1. Low Alpha & CSR in the MLS (PTB) G. Wüstefeld (BESSY) et al, ESLS XVI, Daresbury, Nov 28th. 2008 1 Low Alpha Optics and Coherent Synchrotron Radiation in the MLS J. Feikes, M. v. Hartrott, G. Wüstefeld (BESSY) A. Hoehl, R. Klein, R. Müller, G. Ulm (PTB) BESSY & PTB, Berlin (Germany) PTB = German National Metrology Institute

2. Low Alpha & CSR in the MLS (PTB) G. Wüstefeld (BESSY) et al, ESLS XVI, Daresbury, Nov 28th. 2008 2 content 1. Low alpha optics 2. Coherent Synchrotron Radiation

3. Low Alpha & CSR in the MLS (PTB) G. Wüstefeld (BESSY) et al, ESLS XVI, Daresbury, Nov 28th. 2008 3 The Metrology Light Source (MLS) of the PTB (German National Metrology Institute) 3rd sextupole family octupole family low alpha tuning 3rd sextupole & 1 octupole families E= 100 MeV to 630 MeV 2 R = 48 m 4 cell DBA field 2500T/m length 0.1m

4. Low Alpha & CSR in the MLS (PTB) G. Wüstefeld (BESSY) et al, ESLS XVI, Daresbury, Nov 28th. 2008 4 MLS low alpha optics vers Q1-current 630 MeV@500kV tuning range of low alpha optics 4.4 < fs< 145 kHz 0.0001 < 0.12 low alpha opticsuser optics quad1-current/A user optics

5. Low Alpha & CSR in the MLS (PTB) G. Wüstefeld (BESSY) et al, ESLS XVI, Daresbury, Nov 28th. 2008 5 2 chrom. sextupole fam. 3 chrom. sextupole fam. 1 chrom. octupole fam. low alpha tuning by sextupoles and octupoles keep away from zero! MAD simulation, MLS TDR, 2003

6. Low Alpha & CSR in the MLS (PTB) G. Wüstefeld (BESSY) et al, ESLS XVI, Daresbury, Nov 28th. 2008 6 measured fs-tuning long. chrom corr. octupole excited synchrotron frequency vers rf-detuning synchrotron frequency vers p/p long. chrom corr. octupole excited

7. Low Alpha & CSR in the MLS (PTB) G. Wüstefeld (BESSY) et al, ESLS XVI, Daresbury, Nov 28th. 2008 7 IR beam line at MLS THz beam spot acceptance 64x43 mrad 2 THz detector Si-bolometer rise time ~1 ms frequency 0.1 – 15 THz NEP~10 W/ Hz -13 InSb-detector rise time ~1 s frequency 0.1 – 1.5 THz NEP~10 W/ Hz -12 THz beam line still under construction !

8. Low Alpha & CSR in the MLS (PTB) G. Wüstefeld (BESSY) et al, ESLS XVI, Daresbury, Nov 28th. 2008 8 information from THz signals THz-frequency domain Fourier spectrometer THz-time domain fast detectors

9. Low Alpha & CSR in the MLS (PTB) G. Wüstefeld (BESSY) et al, ESLS XVI, Daresbury, Nov 28th. 2008 9 THz signals at MLS: time domain modulated THz signal FTS (bursting) THz signal THz detector power time frequency FFT THz signals at MLS: frequency domain THz signal THz detector osci power

10. Low Alpha & CSR in the MLS (PTB) G. Wüstefeld (BESSY) et al, ESLS XVI, Daresbury, Nov 28th. 2008 10 THz signals at 3 different settings THz power is manipulated by variation, @ 30 mA beam current

11. Low Alpha & CSR in the MLS (PTB) G. Wüstefeld (BESSY) et al, ESLS XVI, Daresbury, Nov 28th. 2008 11 30 mV & 20 ms 9 mV & 20 ms200 mV & 20 ms appearance of CSR bursting in time domain

12. Low Alpha & CSR in the MLS (PTB) G. Wüstefeld (BESSY) et al, ESLS XVI, Daresbury, Nov 28th. 2008 12 CSR signals in frequency domain-1 50 kV 400 kV bursting threshold 630MeV voltage scan 50 kV to 400 kV, 0.16mA SB, 630 MeV THz-signal frequency 40 kHz 0 kHz 400 kV 50 kV rf-voltage

13. Low Alpha & CSR in the MLS (PTB) G. Wüstefeld (BESSY) et al, ESLS XVI, Daresbury, Nov 28th. 2008 13 60 kV 500 kV 60 kV 500 kV 60 kV 70 kV 110 kV CSR bursting signals in frequency domain-2 630MeV bursting threshold bursting threshold ?? bursting threshold

14. Low Alpha & CSR in the MLS (PTB) G. Wüstefeld (BESSY) et al, ESLS XVI, Daresbury, Nov 28th. 2008 14 Bursting thresholds measured at MLS variation of current, bunch length, voltage, energy BESSY fit coloured dots indi- cate different sets of measurement I ~ 3/8 I ~ 3/7 rms nat. bunch length x 1.7 / mm scaled current ~ I / V f 1/3 rev

15. Low Alpha & CSR in the MLS (PTB) G. Wüstefeld (BESSY) et al, ESLS XVI, Daresbury, Nov 28th. 2008 15 MLS scaling law = zero-current-bunch length V = rf-voltage I = current per bunch = 1.0 mm V = 250 kV I = 0.33 mA 0 0 0 includes many parameters it can be expressed as: =bunch length, =moment. comp. factor, c=speed of light, f = syn.frequency, e=unit charge, V=voltage gradient, 2 R=circumference, E=energy s = [(V I )/(V I 0 0 0 3/7 = c /(2 f ), f = (e c V )/(2 RE) e s s 2 2

16. Low Alpha & CSR in the MLS (PTB) G. Wüstefeld (BESSY) et al, ESLS XVI, Daresbury, Nov 28th. 2008 16 Conclusion: the low alpha optics extends the usage of storage rings to intense THz and short X-ray pulses the low alpha optics works excellent the bursting scales as predicted coherent THz radiation as a diagnostics tool delivers sensitive and new information on beam dynamics