Progress of the Novel Spiral Injec6on Test Experiment

Muhammad Abdul Rehman1, Hiromi Iinuma3, Satoshi Ohsawa1,2, Hisayoshi Nakayama1,2, Kazuro Furukawa1,2
Tsutomu Mibe1,2, Hiromi Hisamatsu2
1The Graduate University for Advanced Studies(SOKENDAI)
2 High Energy Accelerator Research OrganizaEon(KEK)

rehman@post.kek.jp

3InsEtute of Quantum Beam Science of Graduate School of Science and Engineering, Ibaraki University

Abstract

A new muon g – 2 / EDM experiment at J-PARC (E34) is under prepara6on in order to resolve a 3 sigma discrepancy of muon anomalous magne6c dipole moment between the measurement and thestandard model predic6on. The E34 experiment will employ a unique three-dimensional spiral injec6on scheme to store the muon beam into a small storage orbit. In order to demonstrate thefeasibility of novel injec6on scheme, the Spiral Injec6on Test Experiment (SITE) with the electron beam is under construc6on at KEK Tsukuba campus. In order to demonstrate the feasibility of thisnovel injec6on scheme, the Spiral Injec6on Test Experiment (SITE) with the electron beam is under construc6on at KEK Tsukuba campus. The goals of the SITE are divided into two phases. In the ﬁrst
phase of the SITE, 80 keV DC electron beam was injected and detected as a ﬂuorescent light due to the de-excita6on of the nitrogen gas into solenoidal storage magnet. In the second phase of theSITE, the pulsed electron beam, and a pulsed magne6c kicker are developed in order to keep the pulsed beam on the very midplane of the solenoidal storage magnet. This paper describes theachievements of the ﬁrst phase of the SITE and progress towards the second phase.

Muon g – 2 Experiment

The muon's anomalous magne6c moment is one of biggest discrepancies inelementary par6cle physics and extremely sensi6ve to the new physics. The
most recent measurement of muon g - 2 results in 3 σ discrepancy between
measured and standard model predic6on. The J-PARC new muon g – 2 / EDM(E34) experiment is aiming to measure muon g – 2 to the precision of 0.1 ppm
and EDM down to the sensi6vity of 10-21 e.cm.

Three-dimensional Spiral Injec6on Scheme

Conven6onal Injec6on Scheme

New Spiral Injec6on Scheme

Not applicable for small
storage orbit due technicalchallengesØSalient Features

The three-dimensional spiral injec6on scheme isan unproven idea, therefore, a demonstra6on
experiment to prove the feasibility of this uniquescheme is inevitable. A scale down Spiral Injec6on
Test Experiment (SITE) by the use of electron beam
is under development at KEK Tsukuba campus.

4. Pulsed Magne6c Kicker

1. Spiral Injec6on Scheme Test Experiment

The SITE setup contains a 2 m long straight beamline, a solenoid storage magnet tostore the electron beam and forty degrees bend sec6on to guide the electron beam
towards the storage magnet.
Parameters
E34
Storage Magnet
3 [T]
ﬁeld
Injec6on Angle
40(Degree)
Momentum [MeV/300c]
Cyclotron period
7.4[nsec]

SITE
80~100GaussØSmooth connec6on between injec6onand storage sec6onØAll in one storage magnet, which reduce
source of error ﬁelds
ØNo need to kick within a single turn.

A pulsed magne6c kicker is used
to decrease the pitch angle (ψ)
of the beam. Side ﬁgure isillustra6ng the character of themagne6c kicker.
​/↓01*0 =​/↓2340 516(​!!/​7↓01*0 8)

25

4.1 Kicker Coil Design

0.296

Two design of magne6c kicker are under development. In the ﬁrst design
a symmetric (2!) kicker is considered and other possible design is limited
region kicker (!/6).

5.0

Weak Focusing​/↓9 =​/↓( ()−6​∆;/; +6​​9↑! /!​;↑! )
​/↓; =−6​9/; /​ ↓( 

2. Beam Detec6on in the Storage Magnet

4.2 Tracking in Kicker Field

XY-Coupled beam is required

Storage magnet vacuum chamber ﬁlled with the nitrogen gas. Inorder to observe the electron beam as a ﬂuorescent light due
the de excita6on of nitrogen molecules (390 nm < λ < 470 nm). A
chilled CCD-camera is used to observe ﬂuorescence light .

Parameters! !
! /#Pitch angle ψ (rad)95
Both types0of .kicker shapes ( and ) will tested for the SITE.
4.4: Power Supply Design
4.3: Kicker Design
01
8!/#!!

​!/#The !/# kicker coil shape has been op6mized to reduce the inductance ofcoils. The op6miza6on results in the coils of height 175 mm, width 62 mm
and the gap between coils was 35 mm with the inductance of 0.8 µH.

Bkick(G)

3. Electric Chopper
For the second stage of the SITE, development ofpulsed electron beam has been started. Electricchopper has been designed, simulated and fabricatedto produce the pulsed electron beam for the second
stage of the SITE.

​#↓% =​'(()​*↑! )​,↑! /. %CST Simula6on of Chopper

Pulsed beam signal from Faraday CupT(ns)

0.948

0.
07
99595

Conclusion

A new three-dimensional spiral injec6on is under development by using the electron beam in order to realize
new J-PARC's muon g - 2/EDM experiment.
§ The electron beam in the storage magnet was conﬁrmed as ﬂuorescent light due to the de-excita6on ofnitrogen gas in the storage magnet.
§ The required beam phase space for the spiral injec6on has been calculated and implemented.
§ A pulsed magne6c kicker and the power supply is under development to guide the pulsed beam at themidplane of the storage magnet