dr. CRISTINA BORDEANU's web page

Sample menu:

• Home
• Contact
• CV
• Publication list
• Conferences
• Seminars abroad
• Colaborations/Projects
• Ph.D. Thesis
• Slide presentations

• Quick links
• Contact me

2000-2002 – Weizmann Institute of Science (download PDF)

---

2000 –2002 2 ½ years on a postdoctoral position won through an international competition at Weizmann Institute of Science WIS Rehovot, Israel, “The Edmond I. & Lillian S. Kaufman Postdoctoral Fellowship”.

I collaborated with Professor Michael Hass (lab CEO) and with Professor Michael Paul (from the Racah Institute of Physics, Hebrew University, Jerusalem) for:

• - a)Pelletron 14MV, on multiple problems de Accelerator Mass Spectrometry:

• o -Towards a measurement of the cross section for ³He(⁴He,γ)⁷Be with Accelerator Mass Spectroscopy (AMS),
• o -Experimental limit to interstellar ²⁴⁴Pu abundance,
• o -Be-10 measurements on Neolithic and Paleolithic flint tools from Israel,
• o -An insight into Pu-244 abundance in interstellar matter,
• o -Counting Ti-44 nuclei from the Ca-40(α,γ)Ti-44 reaction,
• o -A window on nucleosynthesis through detection of short-lived radionuclides,
• o -Flint mining in prehistory recorded by in situ-produced cosmogenic Be-10,
• o -Magnet saturation and relativistic effects in accelerator-mass-spectrometry systems,
• o -Upgrading of the AMS facility at the Koffler 14UD Pelletron accelerator

Many such publications came out of this period of time (see the publication list).



• - b)at the 3MV Van de Graaff accelerator, on 3 issues for Nuclear Astrophysics


• o b1) astrophysical factor measurement S₁₇(0) for the nuclear reaction ⁷Be(p,γ)⁸B responsible for the most energetic neutrinos coming from our Sun:

• § -A new measurement of the proton capture rate on ⁷Be and the S₁₇(0) factor,
• § -Precision measurement of the ⁷Be(p,γ)⁸B cross section with an implanted ⁷Be target,
• § -A new measurement of the proton capture rate on Be-7, New measurement of the proton capture rate on Be-7 and the S-17(0) factor



• o b2) astrophysical factor measurement S₃₄(0) for the nuclear reaction ³He(⁴He,γ)⁷Be responsible for the ⁷Be neutrinos, with the goal of normalizing all other previous results for this astrophysical factor:

• § -Towards a measurement of the cross section for ³He(⁴He,γ)⁷Be with Accelerator Mass Spectroscopy (AMS),
• § -Next steps on the cross section measurement for the fusion reaction ⁴He(³He,γ)⁷Be.



I did the design and the commissioning of the reaction gas-chamber, used to study the nuclear reaction ⁴He(³He,γ)⁷Be, and I established the experimental method for this measurement. In the end of my position there, I could test the chamber while running a preliminary experiment ⁴He(³He,γ)⁷Be at the 3MV accelerator.




I learned to perform AMS (Accelerated Mass Spectrometry) measurements in Professor Michael Paul’s group, from Racah Institute of Physics from Hebrew University, Jerusalem. Here is what I did:

- Chemical separation method of the ⁷Be nuclei from the implantation metal Cu (the method was a result of a collaboration with chemist Chana Feldstein from the Racah Institute of Physics, Hebrew University, Jerusalem)

- Method to obtain standard probes for the AMS for the ⁷Be nuclei (method resulted from collaboration with Professor Michael Paul)

- Data analysis for the ⁷Be counting through the AMS method.



• o b3) study the nuclear reactions which may destroy ⁷Be si ⁷Li in our Sun

• § I participated at Yale University, Connecticut, USA, to an USA-Israeli-Belgian cooperation experiment for Nuclear Astrophysics (spoke-person Professor Moshe Gai):

• § -Destruction of Li-7 and Be-7 in astrophysical environments.



• c) At ISOLDE, CERN, Geneva, I participated to a nuclear magnetic moment measurement (spoke-person Professor Michael Hass):

• § Magnetic moment of Ne-17 using beta-NMR and tilted foil polarization

Activity results from this period were presented at renowned schools, such as:

• § Erice school: the 22^nd School on Radioactive beams in Nuclear and Astro Physics (2000), Sicily, Italy,
• § Santa Tecla, Sicily, Italy : The 1st European Summer School on Astrophysics (2001),
• § TRIUMF, Vancouver BC, Canada (2002) : SNIT 2002, Summer Nuclear Institute at TRIUMF 2002, June 10-21, 2002

and at international conferences, as:

- AMS (see the publication list)

§ -Carbon-dating (2000) (see the publication list)

§ -Nuclear Astrophysics (see the publication list).

When I worked at WIS, for the AMS, I accomplished:

• - Carrying out the method of AMS detection of the ⁷Be nuclei (and perfecting it), which allow counting the atoms created in the reaction ³He +⁴ He (see list of publications).
• - I worked in chemistry labs from WIS and from the Hebrew University to determine the chemistry to be used for the preparation of ⁷Be probes for AMS.
• - I participated in the completion of the computerized control of the 14MV Pelletron AMS, using LabVIEW, and to its technical implementation (see list of publications).
• - I did relativistic calculations to calibrate the analyzing magnet from Pelletron for the case of relativistic heavy ion experiments AMS done at the time (see list of publications).

For the Nuclear Astrophysics, at WIS, I accomplished two big activities at the accelerator Van de Graaff of 3 MV:

• - for the p+⁷Be experiment

• o up-grading the existing experimental set-up
• o Participating in the experimental group to fulfill the experiment

• - for the ³He+⁴He experiment

• o gas-target chamber construction, starting with designing and testing it
• o the whole experimental assembly and method testing by running a preliminary experiment for the ³He+⁴He experiment.