JLab Polarized He3 Target System home page

JLab Polarized He3 Target System

Introduction to the JLab Polarized ³He Target:

Based on the principle of spin exchange between optically pumped Rb-K mixture or pure Rb vapor and ³He gas.
40-cm long (or other length) sealed glass cell containing approximately 10 atm ³He gas.
Maximum Polarization reached > 70%, thickness 10²² atoms/cm².
With 15 uA beam, the luminosity reached 10³⁶particles/cm²/s and in-beam polarization reached ~ 55-60%.
Figure-Of-Merit (FOM) reached A New World Record! .
With no free polarized neutron target available, polarized ³He target provides a target close to a polarized neutron target since the spin of the two protons in ³He are almost all paired in opposite directions.

Status of the Polarized ³He Target Work:

A polarized ³He target was built in 1998 and has been undergoing upgrade and improvement continuously.
A permanent polarized ³He target lab (a laser room and a control room) was built in 1998 in EEL building. The target system was initially built and tested in the lab. Subsequent upgrades, R-and-Ds and numerous tests were performed here.
A 2nd laser building was built in 2005 next to the Hall A counting house to allow setting-up and testing the polarized ³He target for experiment(s). An optical fiber system is used to transport the laser light into the hall.
The target was a critical part for 13 experiments in 6 GeV era.
It is currently going through an upgrade for experiments in 12 GeV era, aiming to increase the FOM by about a factor of 8 in two stages.
If you would like to contribute to the polarized ³He target effort, please contact the polarized ³He target program coordinator J. P. Chen at 269-7413.
You will need laser training before you can work in the target lab. The training includes General Laser Safety Training (contact JLab laser safety officer Bert Manzlak at 269-7556), an eye exam and the system specific training (read the safety documents Laser Safety Operation Procedure (LSOP) and Operation Safety Procedure (OSP), then contact the laser system supervisor J. P. Chen at 269-7413).

Progress and Status of the Polarized ³He Physics Program:

Thirteen experiments using the polarized ³He target have successfully completed data taking from 1998 to 2009.
The last series of experiments, leading by the transversity (E06-010) experiment, had target polarized in vertical as well as tranverse and longitudinal directions. Fast spin reversal every 20 minutes was established. Narrow-width lasers and hybrid (Rb-K mixture) cell helped the transversity experiment to reach a maximum in-beam polarization ~60% with up to 15 uA and fast spin reversal. The average polarization over the experiment was ~55%.
Many papers were published or submitted for publication (listed for each experiment, see Completed Experiments below).
A number of students got their PhDs from the polarized ³He program (listed for each experiment), including J. Huang, MIT, on E06-010, received the APS-GHP thesis award and three (X. Zheng, MIT, on E99-117 in 2002, K. Slifer, Temple, on E94-010 in 2004, and X. Qian, Duke, on E06-010) received JLab/SURA (JLab/JSA) thesis award,
A number of experiments using the polarized ³He target are aprroved to run in 12 GeV era and are key components of the physics program for the JLab 12 GeV upgrade. They require further upgrade of the polarized ³He target to increase FOM by a factor of 3 to 8.

Polarized ³He Target Experiments in Hall A:

Completed Experiments:

E94-010: Measurement of the Neutron (³He) Spin Structure Function at Low Q²; a connection between the Bjorken and GDH sum rules.
E95-001: Transverse Asymmetry A_T from ³He (e,e')at low Q.
E99-117: Aⁿ₁ at Large x using JLab at 6 GeV.
E97-103: Search for Higher Twist Effects in the Neutron Spin Structure Function gⁿ₂.
E01-012: Neutron (³He) spin structure functiuons in the resonance region - spin duality.
E97-110: The GDH Sum Sule and Spin Structure of ³He and the Neutron Using Nearly Real Photons.
E02-013: Neutron Electric Form Factor G_En at High Q².
E06-010: Single Target-Spin Asymmetry in Semi-Inclusive Pion Electroproduction on a Transversely Polarized ³He Target.
E07-013: Normal Target Single-Spin Asymmetry in Inclusive n(e,e') with a Polarized ³He Target.
E06-014: Precision measurements of d_2n: color polarizabilities.
E05-015: Target Single Spin Asymmetry in Quasi-Elastic ³He(e, e') Reaction.
E05-012: A_x and A_z in Quasi-Elastic ³He(e, e'd) Reaction
E08-005: Target Single-Spin Asymmetry Ay in Quasi-Elastic ³He(e,e'n) Reaction

Approved 12 GeV Experiments:

E12-06-122: A1n in the Valance Quark Region Using an 11 GeV Beam and a Polarized ³He target in Hall C
E12-06-122: Neutron g2 and d2 at High Q² in Hall C
E12-06-122: A1n in the Valance Quark Region Using 8.8 GeV and 6.6 GeV Beam Energies and Bigbite Spectrometer in Hall A
E12-09-018: SIDIS Pion and Kaon Electroproduction on a Transversely Polarized ³He Target using the Super BigBite and Bigbite Spectrometers in Hall A
E12-09-016: GEn/GMn at High Q²
E12-09-014:Target Single Spin Asymmetry in SIDIS (e,e'pi) Reaction on a Transversely Polarized ³He Target at 8.8 and 11 GeV
E12-11-007:Asymmetries in SIDIS (e,e'pi) Reactions on a Longitudinally Polarized ³He Target at 8.8 and 11 GeV

Safety Documents:

Collaborations and Related Sites:

Collaborating Institutions: (Duke, JLab, Kentucky, Temple, UVa and William and Mary; earlier, also Caltech and MIT)
Current active members: Supervisor: J. P. Chen, Students: Jie Liu, Jin Kai, Nguyen Ton.
Former students: Alexandre Deur, Pibero Djawothi, Stenphen Jensen, Ioannis Kominis, Karl Slifer; Kevin Kramer; Xiaochao Zheng; Patricia Solvignon; Vince Sulkosky, Jaideep Singh; Aidan Kelleher, Ameya Kolarkar;Chiranjib Dutta, Jin Huang, Yi Zhang; Joe Katich; Yawei Zhang.
Former postdocs:Sebastian Incerti, Meimei Liang, David Pripstein; Xiaofei Zhu; Yi Qiang; Zhiwen Zhao.
Polarized ³He Target Lab at University of Virginia.
Polarized ³He Target Lab at William and Mary.

This page is maintained by J. P. Chen. Last Update: August 31, 2015.
Email: jpchen@jlab.org, Phone: (757)269-7413.