As announced in the last HRIBF Newsletter
proposals to be submitted to the Program Advisory Committee
must be received on or before December 13, 2001.
Detailed instructions including important dates may be found on our
website. A list of
including expected intensities is also available.
Some web-based programs may also be beneficial to your planning:
major experimental endstations and on
may be found in previous HRIBF Newsletters. The
membership of PAC-7 is also available.
We encourage you to contact us with
suggestions for the beams you require to pursue your physics research.
as to what constitutes a suitable beam for the HRIBF
may be found in our more recent newsletters.
We ask that you need to be aware that scheduling experiments at our
facility is difficult. In some cases such as transfer experiments, suitable
equipment is not yet in place to take full advantage of the allocated
beam time. In other cases, sufficiently many experiments must be available
before it is "cost effective" to schedule a particular RIB ion source
or endstation configuration.
Additional information reflecting the present status of equipment and
techniques is provided below.
- Information from Previous PACs
- Neutron-rich RIB Development - Isobarically pure Sn beams
We are investigating the possibility of increasing yields of our pure
Sn beams. Following up on our
that SnS+ beams can be extracted from our source with no SbS or TeS
components, work done at
that the addition of H2S gas or
CS2 vapors may increase the SnS yields.
Based on the sulphur current output from the source, a factor of 3
improvement in intensity may be possible.
- CARDS - Clover Array for Recoil Decay Spectroscopy
CARDS was installed at the RMS focal plane in September. Consisting
of four Clover Ge detectors in a cross (X) geometry with an optional
fifth detector (Clover or Gamma-X) on the beam axis, a highly
efficient detection system for recoil decay products is possible.
For example, our measured photopeak efficiency was approximately
18% at 80 keV, 8% at 500 keV, and 4% at 1333 keV.
Pictures of the set-up, including the newly installed MCP (see below) are
In September, a 7 us isomer has been discovered in
140Dy. CARDS will be coupled with
the Moving Tape Collector (MTC) in December for a series of beta decay
experiments. CARDS equipment, except the Clovers, has been provided
by Louisiana State University. In this experiment, more than 20 pnA
of 315 MeV 54Fe was used.
- Microchannel plates at final focus of the RMS
New vacuum chambers have been installed at the final focus of the Recoil
Mass Spectrometer which can house
systems (MCP). Three experiments have been performed to date.
In addition to the 140Dy
the decay of 96mAg was studied
using CARDS and the RMS in diverging mass mode (only 1.5 masses on
the 6 cm foil). Fine structure in proton emission from
141gsHo has been discovered using the
double-sided silicon strip detector (DSSD) with XIA electronics and the
RMS is converging mass mode. Here, the MCP was not at the mass focus
but much closer to the 4 cm square DSSD. The gas avalanche counter
PSAC determined the mass position at the focus and the placement of
collimators. The PSAC was then removed. A report on these experiments
will be available in the Winter 2002 newsletter.
A larger MCP detector has been purchased and we expect all hardware
to be in-house before the PAC meeting. This detector can replace the
PSAC in converging mode and we hope will be available toward the
end of the period.
- Forward Array
Elements of the annular forward array will be tested in February. Several
of the double-sided detectors are in-house; each detector consists of
16 annular strips and 8 radial strips which result in 128 pixels.
The full array will consist of 12 wedges in two layers creating a large
pixellated dE-E telescope array. The CAEN ADCs and TDCs have been
incorporated into our data acquisition programs and await testing.
The prototype of the shaper has been tested and returned to the
vendor for minor modifications. The constant fraction model is in
the design stage; initial tests will be performed using in-house
level discriminators. It is hoped that a single layer of the full
detector will be available to experiments toward the end of period.
- (d,p) reactions using the RMS
The astrophysics group's silicon detector array SIDAR was installed
at the RMS in July and used to measure the
reaction. The RMS selected 5 MeV/u fully stripped
19O products and delivered them to a
silicon strip detector. This test, with the addition of the
MCPs with removable foils, should allow full kinematic reconstruction
of light radioactive ion (d,p) reactions. Extension to higher mass RIBs
will require improved performance of the electrostatic components of the RMS
and/or energy degradation of the products. Such studies will benefit
from the completion of the forward array (see above).