screen, SWIC,
1C & Scint
TABLE 2
BAF Instrumentation Details
Location (just
upstream of)
1) D6 Septum
2)Q1
3)D1
4)01
5) O2
Final window
6) DS window
7) Target Area
Flag
SWIC
Wire Spacing
(32/plane)
Horiz.
Vert.
Yes
Yes
Yes
Yes
Yes
N/A
6mm
1.5mm
6mm
3 mm
N/A
6mm
6mm
1.5 mm
6mm
Yes
Yes
6mm
N/A
6mm
N/A
Beam Size (90% full
width)
Horiz.
25 mm
60mm
17mm
90mm
20mm
200mm
>200mm
>200mm
Vert.
25 mm
120mm
75mm
8 mm
90mm
160mm
>160mm
>160mm
Ion
Cham.
Scint.
/PMT
No
Yes
Yes
Yes
Yes
No
Yes
No*
No*
Yes
Yes
No
Yes
No
Est.
Vacuum
(10n
Torr)
-11
-10
-9
-9
-8
-8
Air
Air
*Note: All 4 vacuum instrumentation stations are capable of a full compliment of SWIC, 1C, and
scintillator heads.
VACUUM CONSIDERATIONS
In order to comply with the request from NASA for minimal material in the beam
path from the Booster, all the diagnostics stations were designed with plunging
capabilities. There is a 6" beam pipe from the Booster to the upstream end of the BAF
transport tunnel, then increasing to 8" until the last trim magnet, and a 12" pipe for the
remainder of the line to the only transport vacuum window.
An important factor related to this requirement was compatibility with the existing
Booster vacuum system. Because it would cause unacceptable beam losses for low
momentum heavy ion beams, a vacuum window can not be used to separate the
Booster 10"11 Torr ultra high vacuum (UHV) system from the BAF beam line vacuum
system. A transition vacuum from the Booster ring vacuum to the line vacuum will be
provided. Pressures of 10~10 Torr and 10~9 Torr will be required in the first two
vacuum sections of the line respectively. The first section of the line will be bakeable
to 150°C. The rest of the line will be a clean all-metal gasket, unbaked vacuum system
with ion pumps. Since a robust UHV, bakeable instrumentation assembly had to be
designed for the first upstream section, it was decided to use this same design at the 3
other downstream locations. In order to ensure the integrity of the Booster vacuum,
the diagnostics chamber design must provide sufficient safety margin. A failure of a
vacuum window closer than 45 meters (based on fast valve response time) to the
Booster would compromise the Booster vacuum enough to cause a month delay for
baking and pumping down.
TRIPLE PURPOSE DIAGNOSTIC STATION
Each stainless steel diagnostic station vacuum enclosure has 8" beam pipe ports
and additional ports for vacuum pumps and gauges. The aluminum plunging vessel,
which travels about 10" inside the station vacuum enclosure, houses the diagnostics
355
heads,
windows machined
machined to
to aa thickness
thickness of
of10
10mils.
mils. AA
heads,and
andhas
has 8"
8” diameter
diameter aluminum
aluminum windows
mixture
of
80%
Argon
and
20%
COz
flowing
through
the
plunging
vessel
at
just
mixture of 80% Argon and 20% CO2 flowing through the plunging vessel at just
above
gas. A
14" O.D.
O.D. welded
welded bellows
bellows isisused
usedto
to
above 11atmosphere
atmosphere is
is used
used as
as the
the counting
counting gas.
A 14”
plunge
the
vessel
into
the
beam
path
as
shown
in
Figure
2.
A
bolted
flange
on
the
plunge the vessel into the beam path as shown in Figure 2. A bolted flange on the
bottom
service of
of the
the diagnostics
diagnostics heads
heads without
without
bottomof
of the
the bellows
bellows allows
allows removal
removal and
and service
disturbing
feature, 2400
2400 lbs
Ibs of
of force
force are
are
disturbingthe
thevacuum
vacuum system.
system. To
To incorporate
incorporate this
this feature,
needed
stand and
and large
large motor
motor
neededto
toretract
retract this
this large
large surface
surface area,
area, requiring
requiring aa reinforced
reinforced stand
drive.
and vertical
vertical SWIC,
SWIC, dual
dual
drive. Each
Eachvessel
vesselhas
has the
the capability
capability of
of housing
housing aa horizontal
horizontal and
ion
shown in
in Figure
Figure 3.
3. The
The SWIC’s
SWIC's will
will be
be used
used
ionchambers
chambers and
and aa scintillator
scintillator head
head as
as shown
totomeasure
intensity beams,
beams, the
the voltage
voltage bias
bias
measuretransverse
transverse beam
beam profiles.
profiles. For
For the
the lower
lower intensity
can
be
increased
for
operation
in
the
proportional
region.
The
scintillator
and
ion
can be increased for operation in the proportional
and ion
chamber
time
chamberwill
will measure
measure low
low and
and high
high intensity respectively, as well as time
characteristic
characteristic data.
data.
Figure2.
2.Plunging
Plunging instrumentation
instrumentation vacuum
vacuum assembly
Figure
assembly and
and stand.
stand. Retracted
Retracted position.
position.
TheSWIC
SWICand
and ion
ion chamber
chamber HV
HV bias
bias planes,
planes, and
and ion
ion chamber
The
chamber signal
signal planes
planes are
are
constructed of
of 11 mil
mil aluminum
aluminum foil
foil stretched
constructed
stretched over
over aa G10
G10 frame.
frame. The
TheSWIC
SWICsignal
signal
wires,from
fromLUMA
LUMAWire,
Wire, are
are O.Vmil
0.7mil gold
gold plated
plated tungsten
tungsten with
wires,
with 3%
3% rhenium.
rhenium. To
To
compensate for
forthe
the variety
variety (1.5
(1.5 to
to 6mm)
6mm) of
of SWIC
SWIC wire
wire spacing,
compensate
spacing, separated
separated HV
HV bias
bias
willbe
beused
usedfor
foreach
eachplane.
plane. The
The ion
ion chamber
chamber electrodes
electrodes are
will
are separated
separated by
by 6.4mm
6.4mm and
and
356
an
an electric
electric field
field on
on the
the order
order of
of 11 kV/cm
kV/cm will
will be
be applied.
applied. The
The thin
thin scintillator
scintillator material
material
is
the
is mounted
mounted downstream
downstream of
of the
the SWIC
SWIC and
and IC.
1C. A
A light
light guide
guide extends
extends below
below to
to the
photomultiplier
photomultiplier tube
tube and
and base,
base, which
which extends
extends below
below the
the plunging
plunging vessel.
vessel.
Figure 3.
3. Detail
Detail of
of
Figure
plunging diagnostics
diagnostics
plunging
head assembly.
assembly. Left
Left
head
shows
upstream side
shows upstream
side
with SWIC
and ion
ion
with
SWIC and
chamber signal
and bias
bias
chamber
signal and
planes. Right
Right shows
shows
planes.
downstream side,
with
downstream
side, with
scintillator,
light guide
guide
scintillator, light
and photomultiplier.
photomultiplier.
and
ELECTRONICS &
& CONTROLS
CONTROLS
ELECTRONICS
All of the diagnostic electronics (except for the flag
flag upstream of the extraction
septum) and controls will be located in the 957 service building. Signals from
from each of
the 32 wires in the horizontal and vertical plane of the SWIC will be processed by a
Eurocard chassis using eight, 8 channel Advanced Technology Laboratory model
lOOpF and 10,100pF
10,100pF capacitors for high
224900 integrator modules configured with 100pF
and low gain settings. After
After a programmed time sequence, both sets of 32 channels
are scanned and multiplexed into a serial signal path that is digitized by a VME based
14 bit multiplexed A/D
A/D converter
converter designed for RHIC. The profile data
synchronized 14
is presented graphically by a high level application; data acquisition can be configured
configured
to display a mountain range display showing the evolution of the profile over the spill.
Ion chamber electronics will consists of BNL designed current to frequency
frequency (I/F)
converters that also provide an analog output for monitoring intensity throughout the
spill. System calibration is based on calculated pair production in the counting gas,
and a precision current source for the electronics. Over all three available gain
settings, the module has > 100dB
lOOdB dynamic range. High gain mode calibration is about
7 fC/count. Recycling integrator front-end electronics are under consideration.
Standard Phillips NIM photomultiplier counting electronics that include amplifier,
discriminator, and level translator will process the scintillator/PMT signals.
357
Low
of extracted
extracted ions
ions are
are counted
counteddirectly
directlyfrom
fromthe
theplastic
plasticscintillators.
scintillators.
Low numbers
numbers of
When
saturation
occurs,
the
ion
chambers
will
be
used
to
measure
the
higher
intensity.
When saturation occurs, the ion chambers will be used to measure the higher intensity.
The
ion
chambers
and
scintillators
systems
can
be
cross
calibrated
when
the
extracted
The ion chambers and scintillators systems can be cross calibrated when the extracted
beam
is within
within the
the dynamic
dynamicrange
rangeof
ofboth
bothsystems.
systems.
beam intensity
intensity is
A
SIS
3808
VME
scalar
will
read
in
the
counts
from
theI/F
I/Fconverter
converterand
and
A SIS 3808 VME scalar will read in the counts from the
scintillator
counting
electronics;
data
can
be
displayed
various
ways
via
the
highlevel
level
scintillator counting electronics; data can be displayed various ways via the high
controls
system.
controls system.
A
4500 HV
HV Mini-System
Mini-System will
will provide
providehigh
highvoltage
voltagebias
biasfor
forall
allrelated
related
A Bira
Bira VME
VME 4500
systems.
system enables
enables full
full remote
remotecontrol
controlof
ofall
allaspects
aspectsofofthe
thebias
biaslevels
levels
systems. This
This system
including
and current
current trip
trip thresholds.
thresholds.
including voltage
voltage and
Flag
illumination
lamp
controls,
electronicsgain
gaincontrol,
control,plunging
plungingcontrols,
controls,
Flag illumination lamp controls, electronics
readbacks
of
limit
switches,
and
system
status
will
be
handled
by
VMIC
1160and
and
readbacks of limit switches, and system status will be handled by VMIC 1160
2170A
digital
input
and
output
VME
boards.
2170A digital input and output VME boards.
PHOSPHOR SCREENS
SCREENS
PHOSPHOR
To
higher resolution
resolution transverse
transverse beam
beamsize
sizeatathigher
higherintensities,
intensities,plunging
plunging
To acquire
acquire higher
phosphor screens
screens are
are used
used which
which are
are housed
housedininseparate
separatevacuum
vacuumchambers.
chambers.The
Thefirst
first
diagnostic system in the BAF
BAF transport
transport isis aascreen
screenjust
justupstream
upstreamofofthe
thethick
thickejection
ejection
septum magnet in the Booster
Booster ring.
ring. This
This stepper
steppermotor
motordriven
driven88position
positionrotating
rotating
assembly has 11 screen, 33 stripping
stripping foils,
foils, 33stripping
strippingwires
wiresfor
forlow
lowintensity
intensity
experiments, and 11 blank
blank as
as shown
shown in
inFigure
Figure4.4. During
DuringBooster
Boosterslow
slowextraction
extractionsetup
setup
and diagnostics, the Morgan Matroc
Matroc Chromox
Chromox66aluminum
aluminumoxide
oxidescreen
screenwill
willbebe
positioned in the beam path
path to
to allow
allow beam
beamposition
positionand
andsize
sizemeasurement
measurementofofthe
thebeam
beam
kicked from the upstream
upstream thin
thin septum.
septum.
Duetotohigh
highradiation
radiation
Due
levelsproduced
producedwhile
while
levels
runninghigh
highintensity
intensity
running
protonson
onnon-BAF
non-BAF
protons
cycles,aarad-hard
rad-hardDage
Dage
cycles,
70Rvideo
videocamera
camerawill
willbebe
70R
Mirror
Mirror
mounted
mountedacross
acrossthe
theaisle
aisle
Geneva drive
in
inthe
theBooster
Boostertunnel.
tunnel. ItIt
Viewing
Viewing
mechanism
will
willgather
gatherlight
lightfrom
fromthe
the
port
port
screen
screenvia
viaaaquartz
quartz
vacuum
vacuumport
portand
andmirror
mirror
mounted
above
mounted aboveassembly.
assembly.
Between
Betweenthe
thevideo
videocamera
camera
and
andlens
lensfixture
fixturewill
willbebea a66
position
positionrotating
rotatingneutral
neutral
density
densityfilter
filterassembly
assembly
that
thatwill
willeliminate
eliminate
Rotating
saturation
Rotating
saturationproblems.
problems.
Screen/foil/wire
Screen/foil/wire
holder
holder
Figure 4.
4. Screen
Figure
Screen and
and stripper
stripper assembly
assembly upstream
upstreamof
ofextraction
extractionseptum.
septum.
358
An Imaging
Imaging Technology
Technology Inc.VME based frame
An
frame grabber
grabber will
will process
process the
the analog
analog video
video
signal; aa high
high level
level application
application will
will then
then display
display the
thebeam
andcalculated
calculated
signal;
display
the
beam profiles
profiles and
and
calculated
parameters.
parameters.
Figure 5.
5. At
At left
left
Figure
plunging screen
screen
plunging
vacuum assembly
assembly with
with
vacuum
with
mirror below.
below. At
At right
mirror
right
detail of
of DC
DC motor
motor
detail
actuator, bellows
bellows and
and
actuator,
flag holder
holder tilted
tilted atat45
45
flag
45
degrees.
degrees.
There will
will be
be 55 plunging
plunging screen
screen locations
locations in
in the
the 100
100 meter
metertransfer
transfer line,
line,each
each
There
locations
in
the
100
meter
transfer
line,
each
having
a
dedicated
vacuum
chamber
assembly
which
includes
a
quartz
viewing
and
having a dedicated vacuum chamber assembly
assembly which
which includes
includes aa quartz
quartz viewing
viewing and
and
illumination port,
port, mirror,
mirror,and
andaa24VDC
24VDCmotor
motor
plunging
actuator
as
shown
in
Figure
5.
illumination
plunging
actuator
as
shown
in
Figure
motor plunging actuator as shown in Figure 5.
5.
The video
video camera
camera assembly
assembly will
willbe
bemounted
mounted
on
an
adjustable
stand
with
drawer
The
on
an
adjustable
stand
with
drawer
mounted on an adjustable stand with drawer
slides, and
and recessed
recessed inside
inside the
the camera
camera cubby
cubby as
asshown
shownin
inFigure
Figure6.
6. This
Thisassembly
assembly
slides,
cubby
as
shown
in
Figure
6.
This
assembly
includes aa CCD
CCD 1394
1394 Firewire
Fire wirevideo
videocamera,
camera,
neutral
density
filter
assembly,
lens,and
and
includes
neutral
density
filter
assembly,
camera, neutral density filter assembly, lens,
lens,
and
an image
image intensifier
intensifier in
in some
somelocations.
locations. The
The
digital
video
signal
from
these
cameras
an
digital
video
signal
from
these
cameras
The digital video signal from these cameras
will be
be processed
processed in
in building
building957
957on
onaadedicated
dedicatedpersonal
personalcomputer
computerrunning
runningframe
frame
will
dedicated
personal
computer
running
frame
grabber analysis
analysis software
software33..
grabber
Lens
Lens
filter
filter
camera
camera
Figure 6.
6. Camera
Camera cubby,
cubby, with
with CCD
CCDcamera,
camera,intensifier,
intensifier, neutral
neutraldensity
densityfilter,
filter,and
andlens
lens
Figure
Figure
6.
Camera
cubby,
with
CCD
camera,
intensifier,
neutral
density
filter,
and
lens
on
drawer
slide.
At
right,
camera
assembly
orientation
to
flag
vacuum
chamber.
on
drawer
slide.
At
right,
camera
assembly
orientation
to
flag
vacuum
chamber.
on drawer slide. At right, camera assembly orientation to flag vacuum chamber.
359
At the end of the beam line, after the final vacuum window a full compliment of
plunging devices will be installed. Though the size of the SWIC, 1C, scintillator and
flag will be large to cover the 12" beam pipe aperture, the design is less complex since
there are no vacuum issues.
SUMMARY
A total of 20 diagnostics systems will be installed in the BAF transport beam line.
All of the system transducers can be retracted during experimental running to
minimize the material in the beam path. The mechanical design provides sufficient
safety margin to ensure the integrity of the Booster vacuum. The dynamic range of
the detectors and electronics is sufficient to provide measurements over most of the
planned operating modes. For very low intensity operations, the beam line will
initially be set up at higher intensity, and then reduced and the separate experimental
target dosimetry system will be used. Commissioning is scheduled during early
FY2003.
ACKNOWLEDGMENTS
The authors would like to thank Tony Curcio, Stephen Jao, Peter Oddo, Sal
Polizzo, Joe Saetta, Al Weston, and Paul Ziminski for electronics support. We would
also like to thank Dave Kipp, Dan Lehn, Al Ravenhall, Craig Rhein, Lou Snydstrup,
Don Von Lintig for mechanical support. In addition we are indebted to Larry Hoff,
Joe Skelly, and Wes Buxton for handling the Controls aspects of this system. We
appreciate the support and advice of Tom Russo.
REFERENCES
1. Lowenstein, D. I., "BNL Accelerator-Based Radiobiology Facilities" First Intl. Workshop on Space
Radiation Research and lithe NASA Space Radiation Health Investigators' Meeting, Arona Italy,
5/2000.
2. Brown, K. A., et al., "Resonant Extraction Parameters for the AGS Booster" PAC 2001, Chicago.
3. Brown, K. A., D. Gassner, et al., "IEEE 1394 Camera Imaging System for Brookhaven's Booster
Application Facility Beam Diagnostics", EPAC 2002, Paris.
360