# ANKE

### 1. General

The ANKE facility (Apparatus for Studies of Nucleon and Kaon Ejectiles) is a large acceptance forward magnetic spectrometer which was in operation at an internal target station in the COSY ring since 1998. The experimental hadron physics program at ANKE-COSY has been completed at the end of 2014. The data analysis of performed measurements is  ongoing (e.g. by groups from Juelich, Muenster, Dubna, Gatchina, and Tbilisi). The publication record is excellent (see collaboration website). The major experimental results are also part of the review paper "The legacy of the experimental hadron physics program at COSY" published in European Physics Journal A.

### 2. Research program

In 2005 a SPIN program was outlined to exploit the possibilities of carrying out experiments with polarized beams and targets at ANKE (link to SPIN. Since this time many results relevant to a detailed understanding of nuclear and hadronic physics has been achieved, in particular on the following topics (for a full list of proposals see here):

1. double-polarized experiments in Nucleon-Nucleon (pp and pn) sector;
2. double-polarized experiment in close to threshold pion production in pn collisions;
3. double-polarized experiment in strangness production (lambda hyperon).

### 3. Technical developments at ANKE

The collaboration has been successful at developing and implementing new hardware for experiments and the following technologies will be further exploited:

#### (i) Polarized Internal Terget (PIT)

Since 2005 the ANKE spectrometer has been equipped with a Polarized Internal Target. The PIT consists  of: an Atomic Beam Source (ABS), a vacuum target chamber, and a Lamb-Shift Polarimeter (LSP). The polarized Hydrogen and Deuterium gas targets collaboration have been used to measure the spin dependence of many nuclear reactions.

#### (ii) Openable Storage Cell

The operation of the openable (closable) storage cell for polarized gas targets at ANKE has been conducted successfully. The cell functioned in a very stable and reliable way. The desired increase of the luminosity has been achieved, when passing a pre-cooled stacked COSY beam through the cell. The gain factor in density of the (hydrogen/deuterium) gas target of the order of 5 has been demonstrated,  which is close to the expected figure. In a titanium cell a high degree of polarisation for hydrogen (85%) and deuterium (70%) has been obtained.

#### (iii) Silicon Tracking Telescopes (STT)

Very efficient siliilicon tracking telescopes for spectator recoil particles of low energy have been operated at ANKE since the first experiments.

#### (iv) ANKE dipole magnet (D2)

The central dipole magnet of the ANKE spectrometer (with the maximum field of 1.6 T) is a movable system to adjust the momenta of the detected particles independent of the beam momentum. Currently the D2 magnet has been taken out from its internal position in the COSY ring and placed inside the ring hall for the ExB deflector development for the EDM search project.

# Local contact persons in IKP-2:



ANKE spokesperson

Dr. Andro Kacharava



Polarized Internal Target (PIT)

Dr. Ralf Engels



Silicon Tracking Telescopes (STT)

Dr. Ralf Schleichert