One of the greatest problems facing modern physics is the apparent asymmetry between matter and antimatter. While the standard model of particle physics predicts that equal amounts of matter and antimatter were produced following the Big Bang, astronomical observations have revealed that our universe contains little or no primordial antimatter. Precision measurements of cold, trapped antiparticles can be used to probe fundamental symmetries, and may shed light on why antimatter is so scarce in our universe. The ALPHA experiment at the CERN Antiproton Decelerator studies magnetically trapped antihydrogen atoms, produced by slowly merging cold plasmas of positrons (e +) and antiprotons (¯p). The precision spectroscopy of antihydrogen has already provided unique, high-resolution tests of CPT invariance and theories of new physics beyond the standard model. During 2018, the ALPHA experiment was expanded with the addition of ALPHA-g, a vertical atom trap that is intended to make the first direct measurements of antimatter gravitation.
The efficient transport of ¯p and e + plasmas into the ALPHA-g experiment will be essential to trapping large numbers of antihydrogen atoms. However, the transfer of low energy (. 100 eV) charged particles between separate traps with strong magnetic fields is challenging for a variety of reasons. This thesis describes the design and commissioning of charged particle beamlines for the upgraded ALPHA experiment, and the methods that were used to overcome these challenges.
In this thesis, we first describe the development of a novel magnetic beamline for the ALPHA experiment. Semi-analytical and numerical models are used to characterise the dynamics of ¯p and e + bunches within this beamline. Next, we describe the implementation of the ALPHA-g beamlines at CERN during 2018. We review the specifications of the beamline magnets, and describe the control system used to manage their operation. Finally, a range of diagnostic tools are developed to experimentally measure the properties of actual ¯p and e + bunches. We combine data from a range of sources to evaluate the performance of the beamline, and show that large numbers of positrons and antiprotons can already be delivered to the ALPHA-g experiment. In summary, the work presented in this thesis is critical to a future ±1% measurement of antimatter gravitation, as well as continued precision measurements of antihydrogen atoms.
Mark A. Johnson
Mojawapo ya matatizo makubwa yanayokabili fizikia ya kisasa ni kutofanana kwa mambo kati ya vitu na vitu visivyo vya asili. Ingawa mfano wa kawaida wa fizikia ya chembe za chembe za urithi unataja kwamba kiasi sawa cha vitu na vitu vilivyobadilika viliundwa baada ya Big Bang, uchunguzi wa nyota umeonyesha kwamba ulimwengu wetu una vitu vichache au hauna vitu vilivyobadilika. Uchunguzi wa antiparticles za baridi, zilizokamatwa, zinaweza kutumiwa kuchunguza ulinganifu wa msingi, na inaweza kutoa mwangaza juu ya kwa nini antimatter ni nadra sana katika ulimwengu wetu. Majaribio ya ALPHA katika CERN Antiproton Decelerator hujifunza atomu za antihydrogen zilizokamatwa kwa sumaku, zinazozalishwa kwa kuunganisha polepole plasma baridi ya positrons (e +) na antiprotons (p). Spectroscopy ya antihydrogen ya usahihi tayari imetoa vipimo vya kipekee vya azimio la juu la invariance ya CPT na nadharia za fizikia mpya zaidi ya mfano wa kawaida. Katika 2018, jaribio la ALPHA liliongezwa na ALPHA-G, mtego wa atomiki wa wima ambao unakusudiwa kufanya vipimo vya kwanza vya moja kwa moja vya mvuto wa antimatter. Uhamisho mzuri wa p na e + plasma katika jaribio la ALPHA-g utakuwa muhimu kwa kukamata idadi kubwa ya atomu za antihydrogen. Hata hivyo, uhamisho wa nishati ya chini ( "Kutumia ""eV"" ya 100 eV kati ya nyara tofauti na mashamba ya nguvu ya sumaku ni changamoto kwa sababu mbalimbali." Thesis hii inaelezea kubuni na kuagiza beamlines ya chembechembe za malipo kwa majaribio ya ALPHA iliyoboreshwa, na mbinu ambazo zilitumiwa kushinda changamoto hizi. Katika thesis hii, sisi kwanza kuelezea maendeleo ya riwaya magnetic beamline kwa ajili ya jaribio ALPHA. Semi-analytical na tarakimu mifano ni kutumika kwa sifa ya nguvu ya p na e + makundi ndani ya beamline hii. Katika makala hii, tutaelezea jinsi ya kuanzisha ALPHA-G beamlines katika CERN. Sisi kupitia vipimo ya beamline sumaku, na kuelezea mfumo wa kudhibiti kutumika kusimamia operesheni yao. Hatimaye, mbalimbali ya zana za utambuzi ni maendeleo ya majaribio kupima mali ya halisi p na e + makundi. "Kutokana na data kutoka vyanzo mbalimbali, tunaweza kuchunguza utendaji wa beamline na kuonyesha kwamba idadi kubwa ya positrons na antiprotons tayari inaweza kutolewa kwa majaribio ya ""Alpha-G.""" Kwa muhtasari, kazi iliyotolewa katika thesis hii ni muhimu kwa ajili ya baadaye ± 1% kipimo cha antimatter mvuto, kama vile kuendelea vipimo usahihi wa atomu antihydrogen. A. Mark Johnson